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'MPLS-TE') ** Downref: Normative reference to an Experimental RFC: RFC 2154 (ref. 'SEC-OSPF') -- Obsolete informational reference (is this intentional?): RFC 2370 (ref. 'OPAQUE') (Obsoleted by RFC 5250) Summary: 7 errors (**), 0 flaws (~~), 11 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Srisuresh 3 INTERNET-DRAFT Caymas Systems, Inc. 4 Expires as of September 3, 2004 P. Joseph 5 Force10 Networks 6 March 3, 2004 8 OSPF-xTE: An experimental extension to OSPF for Traffic Engineering 9 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six 22 months and may be updated, replaced, or obsoleted by other documents 23 at any time. It is inappropriate to use Internet- Drafts as 24 reference material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 Abstract 34 This document defines OSPF-xTE, an experimental traffic engineering 35 (TE) extension to the link-state routing protocol OSPF. OSPF-xTE 36 defines new TE LSAs to disseminate TE metrics within an autonomous 37 System (AS), which may consist of multiple areas. Further, When an 38 AS consists of TE and non-TE nodes, OSPF-xTE ensures that Non-TE 39 nodes in the AS are uneffected by the TE LSAs. OSPF-xTE generates 40 a stand-alone TE Link State Database (TE-LSDB), distinct from the 41 native OSPF LSDB, for computation of TE circuit paths. OSPF-xTE is 42 versatile and extendible to non-packet networks such as SONET/TDM 43 and optical networks. 45 Table of Contents 46 1. Introduction ................................................3 47 2. Principles of traffic engineering ...........................3 48 3. Terminology .................................................4 49 3.1. Native OSPF terms ......................................4 50 3.2. OSPF-xTE terms .........................................5 51 4. Motivations behind the design of OSPF-xTE ...................8 52 4.1. Scalable design ........................................8 53 4.2. Operable in mixed and peer networks ....................9 54 4.3. Efficient in flooding reach ............................9 55 4.4. Ability to reserve TE-exclusive links ..................9 56 4.5. Extendible design .....................................10 57 4.6. Unified for packet and non-packet networks ............10 58 4.7. Networks benefiting from the OSPF-xTE design ..........10 59 5. OSPF-xTE solution overview .................................11 60 5.1. OSPF-xTE Solution .....................................11 61 5.2. Assumptions ...........................................13 62 6. Opaque LSAs to OSPF-xTE transition strategy ................14 63 7. OSPF-xTE router adjacency - TE topology discovery ..........14 64 7.1. The OSPF Options field ................................15 65 7.2. The Hello Protocol ....................................15 66 7.3. Flooding and the Synchronization of Databases .........16 67 7.4. The Designated Router .................................16 68 7.5. The Backup Designated Router ..........................16 69 7.6. The graph of adjacencies ..............................17 70 8. TE LSAs for packet network .................................18 71 8.1. TE-Router LSA (0x81) ..................................19 72 8.2. TE-incremental-link-Update LSA (0x8d) .................28 73 8.3. TE-Circuit-paths LSA (0x8C) ...........................30 74 8.4. TE-Summary LSAs .......................................32 75 8.5. TE-AS-external LSAs (0x85) ............................35 76 9. TE LSAs for non-packet network .............................37 77 9.1. TE-Router LSA (0x81) ..................................37 78 9.2. TE-Positional-ring-network LSA (0x82) .................39 79 9.3. TE-Router-Proxy LSA (0x8e) ............................41 80 10. Abstract topology representation with TE support ...........42 81 11. Changes to Data structures in OSPF-xTE routers .............44 82 11.1. Changes to Router data structure .....................44 83 11.2. Two set of Neighbors .................................44 84 11.3. Changes to Interface data structure ..................44 85 12. IANA Considerations ........................................45 86 12.1. TE LSA type values ...................................45 87 12.2. TE TLV tag values ....................................46 88 13. Acknowledgements ...........................................46 89 14. Security Considerations ....................................47 90 15. Normative References .......................................48 91 16. Informative References .....................................48 93 1. Introduction 95 This document defines OSPF-xTE, an experimental traffic 96 engineering (TE) extension to the link-state routing protocol 97 OSPF. The objective of OSPF-xTE is to discover TE network 98 topology and disseminate TE metrics within an autonomous system 99 (AS). A stand-alone TE Link State Database (TE-LSDB), different 100 from the native OSPF LSDB, is created to facilitate computation 101 of TE circuit paths. Devising algorithms to compute TE circuit 102 paths is not an objective of this document. 104 OSPF-xTE is different from the Opaque-LSA-based design outlined 105 in [OPQLSA-TE]. Section 4 describes the motivations behind the 106 design of OSPF-xTE. Section 6 outlines a transition path for 107 those currently using [OPQLSA-TE] and wish to experiment with 108 OSPF-xTE. 110 Readers interested in TE extensions for the packet networks 111 alone may skip section 9.0. 113 2. Principles of traffic engineering 115 The objective of traffic engineering (TE) is to set up circuit 116 path(s) between a pair of nodes or links and to forward traffic 117 of a certain forwarding equivalency class (FEC) through the 118 circuit path. Only the unicast circuit paths are considered 119 in this section. Multicast variations are outside the scope. 121 A traffic engineered circuit path is uni-directional and may 122 be identified by the tuple of (FEC, TE circuit parameters, 123 Origin Node/Link, Destination node/Link). 125 Forwarding Equivalency Class (FEC) is a grouping of traffic 126 that is forwarded in the same manner by a node. A FEC may be 127 classified based on a number of criteria as follows. 128 a) Traffic arriving on a specific interface, 129 b) Traffic arriving at a certain time of day, 130 c) Traffic meeting a certain packet based classification 131 criteria (ex: based on a match of the fields in the IP 132 and transport headers within a packet), 133 d) Traffic in a certain priority class, 134 e) Traffic arriving on a specific set of TDM (STS) circuits 135 on an interface, 136 f) Traffic arriving on a certain wavelength of an interface 138 Discerning traffic based on the FEC criteria is mandatory for 139 Label Edge Routers (LERs). The intermediate Label Switched Routers 140 (LSRs) are transparent to the traffic content. LSRs are merely 141 responsible for keeping the circuit in-tact for the circuit 142 lifetime. This document will not address defining FEC criteria, 143 or the mapping of a FEC to circuit, or the associated signaling to 144 set up circuits. [MPLS-TE] and [GMPLS-TE] address the FEC criteria. 145 [RSVP-TE] and [CR-LDP] address signaling protocols to set up 146 circuits. 148 This document is concerned with the collection of TE metrics for 149 all the TE enforceable nodes and links within an autonomous system. 150 TE metrics for a node may include the following. 151 a) Ability to perform traffic prioritization, 152 b) Ability to provision bandwidth on interfaces, 153 c) Support for Constrained Shortest Path First (CSPF) 154 algorithms, 155 d) Support for certain TE-Circuit switch type, 156 e) Support for a certain type of automatic protection 157 switching 159 TE metrics for a link may include the following. 160 a) Available bandwidth, 161 b) Reliability of the link, 162 c) Color assigned to the link, 163 d) Cost of bandwidth usage on the link, 164 e) Membership to a Shared Risk Link Group (SRLG) 166 A number of CSPF algorithms may be used to dynamically set up 167 TE circuit paths in a TE network. 169 OSPF-xTE mandates the originating and the terminating entities of 170 a TE circuit path to be identifiable by their IP addresses. 172 3. Terminology 174 Definitions of majority of the terms used in the context of the 175 OSPF protocol may be found in [OSPF-V2]. MPLS and traffic 176 engineering terms may be found in [MPLS-ARCH]. RSVP-TE and 177 CR-LDP signaling specific terms may be found in [RSVP-TE] and 178 [CR-LDP] respectively. 180 The following subsections describe the native OSPF terms and 181 the OSPF-xTE terms used within this document. 183 3.1. Native OSPF terms 185 3.1.1. Native node (Non-TE node) 186 A native or non-TE node is an OSPF router capable of IP packet 187 forwarding and does not take part in a TE network. A native 188 OSPF node forwards IP traffic using the shortest-path 189 forwarding algorithm and does not run the OSPF-xTE extensions. 191 3.1.2. Native link (Non-TE link) 193 A native (or non-TE) link is a network attachment to a TE or 194 non-TE node used for IP packet traversal. 196 3.1.3. Native OSPF network (Non-TE network) 198 A native OSPF network refers to an OSPF network that does not 199 support TE. Non-TE network, native-OSPF network and non-TE 200 topology are used synonymously throughout the document. 202 3.1.4. LSP 204 LSP stands for "Label Switched Path". LSP is a TE circuit path 205 in a packet network. The terms LSP and TE circuit path are 206 used synonymously in the context of packet networks. 208 3.1.5. LSA 210 LSA stands for OSPF "Link State Advertisement". 212 3.1.6. LSDB 214 LSDB stands for "LSA Database". LSDB is a representation of the 215 topology of a network. A native LSDB, constituted of native OSPF 216 LSAs, represents the topology of a native IP network. TE-LSDB, on 217 the other hand, is constituted of TE LSAs and is a representation 218 of the TE network topology. 220 3.2. OSPF-xTE terms 222 3.2.1. TE node 224 TE-Node is a node in the traffic engineered (TE) network. A 225 TE-node has a minimum of one TE-link attached to it. Associated 226 with each TE node is a set of supported TE metrics. A TE node 227 may also participate in a native IP network. 229 In a SONET/TDM or photonic cross-connect network, a TE node is 230 not required to be an OSPF-xTE node. An external OSPF-xTE node 231 may act as proxy for the TE nodes that cannot be routers 232 themselves. 234 3.2.2. TE link 236 TE Link is a network attachment point to a TE-node and is 237 intended for traffic engineering use. Associated with each 238 TE link is a set of supported TE metrics. A TE link may also 239 optionally carry native IP traffic. 241 Of the various links attached to a TE-node, only the links that 242 take part in a traffic engineered network are called the TE 243 links. 245 3.2.3. TE circuit path 247 A TE circuit path is a uni-directional data path, defined by a 248 list of TE nodes connected to each other through TE links. A 249 TE circuit path is also often referred merely as a circuit path 250 or a circuit. 252 For the purposes of OSPF-xTE, the originating and terminating 253 entities of a TE circuit path must be identifiable by their 254 IP addresses. As a general rule, all nodes and links party to a 255 Traffic Engineered network should be uniquely identifiable by an 256 IP address. 258 3.2.4. OSPF-xTE node (OSPF-xTE router) 260 An OSPF-xTE node is a TE node that runs the OSPF routing protocol 261 and the OSPF-xTE extensions described in this document. 263 An autonomous system (AS) may be constituted of a combination of 264 native and OSPF-xTE nodes. 266 3.2.5. TE Control network 268 The IP network used by the OSPF-xTE nodes for OSPF-xTE 269 communication is referred as the TE control network or simply 270 the control network. The control network can be independent of 271 the TE data network. 273 3.2.6. TE network (TE topology) 275 A TE network is a network of connected TE-nodes and TE-links 276 for the purpose of setting up one or more TE circuit paths. 277 The terms TE network, TE data network and TE topology are 278 used synonymously throughout the document. 280 3.2.7. Packet-TE network (Packet network) 281 A packet-TE network is a TE network in which the nodes switch 282 MPLS packets. An MPLS packet is defined in [MPLS-TE] as a 283 packet with an MPLS header, followed by data octets. The 284 intermediary node(s) of a circuit path in a packet-TE network 285 perform MPLS label swapping to emulate the circuit. 287 Unless specified otherwise, the term packet network is used 288 throughout the document to refer a packet-TE network. 290 3.2.8. Non-packet-TE network (Non-packet network) 292 A non-packet-TE network is TE-network in which the nodes 293 switch non-packet entities such as an STS time slot, a Lambda 294 wavelength or simply an interface. 296 SONET/TDM and Fiber cross-connect networks are examples of 297 non-packet-TE networks. Circuit emulation in these networks 298 is accomplished by the switch fabric in the intermediary 299 nodes (based on TDM time slot, fiber interface or Lambda). 301 Unless specified otherwise, the term non-packet network is 302 used throughout the document to refer a non-packet-TE 303 network. 305 3.2.9. Mixed network 307 A mixed network is a network that is constituted of 308 packet-TE and non-TE networks combined. Traffic in the 309 network is strictly datagram oriented - IP datagrams or 310 MPLS packets. Routers in a mixed network may be TE or 311 native nodes. 313 OSPF-xTE is usable within a packet network or a mixed 314 network. 316 3.2.10. Peer network 318 A peer network is a network that is constituted of packet-TE 319 and non-packet-TE networks combined. In a peer network, a TE 320 node could potentially support TE links for the packet as 321 well as non-packet data. 323 OSPF-xTE is usable within a packet network or a non-packet 324 network or a peer network, which is a combination of the two. 326 3.2.11. CSPF 328 CSPF stands for "Constrained Shortest Path First". Given a TE 329 LSDB and a set of constraints that must be satisfied to form a 330 circuit path, there may be several CSPF algorithms to obtain a 331 TE circuit path that meets the criteria. 333 3.2.12. TLV 335 A TLV stands for an object in the form of Tag-Length-Value. All 336 TLVs are assumed to be of the following format, unless specified 337 otherwise. The Tag and length are 16 bits wide each. The length 338 includes the 4 octets required for Tag and Length specification. 339 All TLVs described in this document are padded to 32-bit 340 alignment. Any padding required for alignment will not be a part 341 of the length field, however. TLVs are used to describe traffic 342 engineering characteristics of the TE nodes, TE links and TE circuit 343 paths. 345 0 1 2 3 346 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 347 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 348 | Tag | Length (4 or more) | 349 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 350 | Value .... | 351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 352 | .... | 353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 355 3.2.13. Router-TE TLVs (Router TLVs) 357 TLVs used to describe the TE capabilities of a TE-node. 359 3.2.14. Link-TE TLVs (Link TLVs) 361 TLVs used to describe the TE capabilities of a TE-link. 363 4. Motivations behind the design of OSPF-xTE 365 There are several motivations that led to the design of OSPF-xTE. 366 OSPF-xTE is scalable, efficient and usable across a variety of 367 network topologies. These motivations are explained in detail in 368 the following subsections. The last subsection lists real-world 369 network scenarios that benefit from the OSPF-xTE. 371 4.1. Scalable design 373 OSPF-xTE area level abstraction provides the scaling required 374 for the TE topology in a large autonomous system (AS). 376 An OSPF-xTE area border router will advertise summary LSAs for 377 TE and non-TE topologies independent of each other. Readers 378 may refer to section 10 for a topological view of the AS from 379 the perspective of a OSPF-xTE node in an area. 381 4.2. Operable in mixed and peer networks 383 OSPF-xTE assumes that an AS may be constituted of coexisting 384 TE and non-TE networks. OSPF-xTE dynamically discovers TE 385 topology and the associated TE metrics of the nodes and links 386 that form the TE network. As such, OSPF-xTE generates a 387 stand-alone TE-LSDB that is fully representative of the TE 388 network. Stand-alone TE-LSDB allows for speedy TE computations. 390 In [OPQLSA-TE], the TE-LSDB is derived from the combination of 391 opaque LSAs and native LSDB. Further, the TE-LSDB thus derived has 392 no knowledge of the TE capabilities of the routers in the network. 394 4.3. Efficient in flooding reach 396 OSPF-xTE is able to identify the TE topology in a mixed network 397 and will limit the flooding of TE LSAs to just the TE-nodes. 398 Non-TE nodes are not bombarded with TE LSAs. 400 In a TE network, a subset of the TE metrics may be prone to rapid 401 change, while others remain largely unchanged. Changes in TE 402 metrics must be communicated at the earliest throughout the 403 network to ensure that the TE-LSDB is up-to-date within the 404 network. As a general rule, a TE network is likely to generate 405 significantly more control traffic than a native network. The 406 excess traffic is almost directly proportional to the rate at 407 which TE circuits are set up and torn down within the TE network. 408 The TE database synchronization should occur much quicker compared 409 to the aggregate circuit set up and tear-down rates. OSPF-xTE 410 defines TE-Incremental-Link-update LSA (section 8.2) to advertise 411 just a subset of the metrics that are prone to rapid changes. 413 The more frequent and wider the flooding frequency, the larger 414 the number of retransmissions and acknowledgements. The same 415 information (needed or not) may reach a router through multiple 416 links. Even if the router did not forward the information past 417 the node, it would still have to send acknowledgements across 418 all the various links on which the LSAs tried to converge. 419 It is undesirable to flood non-TE nodes with TE information. 421 4.4. Ability to reserve TE-exclusive links 423 OSPF-xTE draws a clear distinction between TE and non-TE 424 links. A TE link may be configured to permit TE traffic 425 alone, and not permit best-effort IP traffic on the link. 426 This permits TE enforceability on the TE links. 428 When links of a TE-topology do not overlap the links of a 429 native IP network, OSPF-xTE allows for virtual isolation of 430 the two networks. Best-effort IP network and TE network often 431 have different service requirements. Keeping the two networks 432 physically isolated can be expensive. Combining the two 433 networks into a single physically connected network will 434 bring economies of scale, while service enforceability 435 can be maintained individually for each of the TE and non-TE 436 sections of the network. 438 [OPQLSA-TE] does not support the ability to isolate best- 439 effort IP traffic from TE traffic on a link. All links are 440 subject to best-effort IP traffic. An OSPF router could 441 potentially select a TE link to be its least cost link and 442 inundate the link with best-effort IP traffic, thereby 443 rendering the link unusable for TE purposes. 445 4.5. Extendible design 447 OSPF-xTE design is based on the tried and tested OSPF paradigm, 448 and inherits all the benefits of the OSPF, present and future. 449 TE-LSAs are extendible, just as the native OSPF on which 450 OSPF-xTE is founded. 452 4.6. Unified for packet and non-packet networks 454 OSPF-xTE is usable within a packet network or a non-packet 455 network or a combination peer network. 457 Signaling protocols such as RSVP and LDP work the same across 458 packet and non-packet networks. Signaling protocols merely need 459 the TE characteristics of nodes and links so they can signal the 460 nodes to formulate TE circuit paths. In a peer network, the 461 underlying control protocol must be capable of providing a 462 unified LSDB for all TE nodes (nodes with packet-TE links as well 463 as non-packet-TE links) in the network. OSPF-xTE meets this 464 requirement. 466 4.7. Networks benefiting from the OSPF-xTE design 468 Below are examples of some real-world network scenarios that 469 benefit from OSPF-xTE. 471 4.7.1. IP providers transitioning to provide TE services 472 Providers needing to support MPLS based TE in their IP network 473 may choose to transition gradually. Perhaps, add new TE links 474 or convert existing links into TE links within an area first 475 and progressively advance to offer in the entire AS. 477 Not all routers will support TE extensions at the same time 478 during the migration process. Use of TE specific LSAs and their 479 flooding to OSPF-xTE only nodes will allow the vendor to 480 introduce MPLS TE without destabilizing the existing network. 481 The native OSPF-LSDB will remain undisturbed while newer TE 482 links are added to the network. 484 4.7.2. Providers offering Best-effort-IP & TE services 486 Providers choosing to offer both best-effort-IP and TE based 487 packet services simultaneously on the same physically connected 488 network will benefit from the OSPF-xTE design. By maintaining 489 independent LSDBs for each type of service, TE links are not 490 cannibalized in a mixed network. 492 4.7.3. Large TE networks 494 The OSPF-xTE design is advantageous in large TE networks that 495 require the AS to be sub-divided into multiple areas. OSPF-xTE 496 permits inter-area exchange of TE information, which ensures 497 that all nodes in the AS have up-to-date As-wide TE 498 reachability knowledge. This in turn will make TE circuit 499 setup predictable and computationally bounded. 501 4.7.4. Non-packet networks and Peer networks 503 Vendors may also use OSPF-xTE for their non-packet TE networks. 504 OSPF-xTE defines the following functions in support of 505 non-packet TE networks. 506 (a) "Positional-Ring" type network LSA and 507 (b) Router Proxying - allowing a router to advertise on behalf 508 of other nodes (that are not Packet/OSPF capable). 510 5. OSPF-xTE solution overview 512 5.1. OSPF-xTE Solution 514 A new TE flag is introduced within the OSPF options field to 515 enable discovery of TE topology. Section 8.0 describes the 516 semantics of the TE flag. TE LSAs are designed for use by the 517 OSPF-xTE nodes. Section 9.0 describes the TE LSAs in detail. 519 Changes required of the OSPF data structures to support 520 OSPF-xTE are described in section 11.0. A new TE-neighbors data 521 structure will be used to flood TE LSAs along TE-topology. 523 An OSPF-xTE node will have the native LSDB and the TE-LSDB, 524 A native OSPF node will have just the native LSDB. 525 Consider the following OSPF area constituted of OSPF-xTE and 526 native OSPF routers. Nodes RT1, RT2, RT3 and RT6 are OSPF-xTE 527 routers with TE and non-TE link attachments. Nodes RT4 and RT5 528 are native OSPF routers with no TE links. When the LSA database 529 is synchronized, all nodes will share the same native LSDB 530 OSPF-xTE nodes alone will have the additional TE-LSDB. 532 +---+ 533 | |--------------------------------------+ 534 |RT6|\\ | 535 +---+ \\ | 536 || \\ | 537 || \\ | 538 || \\ | 539 || +---+ | 540 || | |----------------+ | 541 || |RT1|\\ | | 542 || +---+ \\ | | 543 || //| \\ | | 544 || // | \\ | | 545 || // | \\ | | 546 +---+ // | \\ +---+ | 547 |RT2|// | \\|RT3|------+ 548 | |----------|----------------| | 549 +---+ | +---+ 550 | | 551 | | 552 | | 553 +---+ +---+ 554 |RT5|--------------|RT4| 555 +---+ +---+ 556 Legend: 557 -- Native(non-TE) network link 558 | Native(non-TE) network link 559 \\ TE network link 560 || TE network link 562 Figure 6: A (TE + native) OSPF network topology 564 5.2. Assumptions 566 OSPF-xTE is an extension to the native OSPF protocol and does not 567 mandate changes to the existing OSPF. OSPF-xTE design makes the 568 following assumptions. 570 1. An OSPF-xTE node will need to establish router adjacency with 571 at least one other OSPF-xTE node in the area in order for the 572 router's TE-database to be synchronized within the area. 573 Failing this, the OSPF router will not be in the TE 574 calculations of other TE routers in the area. 576 It is the responsibility of the network administrator(s) to 577 ensure connectedness of the TE network. Otherwise, there can 578 be disjoint TE topologies within a network. 580 2. OSPF-xTE nodes must advertise the link state of its TE-links. 581 TE-links are not obligated to support native IP traffic. 582 Hence, an OSPF-xTE node cannot be required to synchronize 583 its link-state database with neighbors on all its links. 584 The only requirement is to have the TE LSDB synchronized 585 across all OSPF-xTE nodes in the area. 587 3. A link in a packet network may be designated as a TE-link or 588 a native-IP link or both. For example, a link may be used for 589 both TE and non-TE traffic, so long as the link is 590 under-subscribed in bandwidth for TE traffic - say, 50% of 591 the link capacity is set aside for TE traffic. 593 4. Non-packet TE sub-topologies must have a minimum of one node 594 running OSPF-xTE protocol. For example, a SONET/SDH TDM ring 595 must have a minimum of one Gateway Network Element(GNE) 596 running OSPF-xTE. The OSPF-xTE node will advertise on behalf 597 of all the TE nodes in the ring. 599 6. Opaque LSAs to OSPF-xTE transition strategy 601 Below is a strategy to transition implementations using opaque 602 LSAs ([OPQLSA-TE]) to adapt OSPF-xTE in a gradual fashion. 604 1. Restrict the use of Opaque-LSAs to within an area. 606 2. Use the TE option flag to construct the TE topologies 607 area-wise. By doing this, the TE topology for the AS will 608 be available at area level abstraction. 610 3. Use TE-Summary LSAs and TE-AS-external-LSAs for inter-area 611 Communication. Make use of the TE-topology within an area to 612 summarize the TE networks in the area and advertise the same 613 to all TE-nodes in the backbone. The TE-ABRs on the backbone 614 area will in-turn advertise these summaries within their 615 connected areas. 617 7. OSPF-xTE router adjacency - TE topology discovery 619 OSPF creates adjacencies between neighboring routers for the purpose 620 of exchanging routing information. In the following subsections, we 621 describe modifications to the OSPF options field and the use of 622 Hello protocol to establish TE capability compliance between 623 neighboring routers in an area. The capability is used as the basis 624 to build TE topology. 626 7.1. The OSPF Options field 628 A new TE flag is introduced within the options field to identify TE 629 extensions to the OSPF. This bit will be used to distinguish routers 630 that support OSPF-xTE. The OSPF options field is present in OSPF 631 Hello packets, Database Description packets, and all link state 632 advertisements. The TE bit, however, is a requirement only for the 633 Hello packets. Use of TE-bit is optional in Database Description 634 packets and LSAs. 636 Below is a description of the TE-Bit. Refer [OSPF-V2], [OSPF-NSSA] 637 and [OPAQUE] for a description of the remaining bits in the 638 options field. 640 -------------------------------------- 641 |TE | O | DC | EA | N/P | MC | E | * | 642 -------------------------------------- 643 The OSPF options field - TE support 645 TE-Bit: This bit is set to indicate support for traffic engineering 646 extensions to the OSPF. The Hello protocol which is used for 647 establishing router adjacency will use the TE-bit to 648 establish OSPF-xTE adjacency. Two routers will not become 649 TE-neighbors unless they agree on the state of the TE-bit. 650 TE-compliant OSPF extensions are advertised only to the 651 TE-compliant routers. All other routers may simply ignore 652 the advertisements. 654 There is however a caveat with the above use of the last remaining 655 reserved bit in the options field. OSPF v2 will have no more 656 reserved bits left for future option extensions. If deemed 657 necessary to leave this bit as is, the OPAQUE-9 LSA (local scope) 658 can be used on each interface to communicate the support for 659 OSPF-xTE. For the reminder of the document, we will assume the 660 above defined TE-bit in options filed is permissible. 662 7.2. The Hello Protocol 664 The Hello Protocol is primarily responsible for dynamically 665 establishing and maintaining neighbor adjacencies. In a TE network, 666 it is not required for all links and neighbors to establish 667 adjacency using this protocol. The Hello protocol will use the 668 TE-bit to establish traffic engineering capability between two 669 OSPF routers. 671 For NBMA and broadcast networks, this protocol is responsible for 672 electing the Designated Router and the Backup Designated Router. 674 Routers supporting the TE option shall be given a higher 675 precedence for becoming a designated router over those that do 676 not support TE. 678 7.3. The Designated Router 680 When a router's non-TE link first becomes functional, it checks to 681 see whether there is currently a Designated Router for the network. 682 If there is one, it accepts that Designated Router, regardless of 683 its Router Priority, so long as the current designated router is 684 TE compliant. Otherwise, the router itself becomes Designated 685 Router if it has the highest Router Priority on the network and is 686 TE compliant. 688 OSPF-xTE must be implemented on the most robust routers, as they 689 become likely candidates to take on the role as designated router. 691 7.4. The Backup Designated Router 693 The Backup Designated Router is also elected by the Hello 694 Protocol. Each Hello Packet has a field that specifies the 695 Backup Designated Router for the network. Once again, TE-compliance 696 must be weighed in conjunction with router priority in electing 697 the backup designated router. 699 7.5. Flooding and the Synchronization of Databases 701 In OSPF, adjacent routers within an area are required to 702 synchronize their databases. However, a more concise requirement 703 is that all routers in an area must converge on the same LSDB. 704 However, as stated in item 2 of section 5.2, a basic assertion 705 by OSPF-xTE is that the links used by the OSPF-xTE control 706 network for flooding must not be required to match the links 707 used by the data network for real-time data forwarding. For 708 instance, it should not be required to run the OSPF-xTE messages 709 over a TE-link that is configured not to permit non-TE traffic. 710 However, the control network must be setup such that a minimum 711 of one path exists between any two OSPF or OSPF-xTE routers 712 within the network for flooding purposes. This revised control 713 network connectivity requirement does not jeopardize 714 convergence of LSDB within an area. 716 In a mixed network, where some of the neighbors are TE 717 compliant and others are not, the designated OSPF-xTE router 718 will exchange different sets of LSAs with its neighbors. 719 TE LSAs are exchanged only with the TE neighbors. Native 720 LSAs are exchanged with all neighbors (TE and non-TE alike). 721 Restricting the scope of TE LSA flooding to just the 722 OSPF-xTE nodes will not effect the native nodes that coexist 723 with the OSPF-xTE nodes. 725 The control traffic for a TE network (i.e., TE LSA 726 advertisement) is likely to be higher than that of a native 727 OSPF network. This is because the TE metrics may vary with each 728 TE circuit setup and the corresponding state change must be 729 advertised at the earliest, not exceeding the MinLSInterval 730 of 5 seconds. To minimize advertising repetitive content, 731 OSPF-xTE defines a new TE-incremental-Link-update LSA 732 (section 8.2) that would advertise just the TLVs that changed 733 for a link. 735 A new OSPFIGP-TE multicast address 224.0.0.24 may be used for 736 the exchange of TE compliant database descriptors during 737 database synchronization. 739 7.6. The graph of adjacencies 741 If two routers have multiple networks in common, they may have 742 multiple adjacencies between them. The adjacency may be one of 743 two types - native OSPF adjacency and TE adjacency. OSPF-xTE 744 routers will form both types of adjacency. 746 Two types of adjacency graphs are possible depending on whether 747 a Designated Router is elected for the network. On physical 748 point-to-point networks, Point-to-Multipoint networks and 749 Virtual links, neighboring routers become adjacent whenever they 750 can communicate directly. The adjacency can be one of 751 (a) TE-compliant or (b) native. In contrast, on broadcast and 752 NBMA networks the designated router and the backup designated 753 router may maintain two sets of adjacency. The remaining routers 754 will form either TE-compliant or native adjacency. In the 755 Broadcast network below, routers RT7 and RT3 are chosen as the 756 designated and backup routers respectively. Routers RT3, RT4 757 and RT7 are TE-compliant. RT5 and RT6 are not. So, RT4 will 758 have TE-compliant adjacency with the designated and backup 759 routers. RT5 and RT6 will only have native adjacency with the 760 designated and backup routers. 762 Network Adjacency 764 +---+ +---+ 765 |RT1|------------|RT2| o--------------------o 766 +---+ N1 +---+ RT1 RT2 768 RT7 769 o::::: 770 +---+ +---+ +---+ /| : 771 |RT7| |RT3| |RT4| / | : 772 +---+ +---+ +---+ / | : 773 | | | / | : 774 +-----------------------+ RT5o RT6o oRT4 775 | | N2 * * : 776 +---+ +---+ * * : 777 |RT5| |RT6| * * : 778 +---+ +---+ ** : 779 o::::: 780 RT3 782 Adjacency Legend: 783 ----- Native adjacency (primary) 784 ***** Native adjacency (Backup) 785 ::::: TE-compliant adjacency (primary) 786 ;;;;; TE-compliant adjacency (Backup) 788 Figure 6: The graph of adjacencies with TE-compliant routers. 790 8. TE LSAs for packet network 792 The OSPFv2 protocol, as of now, has a total of 11 LSA types. 793 LSA types 1 through 5 are defined in [OSPF-v2]. LSA types 6, 7 794 and 8 are defined in [MOSPF], [NSSA] and [BGP-OSPF] respectively. 795 LSA types 9 through 11 are defined in [OPAQUE]. 797 Each LSA type has a unique flooding scope. Opaque LSA types 798 9 through 11 are general purpose LSAs, with flooding 799 scope set to link-local, area-local and AS-wide (except stub 800 areas) respectively. 802 In the following subsections, we define new LSAs for traffic 803 engineering (TE) use. The Values for the new TE LSA types are 804 assigned such that the high bit of the LSA-type octet is set 805 to 1. The new TE LSAs are largely modeled after the existing 806 LSAs for content format and have a unique flooding scope. 808 TE-router LSA is defined to advertise TE characteristics of 809 an OSPF-xTE router and all the TE-links attached to the 810 router. TE-incremental-Link-Update LSA is defined to 811 advertise incremental updates to the metrics of a TE link. 812 Flooding scope for both these LSAs is restricted to an area. 814 TE-Summary network and router LSAs are defined to advertise 815 the reachability of area-specific TE networks and Area Border 816 Routers (along with router TE characteristics) to external 817 areas. Flooding Scope of the TE-Summary LSAs is the TE topology 818 in the entire AS less the non-backbone area for which the 819 the advertising router is an ABR. Just as with native OSPF 820 summary LSAs, the TE-summary LSAs do not reveal the topological 821 details of an area to external areas. 823 TE-AS-external LSA and TE-Circuit-Path LSA are defined to 824 advertise AS external network reachability and pre-engineered 825 TE circuits respectively. While flooding scope for both these 826 LSAs can be the entire AS, flooding scope for the 827 pre-engineered TE circuit LSA may optionally be restricted to 828 just the TE topology within an area. 830 8.1. TE-Router LSA (0x81) 832 The TE-router LSA (0x81) is modeled after the router LSA and has the 833 same flooding scope as the router-LSA. However, the scope is 834 restricted to only the OSPF-xTE nodes within the area. The TE-router 835 LSA describes the TE metrics of the router as well as the TE-links 836 attached to the router. Below is the format of the TE-router LSA. 837 Unless specified explicitly otherwise, the fields carry the same 838 meaning as they do in a router LSA. Only the differences are 839 explained below. Router-TE flags, Router-TE TLVs, Link-TE options, 840 and Link-TE TLVs are each described in the following sub-sections. 842 0 1 2 3 843 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 845 | LS age | Options | 0x81 | 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 847 | Link State ID | 848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 849 | Advertising Router | 850 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 851 | LS sequence number | 852 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 853 | LS checksum | length | 854 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 855 | 0 |V|E|B| 0 | Router-TE flags | 856 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 857 | Router-TE flags (contd.) | Router-TE TLVs | 858 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 859 | .... | 860 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 861 | .... | # of TE links | 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 | Link ID | 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 | Link Data | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 867 | Type | 0 | Link-TE flags | 868 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 869 | Link-TE flags (contd.) | Zero or more Link-TE TLVs | 870 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 871 | Link ID | 872 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 873 | Link Data | 874 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 875 | ... | 877 Option 878 In TE-capable router nodes, the TE-bit may be set to 1. 880 8.1.1. Router-TE flags - TE capabilities of the router 882 The following flags are used to describe the TE capabilities of an 883 OSPF-xTE router. The remaining bits of the 32-bit word are reserved 884 for future use. 886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 887 |L|L|P| | | | |L|S|C| 888 |S|E|S| | | | |S|I|S| 889 |R|R|C| | | | |P|G|P| 890 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 891 |<---- Boolean TE flags ------->|<- TE flags pointing to TLVs ->| 893 Bit LSR 894 When set, the router is considered to have LSR capability. 896 Bit LER 897 When set, the router is considered to have LER capability. 898 All MPLS border routers will be required to have the LER 899 capability. When the E bit is also set, that indicates an 900 AS Boundary router with LER capability. When the B bit is 901 also set, that indicates an area border router with LER 902 capability. 904 Bit PSC 905 Indicates the node is Packet Switch Capable. 907 Bit LSP 908 MPLS Label switch TLV TE-NODE-TLV-MPLS-SWITCHING follows. 909 This is applicable only when the PSC flag is set. 911 Bit SIG 912 MPLS Signaling protocol support TLV 913 TE-NODE-TLV-MPLS-SIG-PROTOCOLS follows. 915 BIT CSPF 916 CSPF algorithm support TLV TE-NODE-TLV-CSPF-ALG follows. 918 8.1.2. Router-TE TLVs 920 The following Router-TE TLVs are defined. 922 8.1.2.4. TE-NODE-TLV-MPLS-SWITCHING 924 MPLS switching TLV is applicable only for packet switched nodes. The 925 TLV specifies the MPLS packet switching capabilities of the TE 926 node. 928 0 1 2 3 929 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 931 | Tag = 0x8001 | Length = 6 | 932 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 933 | Label depth | QOS | | 934 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 936 'Label depth' is the depth of label stack the node is capable of 937 processing on its ingress interfaces. An octet is used to represent 938 label depth. A default value of 1 is assumed when the TLV is not 939 listed. Label depth is relevant when an LER has to pop off multiple 940 labels off the MPLS stack. 942 'QOS' is a single octet field that may be assigned '1' or '0'. Nodes 943 supporting QOS are able to interpret the EXP bits in the MPLS header 944 to prioritize multiple classes of traffic through the same LSP. 946 8.1.2.2. TE-NODE-TLV-MPLS-SIG-PROTOCOLS 948 MPLS signaling protocols TLV lists all the signaling protocol 949 supported by the node. An octet is used to list each signaling 950 protocol supported. 952 0 1 2 3 953 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 954 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 955 | Tag = 0x8002 | Length = 5, 6 or 7 | 956 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 957 | Protocol-1 | ... | .... | 958 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 960 RSVP-TE protocol is represented as 1, CR-LDP as 2 and LDP as 3. 961 These are the only permitted signaling protocols at this time. 963 8.1.2.3. TE-NODE-TLV-CSPF-ALGORITHMS 965 The CSPF algorithms TLV lists all the CSPF algorithm codes 966 supported. Support for CSPF algorithms makes the node eligible to 967 compute complete or partial circuit paths. Support for CSPF 968 algorithms can also be beneficial in knowing whether or not a node 969 is capable of expanding loose routes (in an MPLS signaling request) 970 into a detailed circuit path. 972 Two octets are used to list each CSPF algorithm code. The algorithm 973 codes may be vendor defined and unique within an Autonomous System. 974 If the node supports 'n' CSPF algorithms, the Length would be 975 (4 + 4 * ((n+1)/2)) octets. 977 0 1 2 3 978 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 979 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 980 | Tag = 0x8003 | Length = 4(1 + (n+1)/2) | 981 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 982 | CSPF-1 | .... | 983 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 984 | CSPF-n | | 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 987 8.1.2.4. TE-NODE-TLV-NULL 989 When a TE-Router or a TE-link has multiple TLVs to describe the 990 metrics, the NULL TLV is used to terminate the TLV list. 992 0 1 2 3 993 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 994 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 995 | Tag = 0x8888 | Length = 4 | 996 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 998 8.1.3. Link-TE flags - TE capabilities of a link 1000 The following flags are used to describe the TE capabilities of a 1001 link. The remaining bits of the 32-bit word are reserved for 1002 future use. 1004 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1005 |T|N|P| | | |D| |S|L|B|C| 1006 |E|T|K| | | |B| |R|U|W|O| 1007 | |E|T| | | |S| |L|G| |L| 1008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1009 |<---- Boolean TE flags ------->|<- TE flags pointing to TLVs ->| 1011 TE - Indicates whether TE is permitted on the link. A link 1012 can be denied for TE use by setting the flag to 0. 1014 NTE - Indicates whether non-TE traffic is permitted on the 1015 TE link. This flag is relevant only when the TE 1016 flag is set. 1018 PKT - Indicates whether or not the link is capable of IP 1019 packet processing. 1021 DBS - Indicates whether or not Database synchronization 1022 is permitted on this link. 1024 SRLG Bit - Shared Risk Link Group TLV TE-LINK-TLV-SRLG follows. 1026 LUG bit - Link usage cost metric TLV TE-LINK-TLV-LUG follows. 1028 BW bit - One or more Link bandwidth TLVs follow 1030 COL bit - Link Color TLV TE-LINK-TLV-COLOR follows. 1032 8.1.4. Link-TE TLVs 1034 8.1.4.1. TE-LINK-TLV-SRLG 1036 The SRLG describes the list of Shared Risk Link Groups (SRLG) the 1037 link belongs to. Two octets are used to list each SRLG. If the link 1038 belongs to 'n' SRLGs, the Length would be (4 + 4 * ((n+1)/2)) octets. 1040 0 1 2 3 1041 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1042 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1043 | Tag = 0x0001 | Length = 4(1 + (n+1)/2) | 1044 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1045 | SRLG-1 | .... | 1046 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1047 | SRLG-n | | 1048 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1050 8.1.4.2. TE-LINK-TLV-BANDWIDTH-MAX 1052 The bandwidth TLV specifies maximum bandwidth of the link as follows. 1054 0 1 2 3 1055 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1057 | Tag = 0x0002 | Length = 8 | 1058 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1059 | Maximum Bandwidth | 1060 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1062 Bandwidth is expressed in units of 32 bytes/sec (256 bits/sec). 1063 A 32-bit field for bandwidth would permit specification not exceeding 1064 1 tera-bits/sec. 1066 'Maximum bandwidth' is be the maximum link capacity expressed in 1067 bandwidth units. Portions or all of this bandwidth may be used for 1068 TE use. 1070 8.1.4.3. TE-LINK-TLV-BANDWIDTH-MAX-FOR-TE 1072 The bandwidth TLV specifies maximum bandwidth available for TE use 1073 as follows. 1075 0 1 2 3 1076 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1077 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1078 | Tag = 0x0003 | Length = 8 | 1079 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1080 | Maximum Bandwidth available for TE use | 1081 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1083 Bandwidth is expressed in units of 32 bytes/sec (256 bits/sec). 1084 A 32-bit field for bandwidth would permit specification not exceeding 1085 1 tera-bits/sec. 1087 'Maximum bandwidth available for TE use' is the total reservable 1088 bandwidth on the link for use by all the TE circuit paths traversing 1089 the link. The link is oversubscribed when this field is more than 1090 the 'Maximum Bandwidth'. When the field is less than the 1091 'Maximum Bandwidth', the remaining bandwidth on the link may 1092 be used for non-TE traffic in a mixed network. 1094 8.1.4.4. TE-LINK-TLV-BANDWIDTH-TE 1096 The bandwidth TLV specifies the bandwidth reserved for TE as follows. 1098 0 1 2 3 1099 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1100 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1101 | Tag = 0x0004 | Length = 8 | 1102 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1103 | TE Bandwidth subscribed | 1104 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1106 Bandwidth is expressed in units of 32 bytes/sec (256 bits/sec). 1107 A 32-bit field for bandwidth would permit specification not exceeding 1108 1 tera-bits/sec. 1110 'TE Bandwidth subscribed' is the bandwidth that is currently 1111 subscribed from of the link. 'TE Bandwidth subscribed' must be less 1112 than the 'Maximum bandwidth available for TE use'. New TE circuit 1113 paths are able to claim no more than the difference between the 1114 two bandwidths for reservation. 1116 8.1.4.5. TE-LINK-TLV-LUG 1118 The link usage cost TLV specifies Bandwidth unit usage cost, 1119 TE circuit set-up cost, and any time constraints for setup and 1120 teardown of TE circuits on the link. 1122 0 1 2 3 1123 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1125 | Tag = 0x0005 | Length = 28 | 1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1127 | Bandwidth unit usage cost | 1128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1129 | TE circuit set-up cost | 1130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1131 | TE circuit set-up time constraint | 1132 | | 1133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1134 | TE circuit tear-down time constraint | 1135 | | 1136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1138 Circuit Setup time constraint 1139 This 64-bit number specifies the time at or after which a 1140 TE-circuit path may be set up on the link. The set-up time 1141 constraint is specified as the number of seconds from the start 1142 of January 1, 1970 UTC. A reserved value of 0 implies no circuit 1143 setup time constraint. 1145 Circuit Teardown time constraint 1146 This 64-bit number specifies the time at or before which all 1147 TE-circuit paths using the link must be torn down. The teardown 1148 time constraint is specified as the number of seconds from the 1149 start of January 1 1970 UTC. A reserved value of 0 implies no 1150 circuit teardown time constraint. 1152 8.1.4.6. TE-LINK-TLV-COLOR 1154 The color TLV is similar to the SRLG TLV, in that an Autonomous 1155 System may choose to issue colors to a TE-link meeting certain 1156 criteria. The color TLV can be used to specify one or more colors 1157 assigned to the link as follows. Two octets are used to list each 1158 color. If the link belongs to 'n' number of colors, the Length 1159 would be (4 + 4 * ((n+1)/2)) octets. 1161 0 1 2 3 1162 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1164 | Tag = 0x0006 | Length = 4(1 + (n+1)/2) | 1165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1166 | Color-1 | .... | 1167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1168 | Color-n | | 1169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1171 8.1.4.7. TE-LINK-TLV-NULL 1173 When a TE-link has multiple TLVs to describe its metrics, the NULL 1174 TLV is used to terminate the TLV list. The TE-LINK-TLV-NULL is same 1175 as the TE-NODE-TLV-NULL described in section 8.1.2.4 1177 8.2. TE-incremental-link-Update LSA (0x8d) 1179 A significant difference between a native OSPF network and a TE 1180 network is that the latter may be subject to frequent real-time 1181 circuit pinning and is likely to undergo TE-state updates. Some 1182 links might undergo changes more frequently than others. Flooding 1183 the network with TE-router LSAs at the aggregated speed of all 1184 link metric changes is simply not desirable. A smaller in size, 1185 TE-incremental-link-update LSA is designed to advertise only the 1186 incremental link updates. 1188 TE-incremental-link-Update LSA will be advertised as frequently 1189 as the link state is changed (not exceeding once every 1190 MinLSInterval seconds). The TE-link sequence is largely the 1191 advertisement of a sub-portion of router LSA. The sequence number on 1192 this will be incremented with the TE-router LSA's sequence as the 1193 basis. When an updated TE-router LSA is advertised within 30 minutes 1194 of the previous advertisement, the updated TE-router LSA will assume 1195 a sequence no. that is larger than the most frequently updated of 1196 its links. 1198 Below is the format of the TE-incremental-link-update LSA. 1200 0 1 2 3 1201 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1203 | LS age | Options | 0x8d | 1204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1205 | Link State ID (same as Link ID) | 1206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1207 | Advertising Router | 1208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1209 | LS sequence number | 1210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1211 | LS checksum | length | 1212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1213 | Link Data | 1214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1215 | Type | 0 | Link-TE options | 1216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1217 | Link-TE options | Zero or more Link-TE TLVs | 1218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1219 | # TOS | metric | 1220 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1221 | ... | 1222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1223 | TOS | 0 | TOS metric | 1224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1226 Link State ID 1227 This would be exactly the same as would have been specified as 1228 as Link ID for a link within the router-LSA. 1230 Link Data 1231 This specifies the router ID the link belongs to. In majority of 1232 cases, this would be same as the advertising router. This choice 1233 for Link Data is primarily to facilitate proxy advertisement for 1234 incremental link updates. 1236 Say, a router-proxy-LSA was used to advertise the TE-router-LSA 1237 of a SONET/TDM node. Say, the proxy router is now required to 1238 advertise incremental-link-update for the same SONET/TDM node. 1239 Specifying the actual router-ID the link in the 1240 incremental-link-update-LSA belongs to helps receiving nodes in 1241 finding the exact match for the LSA in their database. 1243 The tuple of (LS Type, LSA ID, Advertising router) uniquely identify 1244 the LSA and replace LSAs of the same tuple with an older sequence 1245 number. However, there is an exception to this rule in the context 1246 of TE-link-update LSA. TE-Link update LSA will initially assume the 1247 sequence number of the TE-router LSA it belongs to. Further, when a 1248 new TE-router LSA update with a larger sequence number is advertised, 1249 the newer sequence number is assumed by al the link LSAs. 1251 8.3. TE-Circuit-path LSA (0x8C) 1253 TE-Circuit-path LSA may be used to advertise the availability of 1254 pre-engineered TE circuit path(s) originating from any router 1255 in the network. The flooding scope may be Area wide or AS wide. 1257 0 1 2 3 1258 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 | LS age | Options | 0x84 | 1261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1262 | Link State ID | 1263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1264 | Advertising Router | 1265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1266 | LS sequence number | 1267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1268 | LS checksum | length | 1269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1270 | 0 |G|E|B|D|S|T|CktType| Circuit Duration (Optional) | 1271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1272 | Circuit Duration cont... | 1273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1274 | Circuit Duration cont.. | Circuit Setup time (Optional) | 1275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1276 | Circuit Setup time cont... | 1277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1278 | Circuit Setup time cont.. |Circuit Teardown time(Optional)| 1279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1280 | Circuit Teardown time cont... | 1281 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1282 | Circuit Teardown time cont.. | No. of TE circuit paths | 1283 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1284 | Circuit-TE ID | 1285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1286 | Circuit-TE Data | 1287 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1288 | Type | 0 | Circuit-TE flags | 1289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1290 | Circuit-TE flags (contd.) | Zero or more Circuit-TE TLVs | 1291 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1292 | Circuit-TE ID | 1293 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1294 | Circuit-TE Data | 1295 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1296 | ... | 1298 Link State ID 1299 The ID of the far-end router or the far-end Link-ID to which the 1300 TE circuit path(s) is being advertised. 1302 TE-circuit-path(s) flags 1304 Bit G - When set, the flooding scope is set to be AS wide. 1305 Otherwise, the flooding scope is set to be area wide. 1307 Bit E - When set, the advertised Link-State ID is an AS boundary 1308 router (E is for external). The advertising router and 1309 the Link State ID belong to the same area. 1311 Bit B - When set, the advertised Link state ID is an Area border 1312 router (B is for Border) 1314 Bit D - When set, this indicates that the duration of circuit 1315 path validity follows. 1317 Bit S - When set, this indicates that Setup-time of the circuit 1318 path follows. 1320 Bit T - When set, this indicates that teardown-time of the 1321 circuit path follows. 1323 CktType 1324 This 4-bit field specifies the Circuit type of the Forward 1325 Equivalency Class (FC). 1327 0x01 - Origin is Router, Destination is Router. 1328 0x02 - Origin is Link, Destination is Link. 1329 0x04 - Origin is Router, Destination is Link. 1330 0x08 - Origin is Link, Destination is Router. 1332 Circuit Duration (Optional) 1333 This 64-bit number specifies the seconds from the time of the 1334 LSA advertisement for which the pre-engineered circuit path 1335 will be valid. This field is specified only when the D-bit is 1336 set in the TE-circuit-path flags. 1338 Circuit Setup time (Optional) 1339 This 64-bit number specifies the time at which the TE-circuit 1340 path may be set up. This field is specified only when the 1341 S-bit is set in the TE-circuit-path flags. The set-up time is 1342 specified as the number of seconds from the start of January 1343 1 1970 UTC. 1345 Circuit Teardown time (Optional) 1346 This 64-bit number specifies the time at which the TE-circuit 1347 path may be torn down. This field is specified only when the 1348 T-bit is set in the TE-circuit-path flags. The teardown time 1349 is specified as the number of seconds from the start of 1350 January 1 1970 UTC. 1352 No. of TE Circuit paths 1353 This specifies the number of pre-engineered TE circuit paths 1354 between the advertising router and the router specified in the 1355 link state ID. 1357 Circuit-TE ID 1358 This is the ID of the far-end router for a given TE-circuit 1359 path segment. 1361 Circuit-TE Data 1362 This is the virtual link identifier on the near-end router for 1363 a given TE-circuit path segment. This can be a private 1364 interface or handle the near-end router uses to identify the 1365 virtual link. 1367 The sequence of (circuit-TE ID, Circuit-TE Data) list the 1368 end-point nodes and links in the LSA as a series. 1370 Circuit-TE flags 1371 This lists the Zero or more TE-link TLVs that all member 1372 elements of the LSP meet. 1374 8.4. TE-Summary LSAs 1376 TE-Summary-LSAs are the Type 0x83 and 0x84 LSAs. These LSAs are 1377 originated by area border routers. TE-Summary-network-LSA (0x83) 1378 describes the reachability of TE networks in a non-backbone 1379 area, advertised by the Area Border Router. Type 0x84 1380 summary-LSA describes the reachability of Area Border Routers 1381 and AS border routers and their TE capabilities. 1383 One of the benefits of having multiple areas within an AS is 1384 that frequent TE advertisements within the area do not impact 1385 outside the area. Only the TE abstractions befitting the 1386 external areas are advertised. 1388 8.4.1. TE-Summary Network LSA (0x83) 1390 TE-summary network LSA may be used to advertise reachability of 1391 TE-networks accessible to areas external to the originating 1392 area. The content and the flooding scope of a TE-Summary LSA 1393 is different from that of a native summary LSA. 1395 The scope of flooding for a TE-summary network is AS wide, with 1396 the exception of the originating area and the stub areas. The 1397 area border router for each non-backbone area is responsible 1398 for advertising the reachability of backbone networks into the 1399 area. 1401 Unlike a native-summary network LSA, TE-summary network LSA does 1402 not advertise summary costs to reach networks within an area. 1403 This is because TE parameters are not necessarily additive or 1404 comparative. The parameters can be varied in their expression. 1405 For example, a TE-summary network LSA will not summarize a 1406 network whose links do not fall under an SRLG (Shared-Risk Link 1407 Group). This way, the TE-summary LSA merely advertises the 1408 reachability of TE networks within an area. The specific circuit 1409 paths can be computed by the BDRs. Pre-engineered circuit paths 1410 are advertised using TE-Circuit-path LSA (refer section 8.3). 1412 0 1 2 3 1413 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1415 | LS age | Options | 0x83 | 1416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1417 | Link State ID (IP Network Number) | 1418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1419 | Advertising Router (Area Border Router) | 1420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1421 | LS sequence number | 1422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1423 | LS checksum | length | 1424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1425 | Network Mask | 1426 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1427 | Area-ID | 1428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1430 8.4.2. TE-Summary router LSA (0x84) 1432 TE-summary router LSA may be used to advertise the availability of 1433 Area Border Routers (ABRs) and AS Border Routers (ASBRs) that are 1434 TE capable. The TE-summary router LSAs are originated by the Area 1435 Border Routers. The scope of flooding for the TE-summary router LSA 1436 is the non-backbone area the advertising ABR belongs to. 1438 0 1 2 3 1439 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1441 | LS age | Options | 0x84 | 1442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1443 | Link State ID | 1444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1445 | Advertising Router (ABR) | 1446 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1447 | LS sequence number | 1448 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1449 | LS checksum | length | 1450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1451 | 0 |E|B| 0 | No. of Areas | 1452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1453 | Area-ID | 1454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1455 | ... | 1456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1457 | Router-TE flags | 1458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1459 | Router-TE TLVs | 1460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1461 | .... | 1462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1464 Link State ID 1465 The ID of the Area border router or the AS border router whose 1466 TE capability is being advertised. 1468 Advertising Router 1469 The ABR that advertises its TE capabilities (and the OSPF areas 1470 it belongs to) or the TE capabilities of an ASBR within one of 1471 the areas the ABR is a border router of. 1473 No. of Areas 1474 Specifies the number of OSPF areas the link state ID belongs to. 1476 Area-ID 1477 Specifies the OSPF area(s) the link state ID belongs to. When 1478 the link state ID is same as the advertising router ID, the 1479 Area-ID lists all the areas the ABR belongs to. In the case 1480 the link state ID is an ASBR, the Area-ID simply lists the 1481 area the ASBR belongs to. The advertising router is assumed to 1482 be the ABR from the same area the ASBR is located in. 1484 Summary-router-TE flags 1486 Bit E - When set, the advertised Link-State ID is an AS boundary 1487 router (E is for external). The advertising router and 1488 the Link State ID belong to the same area. 1490 Bit B - When set, the advertised Link state ID is an Area 1491 border router (B is for Border) 1493 Router-TE flags, 1494 Router-TE TLVs (TE capabilities of the link-state-ID router) 1496 TE Flags and TE TLVs are as applicable to the ABR/ASBR 1497 specified in the link state ID. The semantics is same as 1498 specified in the Router-TE LSA. 1500 8.5. TE-AS-external LSAs (0x85) 1502 TE-AS-external-LSAs are the Type 0x85 LSAs. This is modeled after 1503 AS-external LSA format and flooding scope. TE-AS-external LSAs are 1504 originated by AS boundary routers with TE extensions, and describe 1505 the TE networks and pre-engineered circuit paths external to the 1506 AS. As with AS-external LSA, the flooding scope of the 1507 TE-AS-external LSA is AS wide, with the exception of stub areas. 1509 0 1 2 3 1510 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1511 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1512 | LS age | Options | 0x85 | 1513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1514 | Link State ID | 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 | Advertising Router | 1517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1518 | LS sequence number | 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | LS checksum | length | 1521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1522 | Network Mask | 1523 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1524 | Forwarding address | 1525 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1526 | External Route Tag | 1527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1528 | # of Virtual TE links | 0 | 1529 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1530 | Link-TE flags | 1531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1532 | Link-TE TLVs | 1533 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1534 | ... | 1535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1536 | TE-Forwarding address | 1537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1538 | External Route TE Tag | 1539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1540 | ... | 1542 Network Mask 1543 The IP address mask for the advertised TE destination. For 1544 example, this can be used to specify access to a specific 1545 TE-node or TE-link with an mask of 0xffffffff. This can also 1546 be used to specify access to an aggregated set of destinations 1547 using a different mask. ex: 0xff000000. 1549 Link-TE flags, 1550 Link-TE TLVs 1551 The TE attributes of this route. These fields are optional and 1552 are provided only when one or more pre-engineered circuits can 1553 be specified with the advertisement. Without these fields, 1554 the LSA will simply state TE reachability info. 1556 Forwarding address 1557 Data traffic for the advertised destination will be forwarded to 1558 this address. If the Forwarding address is set to 0.0.0.0, data 1559 traffic will be forwarded instead to the LSA's originator (i.e., 1560 the responsible AS boundary router). 1562 External Route Tag 1563 A 32-bit field attached to each external route. This is not 1564 used by the OSPF protocol itself. It may be used to communicate 1565 information between AS boundary routers; the precise nature of 1566 such information is outside the scope of this specification. 1568 9. TE LSAs for non-packet network 1570 A non-packet network would use the TE LSAs described in the 1571 previous section for a packet network with some variations. 1572 These variations are described in the following subsections. 1574 Two new LSAs, TE-Positional-ring-network LSA and TE-Router-Proxy 1575 LSA are defined for use in non-packet TE networks. 1577 Readers may refer to [SONET-SDH] for a detailed description of 1578 the terms used in the context of SONET/SDH TDM networks, 1580 9.1. TE-Router LSA (0x81) 1582 The following fields are used to describe each router link (i.e., 1583 interface). Each router link is typed (see the below Type field). 1584 The Type field indicates the kind of link being described. 1586 Type 1587 A new link type "Positional-Ring Type" (value 5) is defined. 1588 This is essentially a connection to a TDM-Ring. TDM ring network 1589 is different from LAN/NBMA transit network in that nodes on the 1590 TDM ring do not necessarily have a terminating path between 1591 themselves. Secondly, the order of links is important in 1592 determining the circuit path. Third, the protection switching 1593 and the number of fibers from a node going into a ring are 1594 determined by the ring characteristics. I.e., 2-fiber vs 1595 4-fiber ring and UPSR vs BLSR protected ring. 1597 Type Description 1598 __________________________________________________ 1599 1 Point-to-point connection to another router 1600 2 Connection to a transit network 1601 3 Connection to a stub network 1602 4 Virtual link 1603 5 Positional-Ring Type. 1605 Link ID 1606 Identifies the object that this router link connects to. 1607 Value depends on the link's Type. For a positional-ring type, 1608 the Link ID shall be IP Network/Subnet number just as the case 1609 with a broadcast transit network. The following table 1610 summarizes the updated Link ID values. 1612 Type Link ID 1613 ______________________________________ 1614 1 Neighboring router's Router ID 1615 2 IP address of Designated Router 1616 3 IP network/subnet number 1617 4 Neighboring router's Router ID 1618 5 IP network/subnet number 1620 Link Data 1621 This depends on the link's Type field. For type-5 links, this 1622 specifies the router interface's IP address. 1624 9.1.1. Router-TE flags - TE capabilities of the router 1626 Flags specific to non-packet TE-nodes are described below. 1628 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1629 |L|L|P|T|L|F| |S|S|S|C| 1630 |S|E|S|D|S|S| |T|E|I|S| 1631 |R|R|C|M|C|C| |A|L|G|P| 1632 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1633 |<---- Boolean TE flags ------->|<- TE flags pointing to TLVs ->| 1635 Bit TDM 1636 Indicates the node is TDM circuit switch capable. 1638 Bit LSC 1639 Indicates the node is Lambda switch Capable. 1641 Bit FSC 1642 Indicates the node is Fiber (can also be a non-fiber link 1643 type) switch capable. 1645 9.1.2. Link-TE options - TE capabilities of a TE-link 1647 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1648 |T|N|P|T|L|F|D| |S|L|B|C| 1649 |E|T|K|D|S|S|B| |R|U|W|O| 1650 | |E|T|M|C|C|S| |L|G|A|L| 1651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1652 |<---- Boolean TE flags ------->|<- TE flags pointing to TLVs ->| 1653 TDM, LSC, FSC bits 1654 - Same as defined for router TE options. 1656 9.2. TE-Positional-ring-network LSA (0x82) 1658 Network LSA is adequate for packet TE networks. A new 1659 TE-Positional-Ring-network-LSA is defined to represent type-5 1660 link networks, found in non-packet networks such as SONET/SDH 1661 TDM rings. A type-5 ring is a collection of network elements 1662 (NEs) forming a closed loop. Each NE is connected to two 1663 adjacent NEs via a duplex connection to provide redundancy 1664 in the ring. The sequence in which the NEs are placed on the 1665 Ring is pertinent. The NE that provides the OSPF-xTE 1666 functionality is termed the Gateway Network Element (GNE). 1667 The GNE selection criteria is outside the scope of this 1668 document. The GNE is also termed the Designated Router for 1669 the ring. 1671 The TE-Positional-ring-network LSA (0x82) is modeled after the 1672 network LSA and has the same flooding scope as the network-LSA 1673 amongst the OSPF-xTE nodes within the area. Below is the format 1674 of the TE-Positional-ring-network LSA. Unless specified 1675 explicitly otherwise, the fields carry the same meaning as they 1676 do in a network LSA. Only the differences are explained below. 1677 TE-Positional-ring-network-LSA is originated for each 1678 Positional-Ring type network in the area. The tuple of (Link 1679 State ID, Network Mask) below uniquely represents a ring. The 1680 TE option must be set in the Options flag while propagating 1681 the LSA. 1683 0 1 2 3 1684 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1686 | LS age | Options | 0x82 | 1687 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1688 | Link State ID | 1689 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1690 | Advertising Router | 1691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1692 | LS sequence number | 1693 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1694 | LS checksum | length | 1695 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1696 | Network Mask | 1697 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1698 | Ring Type | Capacity Unit | Reserved | 1699 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1700 | Ring capacity | 1701 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1702 | Network Element Node Id | 1703 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1704 | ... | 1706 Link State ID 1707 This is the IP interface address of the network's Gateway 1708 Network Element, which is also the designated router. 1710 Advertising Router 1711 Router ID of the network's Designated Router. 1713 Ring type 1715 There are 8 types of SONET/SDH rings defined as follows. 1717 1 - A Unidirectional Line Switched 2-fiber ring (2-fiber ULSR) 1718 2 - A bi-directional Line switched 2-fiber ring (2-fiber BLSR) 1719 3 - A Unidirectional Path Switched 2-fiber ring (2-fiber UPSR) 1720 4 - A bi-directional Path switched 2-fiber ring (2-fiber BPSR) 1721 5 - A Unidirectional Line Switched 4-fiber ring (4-fiber ULSR) 1722 6 - A bi-directional Line switched 4-fiber ring (4-fiber BLSR) 1723 7 - A Unidirectional Path Switched 4-fiber ring (4-fiber UPSR) 1724 8 - A bi-directional Path switched 4-fiber ring (4-fiber BPSR) 1726 Capacity unit 1727 Two units are defined at this time as follows. 1728 1 - Synchronous Transport Signal (STS), which is the basic 1729 signal rate for SONET signals. The rate of an STS signal 1730 is 51.84 Mbps 1731 2 - Synchronous Transport Multiplexer(STM), which is the 1732 basic signal rate for SDH signals. The rate of an STM 1733 signal is 155.52 Mbps 1735 Ring capacity 1736 Ring capacity expressed in number of Capacity units. 1738 Network Element Node Id 1740 The Router ID of each of the routers in the positional-ring 1741 network. The list must start with the designated router as 1742 the first element. The Network Elements (NEs) must be listed 1743 in strict clockwise order as they appear on the ring, 1744 starting with the Gateway Network Element (GNE). The number 1745 of NEs in the ring can be deduced from the LSA header's 1746 length field. 1748 9.3. TE-Router-Proxy LSA (0x8e) 1750 This is a variation to the TE-router LSA in that the TE-router LSA 1751 is not advertised by the network element, but rather by a trusted 1752 TE-router Proxy. This is typically the scenario in a non-packet 1753 TE network, where some of the nodes do not have OSPF functionality 1754 and count on a helper node to do the advertisement for them. One 1755 such example would be the SONET/SDH ADM nodes in a TDM ring. The 1756 nodes may principally depend upon the GNE (Gateway Network 1757 Element) to do the advertisement for them. TE-router-Proxy LSA 1758 shall not be used to advertise Area Border Routers and/or AS border 1759 Routers. 1761 0 1 2 3 1762 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1764 | LS age | Options | 0x8e | 1765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1766 | Link State ID (Router ID of the TE Network Element) | 1767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1768 | Advertising Router | 1769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1770 | LS sequence number | 1771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1772 | LS checksum | length | 1773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1774 | 0 | Router-TE flags | 1775 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1776 | Router-TE flags (contd.) | Router-TE TLVs | 1777 +---------------------------------------------------------------+ 1778 | .... | 1779 +---------------------------------------------------------------+ 1780 | .... | # of TE links | 1781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1782 | Link ID | 1783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1784 | Link Data | 1785 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1786 | Type | 0 | Link-TE options | 1787 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1788 | Link-TE flags | Zero or more Link-TE TLVs | 1789 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1790 | Link ID | 1791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1792 | Link Data | 1793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1794 | ... | 1796 10. Abstract topology representation with TE support 1798 Below, we consider a TE network composed of three OSPF areas - 1799 Area-1, Area-2 and Area-3, attached together through the backbone 1800 area. Area-1 an has a single area border router, ABR-A1 and no 1801 ASBRs. Area-2 has an area border router ABR-A2 and an AS border 1802 router ASBR-S1. Area-3 has two area border routers ABR-A2 and 1803 ABR-A3 and an AS border router ASBR-S2. The following network 1804 also assumes a pre-engineered TE circuit path between ABR-A1 1805 and ABR-A2; between ABR-A1 and ABR-A3; between ABR-A2 and 1806 ASBR-S1; and between ABR-A3 and ASBR-S2. 1808 The following figure is an inter-area topology abstraction 1809 from the perspective of routers in Area-1. The abstraction 1810 illustrates reachability of TE networks and nodes within area 1811 to the external areas in the same AS and to the external ASes. 1812 The abstraction also illustrates pre-engineered TE circuit 1813 paths advertised by ABRs and ASBRs. 1815 +-------+ 1816 |Area-1 | 1817 +-------+ 1818 +-------------+ | 1819 |Reachable TE | +--------+ 1820 |networks in |-------| ABR-A1 | 1821 |backbone area| +--------+ 1822 +-------------+ | | | 1823 +--------------+ | +-----------------+ 1824 | | | 1825 +-----------------+ | +-----------------+ 1826 |Pre-engineered TE| +----------+ |Pre-engineered TE| 1827 |circuit path(s) | | Backbone | |circuit path(s) | 1828 |to ABR-A2 | | Area | |to ABR-A3 | 1829 +-----------------+ +----------+ +-----------------+ 1830 | | | | 1831 +----------+ | +--------------+ | 1832 +-----------+ | | | | +-----------+ 1833 |Reachable | +--------+ +--------+ |Reachable | 1834 |TE networks|------| ABR-A2 | | ABR-A3 |--|TE networks| 1835 |in Area A2 | +--------+ +--------+ |in Area A3 | 1836 +-----------+ | | | | | | +-----------+ 1837 +-------------+ | | +-----------------+ | +----------+ 1838 | | +-----------+ | | | 1839 +-----------+ +--------------+ | | | +--------------+ 1840 |Reachable | |Pre-engineered| | | | |Pre-engineered| 1841 |TE networks| |TE Ckt path(s)| +------+ +------+ |TE Ckt path(s)| 1842 |in Area A3 | |to ASBR-S1 | |Area-2| |Area-3| |to ASBR-S2 | 1843 +-----------+ +--------------+ +------+ +------+ +--------------+ 1844 | | | | 1845 | +--------+ | +-----------+ 1846 +-------------+ | | | | 1847 |AS external | +---------+ +---------+ 1848 |TE-network |----| ASBR-S1 | | ASBR-S2 | 1849 |reachability | +---------+ +---------+ 1850 |from ASBR-S1 | | | | 1851 +-------------+ +---+ +-------+ +-----------+ 1852 | | | 1853 +-----------------+ +-------------+ +-----------------+ 1854 |Pre-engineered TE| |AS External | |Pre-engineered TE| 1855 |circuit path(s) | |TE-Network | |circuit path(s) | 1856 |reachable from | |reachability | |reachable from | 1857 |ASBR-S1 | |from ASBR-S2 | |ASBR-S2 | 1858 +-----------------+ +-------------+ +-----------------+ 1860 Figure 9: Inter-Area Abstraction as viewed by Area-1 TE-routers 1862 11. Changes to Data structures in OSPF-xTE nodes 1864 11.1. Changes to Router data structure 1866 An OSPF-xTE router must be able to include the router-TE 1867 capabilities (as specified in section 8.1) in the router data 1868 structure. OSPF-xTE routers providing proxy service to other TE 1869 routers must also track the router and associated interface data 1870 structures for all the TE client nodes for which the proxy 1871 service is being provided. Presumably, the interaction between 1872 the Proxy server and the proxy clients is out-of-band. 1874 11.2. Two sets of Neighbors 1876 Two sets of neighbor data structures are required. TE-neighbors 1877 set is used to advertise TE LSAs. Only the TE-nodes will be 1878 members of the TE-neighbor set. Native neighbors set will be used 1879 to advertise native LSAs. All neighboring nodes supporting 1880 non-TE links are part of the Native neighbors set. 1882 11.3. Changes to Interface data structure 1884 The following new fields are introduced to the interface data 1885 structure. 1887 TePermitted 1888 If the value of the flag is TRUE, the interface may be 1889 advertised as a TE-enabled interface. 1891 NonTePermitted 1892 If the value of the flag is TRUE, the interface permits non-TE 1893 traffic on the interface. Specifically, this is applicable to 1894 packet networks, where data links may permit both TE and IP 1895 packets. For FSC and LSC TE networks, this flag is set to 1896 FALSE. 1898 FloodingPermitted 1899 If the value of the flag is TRUE, the interface may be used 1900 for OSPF and OSPF-xTE packet exchange to synchronize the 1901 LSDB across all adjacent neighbors. This is TRUE by default 1902 to all NonTePermitted interfaces that are enabled for OSPF. 1903 However, it is possible to set this to FALSE 1904 for some of the interfaces. 1906 TE-TLVs 1907 Each interface may define any number of TLVS that describe 1908 the link characteristics. 1910 The following existing fields in Interface data structure will take 1911 on additional values to support TE extensions. 1913 Type 1914 The OSPF interface type can also be of type "Positional-RING". 1915 The Positional-ring type is different from other types (such 1916 as broadcast and NBMA) in that the exact location of the nodes 1917 on the ring is relevant, even though they are all on the same 1918 ring. SONET ADM ring is a good example of this. Complete ring 1919 positional-ring description may be provided by the GNE on a 1920 ring as a TE-network LSA for the ring. 1922 List of Neighbors 1923 The list may be statically defined for an interface without 1924 requiring the use of Hello protocol. 1926 12. IANA Considerations 1928 This document proposes that TE LSA types and TE TLVs be 1929 maintained by the IANA. The document also proposes an OSPFIGP-TE 1930 multicast address be assigned by the IANA for the exchange of 1931 TE database descriptors. 1933 OSPFIGP-TE multicast address is suggested a value of 224.0.0.24 1934 so as not to conflict with the recognized multicast address 1935 definitions, as defined in 1936 http://www.iana.org/assignments/multicast-addresses 1938 The following sub-section explains the criteria to be used by the 1939 IANA to assign TE LSA types and TE TLVs. 1941 12.1. TE LSA type values 1943 LSA type is an 8-bit field required by each LSA. TE LSA types 1944 will have the high bit set to 1. TE LSAs can range from 0x80 1945 through 0xFF. The following values are defined in sections 1946 8.0 and 9.0. The remaining values are available for assignment 1947 by the IANA with IETF Consensus [Ref 11]. 1949 TE LSA Type Value 1950 _________________________________________ 1951 TE-Router LSA 0x81 1952 TE-Positional-ring-network LSA 0x82 1953 TE-Summary Network LSA 0x83 1954 TE-Summary router LSA 0x84 1955 TE-AS-external LSAs 0x85 1956 TE-Circuit-paths LSA 0x8C 1957 TE-incremental-link-Update LSA 0x8d 1958 TE-Router-Proxy LSA 0x8e 1960 12.2. TE TLV tag values 1962 TLV type is a 16-bit field required by each TE TLV. TLV type 1963 shall be unique across the router and link TLVs. A TLV type 1964 can range from 0x0001 through 0xFFFF. TLV type 0 is reserved 1965 and unassigned. The following TLV types are defined in sections 1966 8.0 and 9.0. The remaining values are available for assignment 1967 by the IANA with IETF Consensus [Ref 11]. 1969 TE TLV Tag Reference Value 1970 Section 1971 _________________________________________________________ 1973 TE-LINK-TLV-SRLG Section 8.1.4.1 0x0001 1974 TE-LINK-TLV-BANDWIDTH-MAX Section 8.1.4.2 0x0002 1975 TE-LINK-TLV-BANDWIDTH-MAX-FOR-TE Section 8.1.4.3 0x0003 1976 TE-LINK-TLV-BANDWIDTH-TE Section 8.1.4.4 0x0004 1977 TE-LINK-TLV-LUG Section 8.1.4.5 0x0005 1978 TE-LINK-TLV-COLOR Section 8.1.4.6 0x0006 1979 TE-LINK-TLV-NULL Section 8.1.4.7 0x8888 1980 TE-NODE-TLV-MPLS-SWITCHING Section 8.1.2.1 0x8001 1981 TE-NODE-TLV-MPLS-SIG-PROTOCOLS Section 8.1.2.2 0x8002 1982 TE-NODE-TLV-CSPF-ALG Section 8.1.2.3 0x8003 1983 TE-NODE-TLV-NULL Section 8.1.2.4 0x8888 1985 13. Acknowledgements 1987 The authors wish to specially thank Chitti Babu and his team 1988 for implementing the protocol specified in a packet network 1989 and verifying several portions of the specification in a 1990 mixed packet network. The authors also wish to thank Vishwas 1991 Manral, Riyad Hartani and Tricci So for their valuable 1992 comments and feedback on the draft. Lastly, the authors wish 1993 to thank Alex Zinin and Mike Shand for their draft (now 1994 defunct) titled "Flooding optimizations in link state routing 1995 protocols". The draft provided inspiration to the authors to 1996 be sensitive to the high flooding rate, likely in TE networks. 1998 14. Security Considerations 2000 Security considerations for the base OSPF protocol are covered 2001 in [OSPF-v2] and [SEC-OSPF]. This memo does not create any new 2002 security issues for the OSPF protocol. Security measures 2003 applied to the native OSPF (refer [SEC-OSPF]) are directly 2004 applicable to the TE LSAs described in the document. Discussed 2005 below are the security considerations in processing TE LSAs. 2007 Secure communication between OSPF-xTE nodes has a number of 2008 components. Authorization, authentication, integrity and 2009 confidentiality. Authorization refers to whether a particular 2010 OSPF-xTE node is authorized to receive or propagate the TE LSAs 2011 to its neighbors. Failing the authorization process might 2012 indicate a resource theft attempt or unauthorized resource 2013 advertisement. In either case, the OSPF-xTE nodes should take 2014 proper measures to audit/log such attempts so as to alert the 2015 administrator to take necessary action. OSPF-xTE nodes may 2016 refuse to communicate with the neighboring nodes that fail to 2017 prompt the required credentials. 2019 Authentication refers to confirming the identity of an originator 2020 for the datagrams received from the originator. Lack of strong 2021 credentials for authentication of OSPF-xTE LSAs can seriously 2022 jeopardize the TE service rendered by the network. A consequence 2023 of not authenticating a neighbor would be that an attacker could 2024 spoof the identity of a "legitimate" OSPF-xTE node and manipulate 2025 the state, and the TE database including the topology and 2026 metrics collected. This could potentially cause 2027 denial-of-service on the TE network. Another consequence of not 2028 authenticating is that an attacker could pose as OSPF-xTE 2029 neighbor and respond in a manner that would divert TE data to the 2030 attacker. 2032 Integrity is required to ensure that an OSPF-xTE message has not 2033 been accidentally or maliciously altered or destroyed. The result 2034 of a lack of data integrity enforcement in an untrusted environment 2035 could be that an imposter will alter the messages sent by a 2036 legitimate adjacent neighbor and bring the OSPF-xTE on a node and 2037 the whole network to a halt or cause a denial of service for the 2038 TE circuit paths effected by the alteration. 2040 Confidentiality of MIDCOM messages ensure that the TE LSAs are 2041 accessible only to the authorized entities. When OSPF-xTE is 2042 deployed in an untrusted environment, lack of confidentiality will 2043 allow an intruder to perform traffic flow analysis and snoop the 2044 TE control network to monitor the traffic metrics and the rate at 2045 which circuit paths are being setup and torn-down. The intruder 2046 could cannibalize a lesser secure OSPF-xTE node and destroy or 2047 compromise the state and TE-LDSB on the node. Needless to say, the 2048 least secure OSPF-xTE will become the Achilles heel and make the 2049 TE network vulnerable to security attacks. 2051 15. Normative References 2053 [IETF-STD] Bradner, S., "Key words for use in RFCs to indicate 2054 Requirement Levels", BCP 14, RFC 2119, March 1997. 2056 [RFC 1700] J. Reynolds and J. Postel, "Assigned Numbers", 2057 RFC 1700 2059 [RFC 2434] Narten, T. and H. Alvestrand, "Guidelines for 2060 writing an IANA Considerations Section in RFCs", 2061 BCP 26, RFC 2434, October 1998. 2063 [MPLS-TE] Awduche, D., et al, "Requirements for Traffic 2064 Engineering Over MPLS," RFC 2702, September 1999. 2066 [OSPF-v2] Moy, J., "OSPF Version 2", RFC 2328, April 1998. 2068 [SEC-OSPF] Murphy, S., Badger, M., and B. Wellington, "OSPF with 2069 Digital Signatures", RFC 2154, June 1997 2071 16. Informative References 2073 [RSVP-TE] Awduche, D., L. Berger, D. Gan, T. Li, V. Srinivasan, 2074 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 2075 Tunnels", RFC 3209, IETF, December 2001 2077 [CR-LDP] Jamoussi, B. et al, "Constraint-Based LSP Setup 2078 using LDP", RFC 3212, January 2002. 2080 [MOSPF] Moy, J., "Multicast Extensions to OSPF", RFC 1584, 2081 March 1994. 2083 [NSSA] P. Murphy, "The OSPF NSSA Option", RFC 3101, January 2084 2003 2086 [OPAQUE] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, 2087 July 1998. 2089 [OPQLSA-TE] Katz, D., D. Yeung and K. Kompella, "Traffic 2091 Engineering Extensions to OSPF", RFC 3630, September 2092 2003. 2094 [SONET-SDH] Ming-CHwan Chow, "Understanding SONET/SDH Standards 2095 and Applications" - A paperback or bound book, 2096 Published by Andan publisher. 2098 [GMPLS-TE] L. Berger, "Generalized Multi Protocol Label 2099 Switching (GMPLS) Signaling Functional Description", 2100 RFC 3471, January 2003 2102 Authors' Addresses 2104 Pyda Srisuresh 2105 Caymas Systems, Inc. 2106 1179-A North McDowell Blvd. 2107 Petaluma, CA 94954 2108 U.S.A. 2109 EMail: srisuresh@yahoo.com 2111 Paul Joseph 2112 Force10 Networks 2113 1440 McCarthy Boulevard 2114 Milpitas, CA 95035 2115 U.S.A. 2116 EMail: pjoseph@Force10Networks.com