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Nadeau 3 Cisco Systems, Inc. 5 Angela Chiu 6 AT&T 8 William Townsend 9 Tenor Networks 11 Darek Skalecki 12 Nortel Networks 14 IETF Internet Draft 15 Expires: May, 2001 16 Document: draft-lefaucheur-diff-te-ospf-00.txt November, 2000 18 Extensions to OSPF 19 for support of Diff-Serv-aware MPLS Traffic Engineering 21 Status of this Memo 23 This document is an Internet-Draft and is in full conformance with 24 all provisions of Section 10 of RFC2026. Internet-Drafts are 25 Working documents of the Internet Engineering Task Force (IETF), its 26 areas, and its working groups. Note that other groups may also 27 distribute working documents as Internet-Drafts. 29 Internet-Drafts are draft documents valid for a maximum of six 30 months and may be updated, replaced, or obsoleted by other documents 31 at any time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 The list of current Internet-Drafts can be accessed at 35 http://www.ietf.org/ietf/1id-abstracts.txt. 36 The list of Internet-Draft Shadow Directories can be accessed at 37 http://www.ietf.org/shadow.html. 39 Abstract 41 A companion document [DIFF-TE-REQTS] defines the requirements for 42 support of Diff-Serv-aware MPLS Traffic Engineering on a per-Class- 43 Type basis, as discussed in the Traffic Engineering Working Group 44 Framework document [TEWG-FW]. 46 This document proposes corresponding extensions to OSPF for support 47 of Traffic Engineering on a per-Class-Type basis. 49 Le Faucheur, et. al 1 50 Two companion documents [DIFF-TE-EXT] [DIFF-TE-ISIS] propose 51 corresponding extensions to RSVP and CR-LDP and to ISIS for support 52 of Traffic Engineering on a per-Class-Type basis. 54 1. Introduction 56 As Diffserv becomes prominent in providing scalable multi-class of 57 services in IP networks, performing traffic engineering at a per- 58 class level instead of an aggregated level is needed to further 59 enhance networks in performance and efficiency. By mapping a traffic 60 trunk in a given class on a separate LSP, it allows the traffic 61 trunk to utilize resources available on both shortest path(s) and 62 non-shortest paths and follow paths that meet constraints which are 63 specific to the given class. It also allows each class to select the 64 proper protection/restoration mechanism(s) that satisfy its 65 survivability requirements in a cost effective manner. 67 Besides the set of parameters defined for the general aggregate TE 68 [TE-REQ], a new set of per-class parameters needs to be provided at 69 each LSR interface and propagated via extensions to the IGP 70 (ISIS/OSPF) [TEWG-FW]. Furthermore, the per-class parameters can be 71 aggregated into per-Class-Type parameters. The main motivation for 72 grouping a set of classes into a Class-Type is to improve the 73 scalability of the IGP link state advertisements by propagating 74 information on a per-Class-Type basis instead of on a per-class 75 basis. This approach also has the benefit of allowing better 76 bandwidth sharing between classes in the same Class-Type. 78 A Class-Type [TEWG-FW] is defined as a set of classes that satisfy 79 the following two conditions: 81 1) Classes in the same Class-Type possess common aggregate maximum 82 and minimum bandwidth requirements to guarantee the required 83 performance level. 85 2) There is no maximum or minimum bandwidth requirement to be 86 enforced at the level of an individual class within the Class- 87 Type. One can still implement some "priority" policies for 88 classes within the same Class-Type in terms of accessing the 89 Class-Type bandwidth (e.g. via the use of preemption 90 priorities). 92 An example of Class-Type comprising multiple Diff-Serv classes is a 93 low-loss Class-Type that includes both AF1-based and AF2-based 94 Ordering Aggregates. 96 Note that with per Class-Type TE, Constraint-Based Routing is 97 performed with bandwidth constraints on a per Class-Type basis but 98 LSPs may carry a single Diff-Serv class (Ordered Aggregate) with 99 Diff-Serv scheduling (i.e. PHB) performed separately for each class. 101 Le Faucheur et. al 2 102 In this document, we will only discuss "per Class-Type TE" because 103 "per Class TE" can be viewed as a special case of per Class-Type TE 104 (where each Class-Type is degenerated into a single Diff-Serv 105 class). 107 This document focuses on intra-domain operations. Inter-domain 108 operations is for further study. 110 A companion document [DIFF-TE-REQTS] defines the requirements for 111 support of MPLS Traffic Engineering on a per-Class-Type basis. The 112 following sections propose detailed extensions to OSPF that meet 113 those requirements. 115 Two companion documents [DIFF-TE-EXT] [DIFF-TE-ISIS] propose 116 corresponding extensions to RSVP and CR-LDP and to ISIS for support 117 of Traffic Engineering on a per-Class-Type basis. 119 2. OSPF Extensions 121 In this section we propose extensions to OSPF for support of Diff- 122 Serv Traffic Engineering on a per-Class-Type basis which meet the 123 requirements defined in [DIFF-TE-REQTS]. These extensions are in 124 addition to the extensions already defined for support of 125 (aggregate) MPLS Traffic Engineering in [OSPF-TE]. 127 2.1. Existing TE Sub-TLVs 129 [OSPF-TE] defines a new LSA for support of (aggregate) Traffic 130 Engineering, which is referred to as the Traffic Engineering LSA. 131 This LSA contains a Link TLV (Type 2) comprising a number of sub- 132 TLVs. 134 In this document we refer to the sub-TLV 7 (maximum reservable 135 bandwidth) of the Link TLV (as defined in [OSPF-TE]) as the "Maximum 136 Reservable Aggregate Bandwidth". 138 We also refer to the sub-TLV 8 (unreserved bandwidth) of the Link 139 TLV (as defined in [OSPF-TE]) as the "Unreserved Bandwidth for 140 Class-Type 0". 142 2.2. New Sub-TLVs 144 The following additional sub-TLVs are defined for the Link TLV of 145 the Traffic Engineering LSA (sub-TLV numbers to be allocated) 147 TBD1 - Unreserved Bandwidth for Class-Type 1 (32 octets) 148 TBD2 - Unreserved Bandwidth for Class-Type 2 (32 octets) 149 TBD3 - Unreserved Bandwidth for Class-Type 3 (32 octets) 151 Each sub-TLV may occur only once. Unrecognized types are ignored. 153 Le Faucheur et. al 3 154 Unlike the sub-TLVs defined for the Link TLV in [OSPF-TE], the 155 additional sub-TLVs defined above are optional. 157 The Link TLV may include the sub-TLVs for any subset of the three 158 additional Class-Types. In other words, the Link TLV may contain 159 none of the three sub-TLVs defined above, any one of those, any two 160 of those, or the three sub-TLVs. 162 As discussed in [DIFF-TE-REQTS], where a Class-Type is not 163 effectively used in a network, it is recommended that the 164 corresponding sub-TLV is not included in the Link TLV. Therefore, 165 the Class-Types to be advertised in OSPF should be configurable. For 166 instance, a Network Administrator may elect to use Diff-Serv Traffic 167 Engineering in order to compute separate routes for data traffic and 168 voice traffic (and apply different bandwidth constraints to the 169 route computation for those). In that case, the IGP would only 170 advertise the sub-TLV for one additional Class-Type (i.e. the Link 171 TLV would contain sub-TLV 7 for the Maximum Reservable Aggregate 172 Bandwidth, sub-TLV 8 for the Unreserved Bandwidth for Class-Type 0 173 and sub-TLV TBD1 for Unreserved Bandwidth for Class-Type 1). 175 An LSR which supports Class-Type N and which receives a Link TLV 176 without the sub-TLV corresponding to Class-Type N, interprets this 177 as meaning that the corresponding link does not support Class-Type 178 N. For Constraint Based Routing purposes, the LSR may consider this 179 equivalent to the case where the Link TLV contains an Unreserved 180 Bandwidth for Class-Type N sub-TLV set to zero. 182 An LSR which does not support Class-Type N and which receives a Link 183 TLV containing the sub-TLV corresponding to Class-Type N, must 184 ignore this sub-TLV. However, the Link TLV must be flooded 185 transparently, so that the sub-TLV for Class-Type N is kept in the 186 Link TLV when reflooded by this LSR. 188 2.3. Sub-TLV Details 190 The Unreserved Bandwidth for Class-Type N (N= 1,2,3) sub-TLV 191 specifies the amount of bandwidth not yet reserved at each of the 192 eight preemption priority levels for Class-Type N. Each value will 193 be less than or equal to the Maximum Reservable Bandwidth for Class- 194 Type N. 196 When the bandwidth value for preemption Z (Z > 0) is identical to 197 the bandwidth value for preemption Z-1, the bandwidth value for 198 preemption Z is not explicitly repeated in the sub-TLV. Rather, the 199 fact that it is identical to the value of preemption Z-1, is encoded 200 in a "repetition octet". 202 Thus, the sub-TLV comprises: 204 Le Faucheur et. al 4 205 - P (1<=P<=8) bandwidth values. These values correspond to the 206 bandwidth that can be reserved with a holding priority of 0 through 207 7, arranged in increasing order with priority 0 occurring at the 208 start of the sub-TLV, and priority 7 towards the end of the sub-TLV, 209 but omitting all repeated values. The units are bytes per second and 210 the values are encoded in IEEE floating point format. 212 - a "repetition octet" where each bit is referred to as bitZ , 213 0 <= Z < 8, and is defined to have the following meaning: 214 * if bitZ = 0 then "Unreserved Bandwidth" for preemption 215 level Z is explicitely included in the sub-TLV, 216 * if bitZ = 1 then "Unreserved Bandwidth" for preemption 217 level Z is not explicitely included in the sub-TLV but is 218 defined to be equal to "Unreserved Bandwidth" for preemption 219 level Z-1. 221 Note that the highest preemption level (level 0) is always 222 advertised and the first bit (Bit0) in the "repetition octet" is 223 always set to 0. 225 [Editor's note: should the "repetition octet" be moved before the 226 bandwidth values?] 228 The Unreserved Bandwidth for Class-Type N sub-TLV is TLV type 229 (TBDN). Its length is (P*4 +1), where 1<=P<=8 and where P is the 230 number of non-equal bandwidth values across all preemption levels 231 for that Class-Type. 233 For example, when a link supports LSPs of preemption levels 2 and 4 234 only (for a particular Class-Type) with "Unreserved Bandwidth" (for 235 the particular Class-Type) on that link for preemption levels 0, 2, 236 and 4 currently of 10Mb/s, 5Mb/s and 3Mb/s, respectively, then 237 "Unreserved Bandwidth" (for the particular Class-Type) for 238 preemption levels 0, 2, and 4 of 10Mb/s, 5Mb/s and 3Mb/s, 239 respectively, are explicitly advertised for that link as well as 240 "repetition octet" of 01010111 in binary form. The sub-TLV length is 241 13. 243 3. Security Considerations 245 This document raises no new security issues for OSPF. The security 246 mechanisms already proposed for OSPF may be used. 248 4. Acknowledgments 250 Le Faucheur et. al 5 251 This document has benefited from discussions with Carol Iturralde. 253 References 255 [TE-REQ] Awduche et al, Requirements for Traffic Engineering over 256 MPLS, RFC2702, September 1999. 258 [TEWG-FW] Awduche et al, A Framework for Internet Traffic 259 Engineering, draft-ietf-tewg-framework-02.txt, July 2000. 261 [DIFF-TE-REQTS] Le Faucheur et al, Requirements for support of 262 Diff-Serv-aware MPLS Traffic Engineering, draft-ietf-mpls-diff-te- 263 reqts-00.txt, November 2000. 265 [DIFF-TE-EXT] Le Faucheur et al, Extension to RSVP and CR-LDP for 266 support of Diff-Serv-aware MPLS Traffic Engineering, draft-ietf- 267 mpls-diff-te-ext-00.txt, November 2000. 269 [DIFF-TE-ISIS] Le Faucheur et al, Extension to ISIS for support of 270 Diff-Serv-aware MPLS Traffic Engineering, draft-lefaucheur-diff-te- 271 isis-01.txt, November 2000. 273 [OSPF-TE] Katz, Yeung, Traffic Engineering Extensions to OSPF, 274 draft-katz-yeung-ospf-traffic-03.txt, September 2000. 276 [ISIS-TE] Smit, Li, IS-IS extensions for Traffic Engineering, draft- 277 ietf-isis-traffic-02.txt, September 2000. 279 Authors' Address: 281 Francois Le Faucheur 282 Cisco Systems, Inc. 283 Petra B - Les Lucioles - 291, rue Albert Caquot - 06560 Valbonne - 284 France 285 Phone: +33 4 92 96 75 64 286 Email: flefauch@cisco.com 288 Angela Chiu 289 AT&T Labs 290 200 Laurel Ave. Rm A5-1F06 291 Middletown, NJ 07748, USA 292 Tel: 1-(732) 420-9057 293 Email: alchiu@att.com 295 William Townsend 296 Tenor Networks 297 100 Nagog Park 298 Acton, MA 01720 300 Le Faucheur et. al 6 301 Phone: +1-978-264-4900 302 Email: btownsend@tenornetworks.com 304 Thomas D. Nadeau 305 Cisco Systems, Inc. 306 250 Apollo Drive 307 Chelmsford, MA 01824 308 Phone: +1-978-244-3051 309 Email: tnadeau@cisco.com 311 Darek Skalecki 312 Nortel Networks 313 3500 Carling Ave, 314 Nepean K2H 8E9 315 Phone: +1-613-765-2252 316 Email: dareks@nortelnetworks.com 318 Le Faucheur et. al 7