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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Cheng 3 Internet-Draft Huawei 4 Intended status: Standards Track J. Korhonen 5 Expires: October 24, 2015 Broadcom Corporation 6 M. Boucadair 7 France Telecom 8 S. Sivakumar 9 Cisco Systems 10 April 22, 2015 12 RADIUS Extensions for IP Port Configuration and Reporting 13 draft-ietf-radext-ip-port-radius-ext-04 15 Abstract 17 This document defines three new RADIUS attributes. For devices that 18 implementing IP port ranges, these attributes are used to communicate 19 with a RADIUS server in order to configure and report TCP/UDP ports 20 and ICMP identifiers, as well as mapping behavior for specific hosts. 21 This mechanism can be used in various deployment scenarios such as 22 CGN (Carrier Grade NAT), NAT64, Provider WLAN Gateway, etc. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 28 document are to be interpreted as described in RFC 2119 [RFC2119]. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on October 24, 2015. 47 Copyright Notice 49 Copyright (c) 2015 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 3. Extensions of RADIUS Attributes and TLVs . . . . . . . . . . 5 67 3.1. Extended Attributes for IP Ports . . . . . . . . . . . . 6 68 3.1.1. IP-Port-Limit Attribute . . . . . . . . . . . . . . . 6 69 3.1.2. IP-Port-Range Attribute . . . . . . . . . . . . . . . 7 70 3.1.3. IP-Port-Forwarding-Map Attribute . . . . . . . . . . 10 71 3.2. RADIUS TLVs for IP Ports . . . . . . . . . . . . . . . . 12 72 3.2.1. IP-Port-Type TLV . . . . . . . . . . . . . . . . . . 12 73 3.2.2. IP-Port-Limit TLV . . . . . . . . . . . . . . . . . . 13 74 3.2.3. IP-Port-Ext-IPv4-Addr TLV . . . . . . . . . . . . . . 14 75 3.2.4. IP-Port-Int-IPv4-Addr TLV . . . . . . . . . . . . . . 15 76 3.2.5. IP-Port-Int-IPv6-Addr TLV . . . . . . . . . . . . . . 16 77 3.2.6. IP-Port-Int-Port TLV . . . . . . . . . . . . . . . . 16 78 3.2.7. IP-Port-Ext-Port TLV . . . . . . . . . . . . . . . . 17 79 3.2.8. IP-Port-Alloc TLV . . . . . . . . . . . . . . . . . . 18 80 3.2.9. IP-Port-Range-Start TLV . . . . . . . . . . . . . . . 19 81 3.2.10. IP-Port-Range-End TLV . . . . . . . . . . . . . . . . 20 82 3.2.11. IP-Port-Local-Id TLV . . . . . . . . . . . . . . . . 21 83 4. Applications, Use Cases and Examples . . . . . . . . . . . . 22 84 4.1. Managing CGN Port Behavior using RADIUS . . . . . . . . . 22 85 4.1.1. Configure IP Port Limit for a User . . . . . . . . . 23 86 4.1.2. Report IP Port Allocation/De-allocation . . . . . . . 25 87 4.1.3. Configure Forwarding Port Mapping . . . . . . . . . . 26 88 4.1.4. An Example . . . . . . . . . . . . . . . . . . . . . 28 89 4.2. Report Assigned Port Set for a Visiting UE . . . . . . . 29 90 5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 30 91 6. Security Considerations . . . . . . . . . . . . . . . . . . . 31 92 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 93 7.1. IANA Considerations on New IPFIX Elements . . . . . . . . 31 94 7.2. IANA Considerations on New RADIUS Attributes . . . . . . 32 96 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33 97 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 33 98 9.1. Normative References . . . . . . . . . . . . . . . . . . 33 99 9.2. Informative References . . . . . . . . . . . . . . . . . 34 100 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 102 1. Introduction 104 In a broadband network, customer information is usually stored on a 105 RADIUS server [RFC2865] and at the time when a user initiates an IP 106 connection request, the RADIUS server will populate the user's 107 configuration information to the Network Access Server (NAS), which 108 is usually co-located with the Border Network Gateway (BNG), after 109 the connection request is granted. The Carrier Grade NAT (CGN) 110 function may also be implemented on the BNG, and therefore the CGN 111 TCP/UDP port (or ICMP identifier) mapping(s) behavior(s) can be 112 configured on the RADIUS server as part of the user profile, and 113 populated to the NAS in the same manner. In addition, during the 114 operation, the CGN can also convey port/identifier mapping behavior 115 specific to a user to the RADIUS server, as part of the normal RADIUS 116 accounting process. 118 The CGN device that communicates with a RADIUS server using RADIUS 119 extensions defined in this document may perform NAT44 [RFC3022], 120 NAT64 [RFC6146], or Dual-Stack Lite AFTR [RFC6333] function. 122 For the CGN case, when IP packets traverse a CGN device, it would 123 perform TCP/UDP source port mapping or ICMP identifier mapping as 124 required. A TCP/ UDP source port or ICMP identifier, along with 125 source IP address, destination IP address, destination port and 126 protocol identifier if applicable, uniquely identify a session. 127 Since the number space of TCP/UDP ports and ICMP identifiers in CGN's 128 external realm is shared among multiple users assigned with the same 129 IPv4 address, the total number of a user's simultaneous IP sessions 130 is likely to be subject to port quota (see Section 5 of [RFC6269]). 132 The attributes defined in this document may also be used to report 133 the assigned port range in some deployments such as Provider WLAN 134 [I-D.gundavelli-v6ops-community-wifi-svcs]. For example, a visiting 135 host can be managed by a CPE (Customer Premises Equipment ) which 136 will need to report the assigned port range to the service platform. 137 This is required for identification purposes (see TR-146 [TR-146] for 138 example). 140 This document proposes three new attributes as RADIUS protocol's 141 extensions, and they are used for separate purposes as follows: 143 1. IP-Port-Limit: This attribute may be carried in RADIUS Acces- 144 Accept, Access-Request, Accounting-Request or CoA-Request packet. 145 The purpose of this attribute is to limit the total number of 146 TCP/UDP ports and/or ICMP identifiers that an IP subscriber can 147 use, associated with one or more IPv4 addresses. 149 2. IP-Port-Range: This attribute may be carried in RADIUS 150 Accounting-Request packet. The purpose of this attribute is to 151 report by an address sharing device (e.g., a CGN) to the RADIUS 152 server the range of TCP/UDP ports and/or ICMP identifiers that 153 have been allocated or deallocated associated with a given IPv4 154 address for a subscriber. 156 3. IP-Port-Forwarding-Map: This attribute may be carried in RADIUS 157 Access-Accept, Access-Request, Accounting-Request or CoA-Request 158 packet. The purpose of this attribute is to specify how a TCP/ 159 UDP port (or an ICMP identifier) mapping to another TCP/UDP port 160 (or an ICMP identifier), and each is associated with its 161 respective IPv4 address. 163 This document leverages the protocol defined in [RFC7012] by 164 proposing a mapping between type field of RADIUS TLV and Element ID 165 of IPFIX. It also proposes a few new IPFIX Elements as required by 166 this document (see Section 3). 168 This document was constructed using the [RFC2629]. 170 2. Terminology 172 This document makes use if the following terms: 174 o IP Port: refers to the port numbers of IP transport protocols, 175 including TCP port, UDP port and ICMP identifier. 177 o IP Port Type: refers to one of the following: (1) TCP/UDP port and 178 ICMP identifier, (2) TCP port and UDP port, (3) TCP port, (4) UDP 179 port, or (5) ICMP identifier. 181 o IP Port Limit: denotes the maximum number of IP ports for a 182 specific IP port type, that a device supporting port ranges can 183 use when performing port number mapping for a specific user. 184 Note, this limit is usually associated with one or more IPv4 185 addresses. 187 o IP Port Range: specifies a set of contiguous IP ports, indicated 188 by the smallest numerical number and the largest numerical number, 189 inclusively. 191 o Internal IP Address: refers to the IP address that is used as a 192 source IP address in an outbound IP packet sent towards a device 193 supporting port ranges in the internal realm. In the IPv4 case, 194 it is typically a private address [RFC1918]. 196 o External IP Address: refers to the IP address that is used as a 197 source IP address in an outbound IP packet after traversing a 198 device supporting port ranges in the external realm. In the IPv4 199 case, it is typically a global routable IP address. 201 o Internal Port: is a UDP or TCP port, or an ICMP identifier, which 202 is allocated by a host or application behind a device supporting 203 port ranges for an outbound IP packet in the internal realm. 205 o External Port: is a UDP or TCP port, or an ICMP identifier, which 206 is allocated by a device supporting port ranges upon receiving an 207 outbound IP packet in the internal realm, and is used to replace 208 the internal port that is allocated by a user or application. 210 o External realm: refers to the networking segment where IPv4 public 211 addresses are used in respective of the device supporting port 212 ranges. 214 o Internal realm: refers to the networking segment that is behind a 215 device supporting port ranges and where IPv4 private addresses are 216 used. 218 o Mapping: associates with a device supporting port ranges for a 219 relationship between an internal IP address, internal port and the 220 protocol, and an external IP address, external port, and the 221 protocol. 223 o Port-based device: a device that is capable of providing IP 224 address and IP port mapping services and in particular, with the 225 granularity of one or more subsets within the 16-bit IP port 226 number range. A typical example of this device is a CGN, CPE, 227 Provider WLAN Gateway, etc. 229 Note the terms "internal IP address", "internal port", "internal 230 realm", "external IP address", "external port", "external realm", and 231 "mapping" and their semantics are the same as in [RFC6887], and 232 [RFC6888]. 234 3. Extensions of RADIUS Attributes and TLVs 236 These three new attributes are defined in the following sub-sections: 238 1. IP-Port-Limit Attribute 239 2. IP-Port-Range Attribute 241 3. IP-Port-Forwarding-Map Attribute 243 All these attributes are allocated from the RADIUS "Extended Type" 244 code space per [RFC6929]. 246 3.1. Extended Attributes for IP Ports 248 3.1.1. IP-Port-Limit Attribute 250 This attribute is RADIUS Extended-Type, and contains a set of 251 embedded TLVs defined in Section 3.2.1 (IP-Port-Type TLV), 252 Section 3.2.2 (IP-Port-Limit TLV), and Section 3.2.3 (IP-Port-Ext- 253 IPv4-Addr TLV). It specifies the maximum number of IP ports as 254 indicated in IP-Port-Limit TLV, of a specific port type as indicated 255 in IP-Port-Type TLV, and associated with a given IPv4 address as 256 indicated in IP-Port-Ext-IPv4-Addr TLV for an end user. 258 Note that when IP-Port-Ext-IPv4-Addr TLV is not included as part of 259 the IP-Port-Limit Attribute, the port limit is applied to all the 260 IPv4 addresses managed by the port device, e.g., a CGN or NAT64 261 device. 263 The IP-Port-Limit Attribute MAY appear in an Access-Accept packet. 264 It MAY also appear in an Access-Request packet as a hint by the 265 device supporting port ranges, which is co-allocated with the NAS, to 266 the RADIUS server as a preference, although the server is not 267 required to honor such a hint. 269 The IP-Port-Limit Attribute MAY appear in a CoA-Request packet. 271 The IP-Port-Limit Attribute MAY appear in an Accounting-Request 272 packet. 274 The IP-Port-Limit Attribute MUST NOT appear in any other RADIUS 275 packets. 277 The format of the IP-Port-Limit Attribute is shown in Figure 1. The 278 fields are transmitted from left to right. 280 0 1 2 3 281 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 1 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 | Type | Length | Extended-Type | Value ... 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 Figure 1 288 Type: 290 TBA1. 292 Length: 294 This field indicates the total length in bytes of all fields of 295 this attribute, including the Type, Length, Extended-Type, and the 296 entire length of the embedded TLVs. 298 Extended-Type: 300 TBA2. 302 Value: 304 This field contains a set of TLVs as follows: 306 IP-Port-Type TLV: 308 This TLV contains a value that indicates the IP port type. 309 Refer to Section 3.2.1. 311 IP-Port-Limit TLV: 313 This TLV contains the maximum number of IP ports of a specific 314 IP port type and associated with a given IPv4 address for an 315 end user. This TLV must be included in the IP-Port-Limit 316 Attribute. Refer to Section 3.2.2. 318 IP-Port-Ext-IPv4-Addr TLV: 320 This TLV contains the IPv4 address that is associated with the 321 IP port limit contained in the IP-Port-Limit TLV. This TLV is 322 optionally included as part of the IP-Port-Limit Attribute. 323 Refer to Section 3.2.3. 325 IP-Port-Limit attribute is associated with the following identifier: 326 Type(TBA1).Extended-Type(TBA2).[IP-Port-Limit TLV (TBA6),IP-Port-Type 327 TLV(TBA5), {IP-Port-Ext-IPv4-Addr TLV(TBA7)}]. 329 3.1.2. IP-Port-Range Attribute 331 This attribute is RADIUS Extended-Type, and contains a set of 332 embedded TLVs defined in Section 3.2.1(IP-Port-Type TLV), Section 333 3.2.9(IP-Port-Range-Start TLV), Section 3.2.10 (IP-Port-Range-End 334 TLV), Section 3.2.8 (IP-Port-Alloc TLV), Section 3.2.3 (IP-Port-Ext- 335 IPv4-Addr TLV), and Section 3.2.11 (IP-Port-Local-Id TLV). 337 This attribute contains a range of contiguous IP ports of a specific 338 port type and associated with an IPv4 address that are either 339 allocated or deallocated by a device for a given subscriber, and the 340 information is intended to send to RADIUS server. 342 This attribute can be used to convey a single IP port number; in such 343 case IP-Port-Range-Start and IP-Port-Range-End conveys the same 344 value. 346 Within an IP-Port-Range Attribute, the IP-Port-Alloc TLV is always 347 included. For port allocation, both IP-Port-Range-Start TLV and IP- 348 Port-Range-End TLV must be included; for port deallocation, the 349 inclusion of these two TLVs is optional and if not included, it 350 implies that all ports that are previously allocated are now 351 deallocated. Both IP-Port-Ext-IPv4-Addr TLV and IP-Port-Local-Id TLV 352 are optional and if included, they are used by a port device (e.g., a 353 CGN device) to identify the end user. 355 The IP-Port-Range Attribute MAY appear in an Accounting-Request 356 packet. 358 The IP-Port-Range Attribute MUST NOT appear in any other RADIUS 359 packets. 361 The format of the IP-Port-Range Attribute format is shown in 362 Figure 2. The fields are transmitted from left to right. 364 0 1 2 3 365 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 1 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 367 | Type | Length | Extended-Type | Value ... 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 370 Figure 2 372 Type: 374 TBA1. 376 Length: 378 This field indicates the total length in bytes of all fields of 379 this attribute, including the Type, Length, Extended-Type, and the 380 entire length of the embedded TLVs. 382 Extended-Type: 384 TBA3. 386 Value: 388 This field contains a set of TLVs as follows: 390 IP-Port-Type TLV: 392 This TLV contains a value that indicates the IP port type. 393 Refer to Section 3.2.1. 395 IP-Port-Alloc TLV: 397 This TLV contains a flag to indicate that the range of the 398 specified IP ports for either allocation or deallocation. This 399 TLV must be included as part of the IP-Port-Range Attribute. 400 Refer to Section 3.2.8. 402 IP-Port-Range-Start TLV: 404 This TLV contains the smallest port number of a range of 405 contiguous IP ports. To report the port allocation, this TLV 406 must be included together with IP-Port-Range-End TLV as part of 407 the IP-Port-Range Attribute. Refer to Section 3.2.9. 409 IP-Port-Range-End TLV: 411 This TLV contains the largest port number of a range of 412 contiguous IP ports. To report the port allocation, this TLV 413 must be included together with IP-Port-Range-Start TLV as part 414 of the IP-Port-Range Attribute. Refer to Section 3.2.10. 416 IP-Port-Ext-IPv4-Addr TLV: 418 This TLV contains the IPv4 address that is associated with the 419 IP port range, as collectively indicated in the IP-Port-Range- 420 Start TLV and the IP-Port-Range-End TLV. This TLV is 421 optionally included as part of the IP-Port-Range Attribute. 422 Refer to Section 3.2.3. 424 IP-Port-Local-Id TLV: 426 This TLV contains a local session identifier at the customer 427 premise, such as MAC address, interface ID, VLAN ID, PPP 428 sessions ID, VRF ID, IPv6 address/prefix, etc. This TLV is 429 optionally included as part of the IP-Port-Range Attribute. 430 Refer to Section 3.2.11. 432 The IP-Port-Range attribute is associated with the following 433 identifier: Type(TBA1).Extended-Type(TBA3).[IP-Port-Alloc TLV 434 (TBA12), IP-Port-Type TLV(TBA5), {IP-Port-Range-Start TLV(TBA13), IP- 435 Port-Range-End TLV(TBA14)}, {IP-Port-Ext-IPv4-Addr TLV (TBA7)}, {IP- 436 Port-Local-Id TLV (TBA15)}]. 438 3.1.3. IP-Port-Forwarding-Map Attribute 440 This attribute is RADIUS Extended-Type, and contains a set of 441 embedded TLVs defined in Section 3.2.1(IP-Port-Type TLV), Section 442 3.2.6(IP-Port-Int-Port TLV), Section 3.2.7(IP-Port-Ext-Port TLV), 443 Section 3.2.4(IP-Port-Int-IPv4-Addr TLV) or Section 3.2.5(IP-Port- 444 Int-IPv6-Addr TLV), Section 3.2.11(IP-Port-Local-Id TLV) and 445 Section 3.2.3 (IP-Port-Ext-IP-Addr TLV). 447 The attribute contains a 2-byte IP internal port number that is 448 associated with an internal IPv4 or IPv6 address, or a locally 449 significant identifier at the customer site, and a 2-byte IP external 450 port number that is associated with an external IPv4 address. The 451 internal IPv4 or IPv6 address, or the local identifier must be 452 included; the external IPv4 address may also be included. 454 The IP-Port-Forwarding-Map Attribute MAY appear in an Access-Accept 455 packet. It MAY also appear in an Access-Request packet as a hint by 456 the device supporting port mapping, which is co-allocated with the 457 NAS, to the RADIUS server as a preference, although the server is not 458 required to honor such a hint. 460 The IP-Port-Forwarding-Map Attribute MAY appear in a CoA-Request 461 packet. 463 The IP-Port-Forwarding-Map Attribute MAY also appear in an 464 Accounting-Request packet. 466 The attribute MUST NOT appear in any other RADIUS packet. 468 The format of the IP-Port-Forwarding-Map Attribute is shown in 469 Figure 3. The fields are transmitted from left to right. 471 0 1 2 3 472 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 1 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 | Type | Length | Extended-Type | Value .... 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 Figure 3 479 Type: 481 TBA1. 483 Length: 485 This field indicates the total length in bytes of all fields of 486 this attribute, including the Type, Length, Extended-Type, and the 487 entire length of the embedded TLVs. 489 Extended-Type: 491 TBA4. 493 Value: 495 This field contains a set of TLVs as follows: 497 IP-Port-Type TLV: 499 This TLV contains a value that indicates the IP port type. 500 Refer to Section 3.2.1. 502 IP-Port-Int-Port TLV: 504 This TLV contains an internal IP port number associated with an 505 internal IPv4 or IPv6 address. This TLV must be included 506 together with IP-Port-Ext-Port TLV as part of the IP-Port- 507 Forwarding-Map attribute. Refer to Section 3.2.6. 509 IP-Port-Ext-Port TLV: 511 This TLV contains an external IP port number associated with an 512 external IPv4 address. This TLV must be included together with 513 IP-Port-Int-Port TLV as part of the IP-Port-Forwarding-Map 514 attribute. Refer to Section 3.2.7. 516 IP-Port-Int-IPv4-Addr TLV: 518 This TLV contains an IPv4 address that is associated with the 519 internal IP port number contained in the IP-Port-Int-Port TLV. 520 For IPv4 network, either this TLV or IP-Port-Local-Id TLV must 521 be included as part of the IP-Port-Forwarding-Map Attribute. 522 Refer to Section 3.2.4. 524 IP-Port-Int-IPv6-Addr TLV: 526 This TLV contains an IPv4 address that is associated with the 527 internal IP port number contained in the IP-Port-Int-Port TLV. 528 For IPv6 network, either this TLV or IP-Port-Local-Id TLV must 529 be included as part of the IP-Port-Forwarding-Map Attribute. 530 Refer to Section 3.2.5. 532 IP-Port-Local-Id TLV: 534 This TLV contains a local session identifier at the customer 535 premise, such as MAC address, interface ID, VLAN ID, PPP 536 sessions ID, VRF ID, IPv6 address/prefix, etc. Either this TLV 537 or IP-Port-Int-IP-Addr TLV must be included as part of the IP- 538 Port-Forwarding-Map Attribute. Refer to Section 3.2.11. 540 IP-Port-Ext-IPv4-Addr TLV: 542 This TLV contains an IPv4 address that is associated with the 543 external IP port number contained in the IP-Port-Ext-Port TLV. 544 This TLV may be included as part of the IP-Port-Forwarding-Map 545 Attribute. Refer to Section 3.2.3. 547 The IP-Port-Forwarding-Map attribute is associated with the following 548 identifier: Type(TBA1).Extended-Type(TBA4). [IP-Port-Int-Port 549 TLV(TBA10), IP-Port-Ext-Port TLV(TBA11), IP-Port-Type TLV(TBA5), {IP- 550 Port-Int-IPv4-Addr TLV(TBA8) | IP-Port-Int-IPv6-Addr TLV(TBA9)}, {IP- 551 Port-Ext-IPv4-Addr TLV(TBA7)}]. 553 3.2. RADIUS TLVs for IP Ports 555 3.2.1. IP-Port-Type TLV 557 This TLV (Figure 4) uses the format defined in [RFC6929]. Its Type 558 field contains a value that uniquely refers to IPFIX Element 559 transportType (TBAx1), and its Value field contains IPFIX Element 560 transportType, which indicates the type of IP transport type as 561 follows: 563 1: 565 Refer to TCP port, UDP port, and ICMP identifier as a whole. 567 2: 569 Refer to TCP port and UDP port as a whole. 571 3: 573 Refer to TCP port only. 575 4: 577 Refer to UDP port only. 579 5: 581 Refer to ICMP identifier only. 583 0 1 2 3 584 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 1 585 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 | Type | Length | transportType | 587 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 | transportType | 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 Figure 4 593 Type: 595 TBA5: This uniquely refers to IPFIX Element ID TBA0. 597 Length: 599 6. 601 transportType: 603 Integer. This field contains the data (unsigned8) of 604 transportType (TBX1) defined in IPFIX, right justified, and the 605 unused bits in this field must be set to zero. 607 3.2.2. IP-Port-Limit TLV 609 This TLV (Figure 5) uses the format defined in [RFC6929]. Its Type 610 field contains a value that uniquely refers to IPFIX Element 611 natTransportLimit (TBAx2), and its Value field contains IPFIX Element 612 natTransportLimit, which indicates the maximum number of ports of a 613 specified IP-Port-Type and associated with a given IPv4 address 614 assigned to a subscriber. 616 0 1 2 3 617 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 1 618 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 | Type | Length | natTransportLimit | 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 | natTransportLimit | 622 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 624 Figure 5 626 Type: 628 TBA6: This uniquely refers to IPFIX Element ID Limit TBD. 630 Length: 632 6. 634 natTransportLimit: 636 Integer. This field contains the data (unsigned16) of 637 natTransportLimit (TBX2) defined in IPFIX, right justified, and 638 the unused bits in this field must be set to zero. 640 3.2.3. IP-Port-Ext-IPv4-Addr TLV 642 This TLV (Figure 6) uses the format defined in[RFC6929]. Its Type 643 field contains a value that uniquely refers to IPFIX Element 644 postNATSourceIPv4Address(225), and its Value field contains IPFIX 645 Element postNATSourceIPv4Address, which is the IPv4 source address 646 after NAT operation (refer to [IPFIX]). 648 IP-Port-Ext-IPv4-Addr TLV can be included as part of the IP-Port- 649 Limit Attribute (refer to Section 3.1.1), IP-Port-Range Attribute 650 (refer to Section 3.1.2), and IP-Port-Forwarding-Map Attribute (refer 651 to Section 3.1.3). 653 0 1 2 3 654 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 1 655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 656 | Type | Length | postNATSourceIPv4Address | 657 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 | postNATSourceIPv4Address | 659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 661 Figure 6 663 Type: 665 TBA7: The type field uniquely refers to the IPFIX Element ID 225. 667 Length: 669 6 671 postNATSourceIPv4Address: 673 Integer. This field contains the data (ipv4Address) of 674 postNATSourceIPv4Address (225) defined in IPFIX. 676 3.2.4. IP-Port-Int-IPv4-Addr TLV 678 This TLV (Figure 7) uses format defined in [RFC6929]. Its Type field 679 contains a value that uniquely refers to IPFIX Element 680 sourceIPv4Address (8), and its Value field contains IPFIX Element 681 sourceIPv4Address, which is the IPv4 source address before NAT 682 operation (refer to [IPFIX]). 684 IP-Port-Int-IPv4-Addr TLV can be included as part of the IP-Port- 685 Forwarding-Map Attribute (refer to Section 3.1.3). 687 0 1 2 3 688 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 1 689 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 690 | Type | Length | sourceIPv4Address | 691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 692 | sourceIPv4Address | 693 +-+--+-+-+-+-+-+-++-+-+-+-+-+-+-+ 695 Figure 7 697 Type: 699 TBA8: The type field uniquely refers to the IPFIX Element ID 8. 701 Length: 703 6. 705 sourceIPv4Address: 707 Integer. This field contains the data (ipv4Address) of 708 sourceIPv4Address (8) defined in IPFIX. 710 3.2.5. IP-Port-Int-IPv6-Addr TLV 712 This TLV (Figure 8) uses format defined in [RFC6929]. Its Type field 713 contains a value that uniquely refers to IPFIX Element 714 sourceIPv6Address(27), and its Value field contains IPFIX Element 715 sourceIPv6Address, which is the IPv6 source address before NAT 716 operation (refer to [IPFIX]). 718 IP-Port-Int-IPv6-Addr TLV can be included as part of the IP-Port- 719 Forwarding-Map Attribute (refer to Section 3.1.3). 721 0 1 2 3 722 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 1 723 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 724 | Type | Length | sourceIPv6Address | 725 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 726 | sourceIPv6Address | 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | sourceIPv6Address | 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 | sourceIPv6Address | 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 732 | sourceIPv6Address | 733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 735 Figure 8 737 Type: 739 TBA9: The type field uniquely refers to the IPFIX Element ID 27. 741 Length: 743 18. 745 sourceIPv6Address: 747 IPv6 address (128 bits). This field contains the data 748 (ipv6Address) of sourceIPv6Address (27) defined in IPFIX. 750 3.2.6. IP-Port-Int-Port TLV 752 This TLV (Figure 9) uses format defined in [RFC6929]. Its Type field 753 contains a value that uniquely refers to IPFIX Element 754 sourceTransportPort (7), and its Value field contains IPFIX Element 755 sourceTransportPort, which is the source transport number associated 756 with an internal IPv4 or IPv6 address (refer to [IPFIX]). 758 IP-Port-Int-Port TLV is included as part of the IP-Port-Forwarding- 759 Map Attribute (refer to Section 3.1.3). 761 0 1 2 3 762 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 1 763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 764 | Type | Length | sourceTransportPort | 765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 766 | sourceTransportPort | 767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 769 Figure 9 771 Type: 773 TBA10: This uniquely refers to the IPFIX Element ID 7. 775 Length: 777 4. 779 sourceTransportPort: 781 Integer. This field contains the data (unsigned16) of 782 sourceTrasnportPort (7) defined in IPFIX, right justified, and 783 unused bits must be set to zero. 785 3.2.7. IP-Port-Ext-Port TLV 787 This TLV (Figure 10) uses format defined in [RFC6929]. Its Type 788 field contains a value that uniquely refers to IPFIX Element 789 postNAPTSourceTransportPort (227), and its Value field contains IPFIX 790 Element postNAPTSourceTransportPort, which is the transport number 791 associated with an external IPv4 address(refer to [IPFIX]). 793 IP-Port-Ext-Port TLV is included as part of the IP-Port-Forwarding- 794 Map Attribute (refer to Section 3.1.3). 796 0 1 2 3 797 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 1 798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 799 | Type | Length | postNAPTSourceTransportPort | 800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 801 | postNAPTSourceTransportPort | 802 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 804 Figure 10 806 Type: 808 TBA11: This uniquely refers to the IPFIX Element ID 227 . 810 Length: 812 6. 814 postNAPTSourceTransportPort: 816 Integer. This field contains the data (unsigned16) of 817 postNAPTSourceTrasnportPort (227) defined in IPFIX, right 818 justified, and unused bits must be set to zero. 820 3.2.8. IP-Port-Alloc TLV 822 This TLV (Figure 11) uses format defined in [RFC6929]. Its Type 823 field contains a value that uniquely refers to IPFIX Element natEvent 824 (230), and its Value field contains IPFIX Element "natEvent", which 825 is a flag to indicate an action of NAT operation (refer to [IPFIX]). 827 When the value of natEvent is "1" (Create event), it means to 828 allocate a range of transport ports; when the value is "2", it means 829 to de-allocate a range of transports ports. For the purpose of this 830 TLV, no other value is used. 832 IP-Port-Alloc TLV is included as part of the IP-Port-Range Attribute 833 (refer to Section 3.1.2). 835 0 1 2 3 836 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 1 837 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 | Type | Length | natEvent | 839 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 840 | natEvent | 841 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 Figure 11 845 Type: 847 TBA12: This uniquely refers to the IPFIX Element ID 230 . 849 Length: 851 3. 853 natEvent: 855 Integer. This field contains the data (unsigned8) of natEvent 856 (230) defined in IPFIX, right justified, and unused bits must be 857 set to zero. It indicates the allocation or deallocation of a 858 range of IP ports as follows: 860 1: 862 Allocation 864 2: 866 Deallocation 868 Reserved: 870 0. 872 3.2.9. IP-Port-Range-Start TLV 874 This TLV (Figure 12) uses format defined in [RFC6929]. Its Type 875 field contains a value that uniquely refers to IPFIX Element 876 portRangeStart (361), and its Value field contains IPFIX Element 877 portRangeStart, which is the smallest port number of a range of 878 contiguous transport ports (refer to [IPFIX]). 880 IP-Port-Range-Start TLV is included as part of the IP-Port-Range 881 Attribute (refer to Section 3.1.2). 883 0 1 2 3 884 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 1 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | Type | Length | portRangeStart | 887 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 | portRangeStart | 889 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 891 Figure 12 893 Type: 895 TBA13: This uniquely refers to the IPFIX Element ID 361. 897 TLV8-Length: 899 4. 901 portRangeStart: 903 Integer. This field contains the data (unsigned16) of (361) 904 defined in IPFIX, right justified, and unused bits must be set to 905 zero. 907 3.2.10. IP-Port-Range-End TLV 909 This TLV (Figure 13) uses format defined in [RFC6929]. Its Type 910 field contains a value that uniquely refers to IPFIX Element 911 portRangeEnd (362), and its Value field contains IPFIX Element 912 portRangeEnd, which is the largest port number of a range of 913 contiguous transport ports (refer to [IPFIX]). 915 IP-Port-Range-End TLV is included as part of the IP-Port-Range 916 Attribute (refer to Section 3.1.2). 918 0 1 2 3 919 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 1 920 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 921 | Type | Length | portRangeEnd | 922 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 923 | portRangeEnd | 924 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 926 Figure 13 928 Type: 930 TBA14: This uniquely refers to IPFIC Element ID 362. 932 Length: 934 4. The Length field for IP-Port-Range-End TLV. 936 portRangeEnd: 938 Integer. This field contains the data (unsigned16) of (362) 939 defined in IPFIX, right justified, and unused bits must be set to 940 zero. 942 3.2.11. IP-Port-Local-Id TLV 944 This TLV (Figure 14) uses format defined in [RFC6929]. Its Type 945 field contains a value that uniquely refers to IPFIX Element localID 946 (TBAx3), and its Value field contains IPFIX Element localID, which is 947 a local significant identifier as explained below. 949 In some CGN deployment scenarios such as DS-Extra-Lite [RFC6619] and 950 Lightweight 4over6 [I-D.ietf-softwire-lw4over6], parameters at a 951 customer premise such as MAC address, interface ID, VLAN ID, PPP 952 session ID, IPv6 prefix, VRF ID, etc., may also be required to pass 953 to the RADIUS server as part of the accounting record. 955 IP-Port-Local-Id TLV can be included as part of the IP-Port-Range 956 Attribute (refer to Section 3.1.2) and IP-Port-Forwarding-Map 957 Attribute (refer to Section 3.1.3). 959 0 1 2 3 960 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 1 961 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 962 | Type | Length | localID .... 963 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 965 Figure 14 967 Type: 969 TBA15: This uniquely refers to IPFIX Element ID TBD. 971 Length: 973 Variable number of bytes. 975 localID: 977 string. This field contains the data (string) of (TBAX3) defined 978 in IPFIX. This is a local session identifier at the customer 979 premise, such as MAC address, interface ID, VLAN ID, PPP sessions 980 ID, VRF ID, IPv6 address/prefix, etc. 982 4. Applications, Use Cases and Examples 984 This section describes some applications and use cases to illustrate 985 the use of the attributes proposed in this document. 987 4.1. Managing CGN Port Behavior using RADIUS 989 In a broadband network, customer information is usually stored on a 990 RADIUS server, and the BNG hosts the NAS. The communication between 991 the NAS and the RADIUS server is triggered by a subscriber when the 992 user signs in to the Internet service, where either PPP or DHCP/ 993 DHCPv6 is used. When a user signs in, the NAS sends a RADIUS Access- 994 Request message to the RADIUS server. The RADIUS server validates 995 the request, and if the validation succeeds, it in turn sends back a 996 RADIUS Access-Accept message. The Access-Accept message carries 997 configuration information specific to that user, back to the NAS, 998 where some of the information would pass on to the requesting user 999 via PPP or DHCP/DHCPv6. 1001 A CGN function in a broadband network would most likely reside on a 1002 BNG. In that case, parameters for CGN port/identifier mapping 1003 behavior for users can be configured on the RADIUS server. When a 1004 user signs in to the Internet service, the associated parameters can 1005 be conveyed to the NAS, and proper configuration is accomplished on 1006 the CGN device for that user. 1008 Also, CGN operation status such as CGN port/identifier allocation and 1009 de-allocation for a specific user on the BNG can also be transmitted 1010 back to the RADIUS server for accounting purpose using the RADIUS 1011 protocol. 1013 RADIUS protocol has already been widely deployed in broadband 1014 networks to manage BNG, thus the functionality described in this 1015 specification introduces little overhead to the existing network 1016 operation. 1018 In the following sub-sections, we describe how to manage CGN behavior 1019 using RADIUS protocol, with required RADIUS extensions proposed in 1020 Section 3. 1022 4.1.1. Configure IP Port Limit for a User 1024 In the face of IPv4 address shortage, there are currently proposals 1025 to multiplex multiple subscribers' connections over a smaller number 1026 of shared IPv4 addresses, such as Carrier Grade NAT [RFC6888], Dual- 1027 Stack Lite [RFC6333], NAT64 [RFC6146], etc. As a result, a single 1028 IPv4 public address may be shared by hundreds or even thousands of 1029 subscribers. As indicated in [RFC6269], it is therefore necessary to 1030 impose limits on the total number of ports available to an individual 1031 subscriber to ensure that the shared resource, i.e., the IPv4 address 1032 remains available in some capacity to all the subscribers using it, 1033 and port limiting is also documented in [RFC6888] as a requirement. 1035 The IP port limit imposed to a specific subscriber may be on the 1036 total number of TCP and UDP ports plus the number of ICMP 1037 identifiers, or with other granularities as defined in Section 3.1.1. 1039 The per-subscriber based IP port limit is configured on a RADIUS 1040 server, along with other user information such as credentials. The 1041 value of these IP port limit is based on service agreement and its 1042 specification is out of the scope of this document. 1044 When a subscriber signs in to the Internet service successfully, the 1045 IP port limit for the subscriber is passed to the BNG based NAS, 1046 where CGN also locates, using a new RADIUS attribute called IP-Port- 1047 Limit (defined in Section 3.1.1), along with other configuration 1048 parameters. While some parameters are passed to the subscriber, the 1049 IP port limit is recorded on the CGN device for imposing the usage of 1050 TCP/UDP ports and ICMP identifiers for that subscriber. 1052 Figure 15 illustrates how RADIUS protocol is used to configure the 1053 maximum number of TCP/UDP ports for a given subscriber on a NAT44 1054 device. 1056 User NAT44/NAS AAA 1057 | BNG Server 1058 | | | 1059 | | | 1060 |----Service Request------>| | 1061 | | | 1062 | |-----Access-Request -------->| 1063 | | | 1064 | |<----Access-Accept-----------| 1065 | | (IP-Port-Limit) | 1066 | | (for TCP/UDP ports) | 1067 |<---Service Granted ------| | 1068 | (other parameters) | | 1069 | | | 1070 | (NAT44 external port | 1071 | allocation and | 1072 | IPv4 address assignment) | 1073 | | | 1075 Figure 15: RADIUS Message Flow for Configuring NAT44 Port Limit 1077 The IP port limit created on a CGN device for a specific user using 1078 RADIUS extension may be changed using RADIUS CoA message [RFC5176] 1079 that carries the same RADIUS attribute. The CoA message may be sent 1080 from the RADIUS server directly to the NAS, which once accepts and 1081 sends back a RADIUS CoA ACK message, the new IP port limit replaces 1082 the previous one. 1084 Figure 16 illustrates how RADIUS protocol is used to increase the 1085 TCP/UDP port limit from 1024 to 2048 on a NAT44 device for a specific 1086 user. 1088 User NAT/NAS AAA 1089 | BNG Server 1090 | | | 1091 | TCP/UDP Port Limit (1024) | 1092 | | | 1093 | |<---------CoA Request----------| 1094 | | (IP-Port-Limit) | 1095 | | (for TCP/UDP ports) | 1096 | | | 1097 | TCP/UDP Port Limit (2048) | 1098 | | | 1099 | |---------CoA Response--------->| 1100 | | | 1102 Figure 16: RADIUS Message Flow for changing a user's NAT44 port limit 1104 4.1.2. Report IP Port Allocation/De-allocation 1106 Upon obtaining the IP port limit for a subscriber, the CGN device 1107 needs to allocate a TCP/UDP port or an ICMP identifiers for the 1108 subscriber when receiving a new IP flow sent from that subscriber. 1110 As one practice, a CGN may allocate a bulk of TCP/UDP ports or ICMP 1111 identifiers once at a time for a specific user, instead of one port/ 1112 identifier at a time, and within each port bulk, the ports/ 1113 identifiers may be randomly distributed or in consecutive fashion. 1114 When a CGN device allocates bulk of TCP/UDP ports and ICMP 1115 identifiers, the information can be easily conveyed to the RADIUS 1116 server by a new RADIUS attribute called the IP-Port-Range (defined in 1117 Section 3.1.2). The CGN device may allocate one or more TCP/UDP port 1118 ranges or ICMP identifier ranges, or generally called IP port ranges, 1119 where each range contains a set of numbers representing TCP/UDP ports 1120 or ICMP identifiers, and the total number of ports/identifiers must 1121 be less or equal to the associated IP port limit imposed for that 1122 subscriber. A CGN device may choose to allocate a small port range, 1123 and allocate more at a later time as needed; such practice is good 1124 because its randomization in nature. 1126 At the same time, the CGN device also needs to decide the shared IPv4 1127 address for that subscriber. The shared IPv4 address and the pre- 1128 allocated IP port range are both passed to the RADIUS server. 1130 When a subscriber initiates an IP flow, the CGN device randomly 1131 selects a TCP/UDP port or ICMP identifier from the associated and 1132 pre-allocated IP port range for that subscriber to replace the 1133 original source TCP/UDP port or ICMP identifier, along with the 1134 replacement of the source IP address by the shared IPv4 address. 1136 A CGN device may decide to "free" a previously assigned set of TCP/ 1137 UDP ports or ICMP identifiers that have been allocated for a specific 1138 subscriber but not currently in use, and with that, the CGN device 1139 must send the information of the de-allocated IP port range along 1140 with the shared IPv4 address to the RADIUS server. 1142 Figure 17 illustrates how RADIUS protocol is used to report a set of 1143 ports allocated and de-allocated, respectively, by a NAT44 device for 1144 a specific user to the RADIUS server. 1146 Host NAT44/NAS AAA 1147 | BNG Server 1148 | | | 1149 | | | 1150 |----Service Request------>| | 1151 | | | 1152 | |-----Access-Request -------->| 1153 | | | 1154 | |<----Access-Accept-----------| 1155 |<---Service Granted ------| | 1156 | (other parameters) | | 1157 ... ... ... 1158 | | | 1159 | | | 1160 | (NAT44 decides to allocate | 1161 | a TCP/UDP port range for the user) | 1162 | | | 1163 | |-----Accounting-Request----->| 1164 | | (IP-Port-Range | 1165 | | for allocation) | 1166 ... ... ... 1167 | | | 1168 | (NAT44 decides to de-allocate | 1169 | a TCP/UDP port range for the user) | 1170 | | | 1171 | |-----Accounting-Request----->| 1172 | | (IP-Port-Range | 1173 | | for de-allocation) | 1174 | | | 1176 Figure 17: RADIUS Message Flow for reporting NAT44 allocation/de- 1177 allocation of a port set 1179 4.1.3. Configure Forwarding Port Mapping 1181 In most scenarios, the port mapping on a NAT device is dynamically 1182 created when the IP packets of an IP connection initiated by a user 1183 arrives. For some applications, the port mapping needs to be pre- 1184 defined allowing IP packets of applications from outside a CGN device 1185 to pass through and "port forwarded" to the correct user located 1186 behind the CGN device. 1188 Port Control Protocol [RFC6887], provides a mechanism to create a 1189 mapping from an external IP address and port to an internal IP 1190 address and port on a CGN device just to achieve the "port 1191 forwarding" purpose. PCP is a server-client protocol capable of 1192 creating or deleting a mapping along with a rich set of features on a 1193 CGN device in dynamic fashion. In some deployment, all users need is 1194 a few, typically just one pre-configured port mapping for 1195 applications such as web cam at home, and the lifetime of such a port 1196 mapping remains valid throughout the duration of the customer's 1197 Internet service connection time. In such an environment, it is 1198 possible to statically configure a port mapping on the RADIUS server 1199 for a user and let the RADIUS protocol to propagate the information 1200 to the associated CGN device. 1202 Figure 18 illustrates how RADIUS protocol is used to configure a 1203 forwarding port mapping on a NAT44 device by using RADIUS protocol. 1205 Host NAT/NAS AAA 1206 | BNG Server 1207 | | | 1208 |----Service Request------>| | 1209 | | | 1210 | |---------Access-Request------->| 1211 | | | 1212 | |<--------Access-Accept---------| 1213 | | (IP-Port-Forwarding-Map) | 1214 |<---Service Granted ------| | 1215 | (other parameters) | | 1216 | | | 1217 | (Create a port mapping | 1218 | for the user, and | 1219 | associate it with the | 1220 | internal IP address | 1221 | and external IP address) | 1222 | | | 1223 | | | 1224 | |------Accounting-Request------>| 1225 | | (IP-Port-Forwarding-Map) | 1227 Figure 18: RADIUS Message Flow for configuring a forwarding port 1228 mapping 1230 A port forwarding mapping that is created on a CGN device using 1231 RADIUS extension as described above may also be changed using RADIUS 1232 CoA message [RFC5176] that carries the same RADIUS associate. The 1233 CoA message may be sent from the RADIUS server directly to the NAS, 1234 which once accepts and sends back a RADIUS CoA ACK message, the new 1235 port forwarding mapping then replaces the previous one. 1237 Figure 19 illustrates how RADIUS protocol is used to change an 1238 existing port mapping from (a:X) to (a:Y), where "a" is an internal 1239 port, and "X" and "Y" are external ports, respectively, for a 1240 specific user with a specific IP address 1241 Host NAT/NAS AAA 1242 | BNG Server 1243 | | | 1244 | Internal IP Address | 1245 | Port Map (a:X) | 1246 | | | 1247 | |<---------CoA Request----------| 1248 | | (IP-Port-Forwarding-Map) | 1249 | | | 1250 | Internal IP Address | 1251 | Port Map (a:Y) | 1252 | | | 1253 | |---------CoA Response--------->| 1254 | | (IP-Port-Forwarding-Map) | 1256 Figure 19: RADIUS Message Flow for changing a user's forwarding port 1257 mapping 1259 4.1.4. An Example 1261 An Internet Service Provider (ISP) assigns TCP/UDP 500 ports for the 1262 subscriber Joe. This number is the limit that can be used for TCP/UDP 1263 ports on a NAT44 device for Joe, and is configured on a RADIUS 1264 server. Also, Joe asks for a pre-defined port forwarding mapping on 1265 the NAT44 device for his web cam applications (external port 5000 1266 maps to internal port 80). 1268 When Joe successfully connects to the Internet service, the RADIUS 1269 server conveys the TCP/UDP port limit (1000) and the forwarding port 1270 mapping (external port 5000 to internal port 80) to the NAT44 device, 1271 using IP-Port-Limit attribute and IP-Port-Forwarding-Map attribute, 1272 respectively, carried by an Access-Accept message to the BNG where 1273 NAS and CGN co-located. 1275 Upon receiving the first outbound IP packet sent from Joe's laptop, 1276 the NAT44 device decides to allocate a small port pool that contains 1277 40 consecutive ports, from 3500 to 3540, inclusively, and also assign 1278 a shared IPv4 address 192.0.2.15, for Joe. The NAT44 device also 1279 randomly selects one port from the allocated range (say 3519) and use 1280 that port to replace the original source port in outbound IP packets. 1282 For accounting purpose, the NAT44 device passes this port range 1283 (3500-3540) and the shared IPv4 address 192.0.2.15 together to the 1284 RADIUS server using IP-Port-Range attribute carried by an Accounting- 1285 Request message. 1287 When Joe works on more applications with more outbound IP sessions 1288 and the port pool (3500-3540) is close to exhaust, the NAT44 device 1289 allocates a second port pool (8500-8800) in a similar fashion, and 1290 also passes the new port range (8500-8800) and IPv4 address 1291 192.0.2.15 together to the RADIUS server using IP-Port-Range 1292 attribute carried by an Accounting-Request message. Note when the 1293 CGN allocates more ports, it needs to assure that the total number of 1294 ports allocated for Joe is within the limit. 1296 Joe decides to upgrade his service agreement with more TCP/UDP ports 1297 allowed (up to 1000 ports). The ISP updates the information in Joe's 1298 profile on the RADIUS server, which then sends a CoA-Request message 1299 that carries the IP-Port-Limit attribute with 1000 ports to the NAT44 1300 device; the NAT44 device in turn sends back a CoA-ACK message. With 1301 that, Joe enjoys more available TCP/UDP ports for his applications. 1303 When Joe travels, most of the IP sessions are closed with their 1304 associated TCP/UDP ports released on the NAT44 device, which then 1305 sends the relevant information back to the RADIUS server using IP- 1306 Port-Range attribute carried by Accounting-Request message. 1308 Throughout Joe's connection with his ISP Internet service, 1309 applications can communicate with his web cam at home from external 1310 realm directly traversing the pre-configured mapping on the CGN 1311 device. 1313 When Joe disconnects from his Internet service, the CGN device will 1314 de-allocate all TCP/UDP ports as well as the port-forwarding mapping, 1315 and send the relevant information to the RADIUS server. 1317 4.2. Report Assigned Port Set for a Visiting UE 1319 Figure 20 illustrates an example of the flow exchange which occurs 1320 when a visiting UE connects to a CPE offering WLAN service. 1322 For identification purposes (see [RFC6967]), once the CPE assigns a 1323 port set, it issues a RADIUS message to report the assigned port set. 1325 UE CPE NAS AAA 1326 | BNG Server 1327 | | | 1328 | | | 1329 |----Service Request------>| | 1330 | | | 1331 | |-----Access-Request -------->| 1332 | | | 1333 | |<----Access-Accept-----------| 1334 |<---Service Granted ------| | 1335 | (other parameters) | | 1336 ... | ... ... 1337 |<---IP@----| | | 1338 | | | | 1339 | (CPE assigns a TCP/UDP port | 1340 | range for this visiting UE) | 1341 | | | 1342 | |--Accounting-Request-...------------------->| 1343 | | (IP-Port-Range | 1344 | | for allocation) | 1345 ... | ... ... 1346 | | | | 1347 | | | | 1348 | (CPE withdraws a TCP/UDP port | 1349 | range for a visiting UE) | 1350 | | | 1351 | |--Accounting-Request-...------------------->| 1352 | | (IP-Port-Range | 1353 | | for de-allocation) | 1354 | | | 1356 Figure 20: RADIUS Message Flow for reporting CPE allocation/de- 1357 allocation of a port set to a visiting UE 1359 5. Table of Attributes 1361 This document proposes three new RADIUS attributes and their formats 1362 are as follows: 1364 o IP-Port-Limit: TBA1.TBA2.[TBA6, TBA5, {TBA7}] 1366 o IP-Port-Range: TBA1.TBA3.[TBA12, TBA5, {TBA13, TBA14}, {TBA7}, 1367 {TBA15}]. 1369 o IP-Port-Forwarding-Map: TBA1.TBA4.[TBA10, TBA11, TBA5, {TBA8 | 1370 TBA9}, {TBA7}] 1372 The following table provides a guide as what type of RADIUS packets 1373 that may contain these attributes, and in what quantity. 1375 Request Accept Reject Challenge Acct. # Attribute 1376 Request 1377 0+ 0+ 0 0 0+ TBA IP-Port-Limit 1378 0 0 0 0 0+ TBA IP-Port-Range 1379 0+ 0+ 0 0 0+ TBA IP-Port-Forwarding-Map 1381 The following table defines the meaning of the above table entries. 1383 0 This attribute MUST NOT be present in packet. 1384 0+ Zero or more instances of this attribute MAY be present in packet. 1386 6. Security Considerations 1388 This document does not introduce any security issue than what has 1389 been identified in [RFC2865]. 1391 7. IANA Considerations 1393 This document requires new code point assignments for both IPFIX 1394 Elements and RADIUS attributes as explained in the following 1395 sections. 1397 7.1. IANA Considerations on New IPFIX Elements 1399 The following are code point assignments for new IPFIX Elements as 1400 requested by this document: 1402 o transportType (refer to Section 3.2.1): The identifier of this 1403 IPFIX Element is TBAx1. The data type of this IPFIX Element is 1404 unsigned8, and the Element's value indicates TCP/UDP ports and 1405 ICMP Identifiers (1), TCP/UDP ports (2), TCP ports (3), UDP ports 1406 (4) or ICMP identifiers (5). 1408 o natTransportLimit (refer to Section 3.2.2): The identifier of this 1409 IPFIX Element is TBAx2. The data type of this IPFIX Element is 1410 unsigned16, and the Element's value is the max number of IP 1411 transport ports to be assigned to an end user associated with one 1412 or more IPv4 addresses. 1414 o localID (refer to Section 3.2.11): The identifier of this IPFIX 1415 Element is TBAx3. The data type of this IPFIX Element is string, 1416 and the Element's value is an IPv4 or IPv6 address, a MAC address, 1417 a VLAN ID, etc. 1419 7.2. IANA Considerations on New RADIUS Attributes 1421 The following are new code point assignment for RADIUS extensions as 1422 requested by this document: 1424 o TBA1: This value is allocated from Radius Extended-Type space. 1425 Refer to Section 3.1.1, Section 3.1.2, and Section 3.1.3. 1427 o TBA2: This is allocated from TBA1, so TBA1.TBA2 identifies a new 1428 RADIUS attribute IP-Port-Limit. Refer to Section 3.1.1. 1430 o TBA3: This is allocated from TBA1, so TBA1.TBA3 indentifies a new 1431 RADIUS attribute IP-Port-Range. Refer to Section 3.1.2. 1433 o TBA4: This is allocated from TBA1, so TBA1.TBA4 indentifies a new 1434 RADISU attribute IP-Port-Forwarding-Map. Refer to Section 3.1.3. 1436 o TBA5 (refer to Section 3.2.1): This is for the Type field of IP- 1437 Port-Type TLV. It should be allocated as TLV data type. The 1438 Value filed of this TLV contains the data of IPFIX Element 1439 transportType (TBAx1). 1441 o TBA6 (refer to Section 3.2.2): This is for the Type field of IP- 1442 Port-Limit TLV. It should be allocated as TLV data type. The 1443 Value field of this TLV contains the data of IPFIX Element 1444 natTransportLimit(TBAx2). 1446 o TBA7 (refer to Section 3.2.3): This is for the Type field of IP- 1447 Port-Ext-IPv4-Addr TLV. It should be allocated as TLV data type. 1448 The Value field of this TLV contains the data of IPFIX Element 1449 postNATSourceIPv4Address(225). 1451 o TBA8 (refer to Section 3.2.4): This is for the Type field of IP- 1452 Port-Int-IPv4-Addr TLV. It should be allocated as TLV data type. 1453 The Value field of this TLV contains the data of IPFIX Element 1454 sourceIPv4Address(8). 1456 o TBA9 (refer to Section 3.2.5): This is for the Type field of IP- 1457 Port-Int-IPv6-Addr TLV. It should be allocated as TLV data type. 1458 The Value field of this TLV contains the data of IPFIX Element 1459 sourceIPv6Address(27). 1461 o TBA10 (refer to Section 3.2.6): This is for the Type field of IP- 1462 Port-Int-Port TLV. It should be allocated as TLV data type. The 1463 Value field of this TLV containss the data of IPFIX Element 1464 sourceTransportPort(7). 1466 o TBA11 (refer to Section 3.2.7): This is for the Type field of IP- 1467 Port-Ext-port TLV. It should be allocated as TLV data type. The 1468 Value field of this TLV contains the data of IPFIX Element 1469 postNAPTSourceTransportPort(227). 1471 o TBA12 (refer to Section 3.2.8): This is for the Type field of IP- 1472 Port-Alloc TLV. It should be allocated as TLV data type. The 1473 Value field of this TLV contains the data of IPFIX Element 1474 natEvent(230). 1476 o TBA13 (refer to Section 3.2.9): This is for the Type field of IP- 1477 Port-Range-Start TLV. It should be allocated as TLV data type. 1478 The Value field of this TLV contains the data of IPFIX Element 1479 portRangeStart(361). 1481 o TBA14 (refer to Section 3.2.10): This is for the Type field of IP- 1482 Port-Range-End TLV. It should be allocated as TLV data type. The 1483 Value field of this TLV contains the data of IPFIX Element 1484 portRangeEnd(362). 1486 o TBA15 (refer to Section 3.2.11): This is for the Type field of IP- 1487 Port-Local-Id TLV. It should be allocated as TLV data type. The 1488 Value field of this TLV contains the data of IPFIX Element 1489 localID(TBAx3). 1491 8. Acknowledgements 1493 Many thanks to Dan Wing, Roberta Maglione, Daniel Derksen, David 1494 Thaler, Alan Dekok, Lionel Morand, and Peter Deacon for their useful 1495 comments and suggestions. 1497 9. References 1499 9.1. Normative References 1501 [IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities", 1502 . 1504 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 1505 E. Lear, "Address Allocation for Private Internets", BCP 1506 5, RFC 1918, February 1996. 1508 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1509 Requirement Levels", BCP 14, RFC 2119, March 1997. 1511 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, 1512 June 1999. 1514 [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, 1515 "Remote Authentication Dial In User Service (RADIUS)", RFC 1516 2865, June 2000. 1518 [RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. 1519 Aboba, "Dynamic Authorization Extensions to Remote 1520 Authentication Dial In User Service (RADIUS)", RFC 5176, 1521 January 2008. 1523 [RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User 1524 Service (RADIUS) Protocol Extensions", RFC 6929, April 1525 2013. 1527 [RFC7012] Claise, B. and B. Trammell, "Information Model for IP Flow 1528 Information Export (IPFIX)", RFC 7012, September 2013. 1530 [TR-146] Broadband Forum, "TR-146: Subscriber Sessions", 1531 . 1534 9.2. Informative References 1536 [I-D.gundavelli-v6ops-community-wifi-svcs] 1537 Gundavelli, S., Grayson, M., Seite, P., and Y. Lee, 1538 "Service Provider Wi-Fi Services Over Residential 1539 Architectures", draft-gundavelli-v6ops-community-wifi- 1540 svcs-06 (work in progress), April 2013. 1542 [I-D.ietf-softwire-lw4over6] 1543 Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and 1544 I. Farrer, "Lightweight 4over6: An Extension to the DS- 1545 Lite Architecture", draft-ietf-softwire-lw4over6-13 (work 1546 in progress), November 2014. 1548 [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network 1549 Address Translator (Traditional NAT)", RFC 3022, January 1550 2001. 1552 [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful 1553 NAT64: Network Address and Protocol Translation from IPv6 1554 Clients to IPv4 Servers", RFC 6146, April 2011. 1556 [RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P. 1557 Roberts, "Issues with IP Address Sharing", RFC 6269, June 1558 2011. 1560 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 1561 Stack Lite Broadband Deployments Following IPv4 1562 Exhaustion", RFC 6333, August 2011. 1564 [RFC6619] Arkko, J., Eggert, L., and M. Townsley, "Scalable 1565 Operation of Address Translators with Per-Interface 1566 Bindings", RFC 6619, June 2012. 1568 [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. 1569 Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 1570 2013. 1572 [RFC6888] Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A., 1573 and H. Ashida, "Common Requirements for Carrier-Grade NATs 1574 (CGNs)", BCP 127, RFC 6888, April 2013. 1576 [RFC6967] Boucadair, M., Touch, J., Levis, P., and R. Penno, 1577 "Analysis of Potential Solutions for Revealing a Host 1578 Identifier (HOST_ID) in Shared Address Deployments", RFC 1579 6967, June 2013. 1581 Authors' Addresses 1583 Dean Cheng 1584 Huawei 1585 2330 Central Expressway 1586 Santa Clara, California 95050 1587 USA 1589 Email: dean.cheng@huawei.com 1591 Jouni Korhonen 1592 Broadcom Corporation 1593 3151 Zanker Road 1594 San Jose 95134 1595 USA 1597 Email: jouni.nospam@gmail.com 1599 Mohamed Boucadair 1600 France Telecom 1601 Rennes 1602 France 1604 Email: mohamed.boucadair@orange.com 1605 Senthil Sivakumar 1606 Cisco Systems 1607 7100-8 Kit Creek Road 1608 Research Triangle Park, North Carolina 1609 USA 1611 Email: ssenthil@cisco.com