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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Franke 3 Internet-Draft NetDEF 4 Intended status: Standards Track October 19, 2015 5 Expires: April 21, 2016 7 IS-IS over IPv6 8 draft-franke-isis-over-ipv6-01 10 Abstract 12 In this draft, a method to transmit IS-IS PDUs as IPv6 packets is 13 described. While the default encapsulation of IS-IS is specified 14 directly on top of the link-layer, making it necessary for IS-IS to 15 be specified for each link-layer it should be used on, the proposed 16 method allows for IS-IS to run on any link-layers supporting IPv6. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on April 21, 2016. 35 Copyright Notice 37 Copyright (c) 2015 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 54 2. Transmitting IS-IS PDUs over IPv6 . . . . . . . . . . . . . . 2 55 2.1. Addressing . . . . . . . . . . . . . . . . . . . . . . . 2 56 2.2. IPv6 header . . . . . . . . . . . . . . . . . . . . . . . 3 57 2.3. Packet format . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Considerations for using IS-IS over IPv6 . . . . . . . . . . 3 59 3.1. SNPA . . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 3.2. MTU . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3.3. Interoperability . . . . . . . . . . . . . . . . . . . . 4 62 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 64 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 65 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 67 7.2. Informative References . . . . . . . . . . . . . . . . . 5 68 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 70 1. Introduction 72 The original specification of IS-IS [ISO.10589.2002] defines that 73 PDUs are transmitted directly on the link-layer. With this design 74 comes the problem that specification work is required each time a new 75 link-layer should be supported by IS-IS. By transmitting IS-IS PDUs 76 as IPv6 packets, this specification work can be avoided and any link- 77 layer supporting IPv6 can be used. Among other things, this allows 78 to route IPv6 with IS-IS [RFC5308] on any link supporting IPv6. 80 This specification does not make changes to the general operation of 81 IS-IS and any existing mechanisms should be kept as-is. The only 82 change made by this draft is the format of IS-IS PDUs on the wire. 84 1.1. Requirements Language 86 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 87 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 88 document are to be interpreted as described in RFC 2119 [RFC2119]. 90 2. Transmitting IS-IS PDUs over IPv6 92 2.1. Addressing 94 Link-local IPv6 addresses are used to transmit and receive IS-IS 95 PDUs. Routers SHALL set the source address of transmitted PDUs to 96 the link-local address of the outgoing interface. 98 IPv6 link-local multicast is used as destination for the packets. 99 The PDUs that would be sent to ALL-L1-IS when sending them directly 100 on top of the link-layer MUST be sent to the IPv6 multicast group 101 instead. Respectively, PDUs that would be sent to ALL-L2-IS 102 MUST be sent to the multicast group . 104 2.2. IPv6 header 106 The packets SHOULD be transmitted with type of service set to 107 Internetwork control. 109 2.3. Packet format 111 To transmit IS-IS PDUs over IPv6, they are encapsulated as IPv6 112 payload without any transport layer protocol. For that purpose, 113 protocol number 124 is used. That number was assigned by IANA for 114 IS-IS over IPv4. [I-D.ietf-isis-wg-over-ip] The PDUs are transmitted 115 as IPv6 payload starting at the NLPI. 117 3. Considerations for using IS-IS over IPv6 119 3.1. SNPA 121 Using the ethernet MAC address as SNPA on LAN links is not practical 122 for this application since the goal of this extension is to become 123 independent from specific link-layer properties. 125 Therefore, treat the whole 16 byte of the IPv6 address as SNPA. 126 Since the SNPA is only used internally to each router and not put 127 into any IS-IS PDUs, no protocol datastructures need to be modified 128 for this, but implemenations need to deal with this new SNPA length 129 internally. 131 3.2. MTU 133 Hello PDUs that are subject to padding SHALL be padded so that the 134 total IPv6 packet size matches the MTU of the link they are 135 transmitted over. Fragmentation SHALL NOT be used on hellos, and a 136 system receiving an IPv6 encapsulated SHALL verify that the hello has 137 not been subject to fragmentation. 139 Other transmitted PDUs MAY be fragmented to allow the transport of 140 LSPs that result in larger packets than the IPv6 MTU. 142 3.3. Interoperability 144 IS-IS implementations supporting IS-IS over IPv6 SHOULD provide a 145 method that allows to choose between [ISO.10589.2002] and IS-IS over 146 IPv6 encapsulation for each interface. Implementations MUST NOT 147 transmit or process ISO 10589:2002 PDUs on interfaces running in IS- 148 IS over IPv6 mode and they MUST NOT transmit or process IS-IS over 149 IPv6 PDUs on interfaces running in ISO 10589:2002 mode. 151 4. Acknowledgements 153 There has been previous work to specify operation of IS-IS over IPv4 154 [I-D.ietf-isis-wg-over-ip] which has been used as a reference for 155 this work. 157 5. IANA Considerations 159 For this protocol, IANA should assign two IPv6 multicast group IDs 160 and in the IPv6 Multicast Address Space Registry. 161 [RFC3307] Also, IANA should change the name of protocol 124 in the 162 Internet Protocol Number registry [RFC5237] from "ISIS over IPv4" to 163 "ISIS". 165 6. Security Considerations 167 Routers implementing this encapsulation of IS-IS over IPv6 can be 168 susceptible to receiving and processing IS-IS over IPv6 packets that 169 have not been originated by a router that is on-link. For example, 170 someone with malicious intent could send IS-IS over IPv6 packets to a 171 global unicast address of a router via multiple hops. 173 For this reason, routers implementing IS-IS over IPv6 need to verify 174 that the origin of each received IS-IS over IPv6 packet is indeed on- 175 link. 177 To do this, routers implementing IS-IS over IPv6 SHALL implement 178 generalized TTL security as described in [RFC5082]. Since ttl 179 security is mandatory for IS-IS over IPv6, any packet received with a 180 TTL differing from 255 can be classified as "Dangerous" and SHALL be 181 dropped. 183 7. References 185 7.1. Normative References 187 [ISO.10589.2002] 188 International Organization for Standardization, 189 "Intermediate system to intermediate system intra-domain- 190 routing routine information exchange protocol for use in 191 conjunction with the protocol for providing the 192 connectionless-mode Network Service (ISO 8473)", ISO 193 Standard 10589, 2002. 195 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 196 Requirement Levels", BCP 14, RFC 2119, March 1997. 198 [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C. 199 Pignataro, "The Generalized TTL Security Mechanism 200 (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007, 201 . 203 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October 204 2008. 206 7.2. Informative References 208 [I-D.ietf-isis-wg-over-ip] 209 Przygienda, T., Patel, A., and A. Bansal, "IS-IS over 210 IPv4", draft-ietf-isis-wg-over-ip-02 (work in progress), 211 October 1999. 213 [RFC3307] Haberman, B., "Allocation Guidelines for IPv6 Multicast 214 Addresses", RFC 3307, August 2002. 216 [RFC5237] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for 217 the Protocol Field", BCP 37, RFC 5237, DOI 10.17487/ 218 RFC5237, February 2008, 219 . 221 Author's Address 223 Christian Franke 224 NetDEF 225 Leipzig 226 DE 228 Email: chris@opensourcerouting.org