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Osborne 3 Internet-Draft Cisco 4 Intended status: Experimental February 13, 2013 5 Expires: August 17, 2013 7 Extended Administrative Groups in MPLS-TE 8 draft-osborne-mpls-extended-admin-groups-00 10 Abstract 12 This document provides additional administrative groups (sometimes 13 referred to as "link colors") to the IGP extensions for MPLS-TE. 15 Requirements Language 17 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 18 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 19 document are to be interpreted as described in RFC 2119 [RFC2119]. 21 Status of this Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on August 17, 2013. 38 Copyright Notice 40 Copyright (c) 2013 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 2. Extended Administrative Groups sub-TLV . . . . . . . . . . . . 3 57 2.1. Packet Format . . . . . . . . . . . . . . . . . . . . . . . 3 58 2.2. Admin group numbering . . . . . . . . . . . . . . . . . . . 4 59 2.3. Backward compatability . . . . . . . . . . . . . . . . . . 4 60 2.3.1. AG and EAG coexistence . . . . . . . . . . . . . . . . 4 61 2.3.2. Desire for unadvertised EAG bits . . . . . . . . . . . 4 62 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 63 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 64 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 65 6. Normative References . . . . . . . . . . . . . . . . . . . . . 5 66 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 1. Introduction 70 MPLS-TE advertises 32 administrative groups (commonly referred to as 71 "colors" or "link colors") using the Administrative Group sub-TLV of 72 the Link TLV. This is defined for OSPF [RFC3630]and ISIS [RFC5305]. 74 This document adds a sub-TLV to the IGP TE extensions, "Extended 75 Administrative Group". It 77 2. Extended Administrative Groups sub-TLV 79 The Extended Administrative Groups sub-TLV is used in addition to the 80 Administrative Groups when a device wishes to advertise more than 32 81 colors for a link. The EAG sub-TLV is optional. 83 This document uses the term 'colors' as a shorthand to refer to 84 particular bits with an AG or EAG. The examples in this document use 85 'red' to represent the least significant bit in the AG (red == 0x1), 86 'blue' to represent the second bit (blue == 0x2). To say that a link 87 has a given color or that the specified color is set on the link is 88 to say that the corresponding bit or bits in the link's AG are set to 89 1. 91 2.1. Packet Format 93 The format of the Extended Administrative Groups sub-TLV is: 95 0 1 2 3 96 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 97 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 98 | Type: Extended Admin Group | Length: Variable | 99 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 100 | Value: Extended Admin Group Value | 101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 102 | ........... | 103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 104 | Value: Extend Admin Group Value | 105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 107 The Length is the size of the Extended Admin Group (EAG) value in 108 octets. The EAG may be of any length, but must be a multiple of 4 109 octets. 111 2.2. Admin group numbering 113 By convention, the existing Administrative Group TLVs are numbered 0 114 (LSB) to 31 (MSB). The EAG values pick up where this numbering 115 scheme leaves off. The LSB in the EAG is 32. If the EAG is 4 bytes 116 in length, the MSB is 63. If the EAG is 8 bytes in length, the MSB 117 is 95. 119 2.3. Backward compatability 121 There are two things to consider for backward compatibility with 122 existing AG implementations - how do AG and EAG coexist, and what 123 happens if a node has matching criteria for unadvertised EAG bits? 125 2.3.1. AG and EAG coexistence 127 If a node advertises the EAG sub-TLV it MUST also advertise the 128 existing Administrative Group (AG) sub-TLV defined in RFCs 3630 and 129 5305. This ensures that the first bit of the EAG sub-TLV is always 130 bit 32, and ensures maximum interoperability with legacy 131 implementations. 133 2.3.2. Desire for unadvertised EAG bits 135 The existing AG bits are optional; thus a node may be configured with 136 a preference to include red or exclude blue, and be faced with a link 137 that is not advertising a value for either blue or red. What does an 138 implementation do in this case? It shouldn't assume that red is set, 139 but it is also arguably incorrect to assume that red is NOT set, as a 140 bit must first exist before it can be set to 0. 142 Practically speaking this has not been an issue for deployments, as 143 many implementations always advertise the AG bits, often with a 144 default value of 0x00000000. However, this issue may be of more 145 concern once EAGs are added to the network. EAGs may exist on some 146 nodes but not others, and the EAG length may be longer for some links 147 than for others. 149 Each implementation is free to choose its own method for handling 150 this question. However, to encourage maximum interoperability an 151 implementation SHOULD treat specified but unadvertised EAG bits as if 152 they are set to 0. A node MAY provide other (configurable) 153 strategies for handling this case. 155 3. Security Considerations 157 This extension adds no new security considerations. 159 4. IANA Considerations 161 This document requests a sub-TLV allocation in both OSPF and ISIS. 163 5. Acknowledgements 165 Thanks to Santiago Alvarez and Rohit Gupta for their review and 166 comments. 168 6. Normative References 170 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 171 Requirement Levels", BCP 14, RFC 2119, March 1997. 173 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 174 (TE) Extensions to OSPF Version 2", RFC 3630, 175 September 2003. 177 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 178 Engineering", RFC 5305, October 2008. 180 Author's Address 182 Eric Osborne 183 Cisco