idnits 2.17.1 draft-ietf-idr-link-bandwidth-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (March 9, 2011) is 4769 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4893 (Obsoleted by RFC 6793) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Mohapatra 3 Internet-Draft R. Fernando 4 Intended status: Standards Track Cisco Systems 5 Expires: September 10, 2011 March 9, 2011 7 BGP Link Bandwidth Extended Community 8 draft-ietf-idr-link-bandwidth-02.txt 10 Abstract 12 This document describes an application of BGP extended communities 13 that allows a router to perform unequal cost load balancing. 15 Status of this Memo 17 This Internet-Draft is submitted in full conformance with the 18 provisions of BCP 78 and BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF). Note that other groups may also distribute 22 working documents as Internet-Drafts. The list of current Internet- 23 Drafts is at http://datatracker.ietf.org/drafts/current/. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 This Internet-Draft will expire on September 10, 2011. 32 Copyright Notice 34 Copyright (c) 2011 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents 39 (http://trustee.ietf.org/license-info) in effect on the date of 40 publication of this document. Please review these documents 41 carefully, as they describe your rights and restrictions with respect 42 to this document. Code Components extracted from this document must 43 include Simplified BSD License text as described in Section 4.e of 44 the Trust Legal Provisions and are provided without warranty as 45 described in the Simplified BSD License. 47 This document may contain material from IETF Documents or IETF 48 Contributions published or made publicly available before November 49 10, 2008. The person(s) controlling the copyright in some of this 50 material may not have granted the IETF Trust the right to allow 51 modifications of such material outside the IETF Standards Process. 52 Without obtaining an adequate license from the person(s) controlling 53 the copyright in such materials, this document may not be modified 54 outside the IETF Standards Process, and derivative works of it may 55 not be created outside the IETF Standards Process, except to format 56 it for publication as an RFC or to translate it into languages other 57 than English. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 63 2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3 64 3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3 65 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 66 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 67 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 68 7. Normative References . . . . . . . . . . . . . . . . . . . . . 4 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 71 1. Introduction 73 When a BGP speaker receives multiple paths from its internal peers, 74 it could select more than one path to send traffic to. In doing so, 75 it might be useful to provide the speaker with information that would 76 help it distribute the traffic unequally based on the bandwidth of 77 the external (DMZ) link. This document suggests that the external 78 link bandwidth be carried in the network using a new extended 79 community [RFC4360] - the link bandwidth extended community. 81 1.1. Requirements Language 83 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 84 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 85 document are to be interpreted as described in RFC 2119 [RFC2119]. 87 2. Link Bandwidth Extended Community 89 When a BGP speaker receives a route from an external neighbor and 90 advertises this route (via IBGP) to internal neighbors, as part of 91 this advertisement the router may carry the cost to reach the 92 neighbor. The cost can be either configured per neighbor or derived 93 from the bandwidth of the link that connects the router to a directly 94 connected external neighbor. This value is carried in the Link 95 Bandwidth Extended Community. No more than one link bandwidth 96 extended community SHALL be attached to a route. Additionally, if a 97 route is received with link bandwidth extended community and the BGP 98 speaker sets itself as next-hop while announcing that route to other 99 peers, the link bandwidth extended community should be removed. 101 The extended community is optional non-transitive. The value of the 102 high-order octet of the extended Type Field is 0x40. The value of 103 the low-order octet of the extended type field for this community is 104 0x04. The value of the Global Administrator subfield in the Value 105 Field SHOULD represent the Autonomous System of the router that 106 attaches the Link Bandwidth Community. If four octet AS numbering 107 scheme is used [RFC4893], AS_TRANS should be used in the Global 108 Administrator subfield. The bandwidth of the link is expressed as 4 109 octets in IEEE floating point format, units being bytes (not bits!) 110 per second. It is carried in the Local Administrator subfield of the 111 Value Field. 113 3. Deployment Considerations 115 The usage of this community is restricted to the cases where BGP 116 multipath can be safely deployed. In other words, the IGP distance 117 between the load balancing router and the exit points should be the 118 same. Alternatively, the path between the load sharing router and 119 the exit points could be tunneled. If there are multiple paths to 120 reach a destination and if only some of them have link bandwidth 121 community, the receiver should not perform unequal cost load 122 balancing based on link bandwidths. 124 4. Acknowledgments 126 The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan 127 Tappan for proposing unequal cost load balancing as one possible 128 application of the extended community attribute. 130 The authors would like to thank Bruno Decraene, Robert Raszuk, Joel 131 Halpern, and Aleksi Suhonen for their useful comments and 132 discussions. 134 5. IANA Considerations 136 This document defines a specific application of the two-octet AS 137 specific extended community. IANA is requested to assign a sub- type 138 value of 0x04 for the link bandwidth extended community. 140 Name Value 141 ---- ----- 142 non-transitive Link Bandwidth Ext. Community 0x4004 144 6. Security Considerations 146 There are no additional security risks introduced by this design. 148 7. Normative References 150 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 151 Requirement Levels", BCP 14, RFC 2119, March 1997. 153 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 154 Communities Attribute", RFC 4360, February 2006. 156 [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS 157 Number Space", RFC 4893, May 2007. 159 Authors' Addresses 161 Pradosh Mohapatra 162 Cisco Systems 163 170 W. Tasman Drive 164 San Jose, CA 95134 165 USA 167 Phone: 168 Email: pmohapat@cisco.com 170 Rex Fernando 171 Cisco Systems 172 170 W. Tasman Drive 173 San Jose, CA 95134 174 USA 176 Phone: 177 Email: rex@cisco.com