Network Working Group INTERNET-DRAFT Manayya KB Intended status:Proposed Standard Ericsson INC Expires: Aug 31, 2010 Feb 28, 2010 RIP Version 3 draft-manayya-ripv3-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on Aug 31, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document updates RFC 2453. This document adds details about selecting the route using bandwidth as metric in addition to traditional metric of hop count Manayya KB Expires Aug 31, 2010 [Page 1] Table of Contents 1. Introduction..................................................2 2. Implementation approach.......................................3 3. RIPv3 Message Format.......................................... 4. Route selection procedure.....................................5 5. IANA Considerations...........................................8 6. Security Considerations.......................................8 7. References....................................................8 1. Introduction This draft uses 2 types of metrics to select the route. one is traditional hop count (H) and the other metric uses bandwidth (B). 2. Implementatin approach This draft uses the following topology R1--(1Gbps)---R2----(1Gbps)----R3---|N | | |___________(10Mbps)__________| By default RIPv2 selects the routes based upon hop count. In the above diagram R1 learns the network N through both R2 and R3. Metric for the route learnt through R2 is 2 whereas metric for the network learnt through R3 is 1. Hence according to RIPv2 the next hop for N is R3 through 10Mbps link. Though the faster link is available, Slow link is selected and used to forward the traffic. To overcome this problem, Bandwidth metric (B) parameter is used in RIPv3 packet. In RIPv2, metric field uses 4 bytes. But maximum hop count in RIP is 16. Hence 5 bits are sufficient to represent hop count. Hence out of 4 bytes, 2 bytes can be used for metric (hop count H) and 2 more bytes can be used for bandwidth metric(B) Manayya KB Expires Aug 31, 2010 [Page 2] 3.RIPv3 Message Format This format is similar to RIPV2 packet format except Metric field The RIPv3 packet format is: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | command (1) | version (1) | must be zero (2) | +---------------+---------------+-------------------------------+ | | ~ RIP Entry (20) ~ | | +---------------+---------------+---------------+---------------+ There may be between 1 and 25 (inclusive) RIP entries. A RIP-1 entry has the following format: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | address family identifier (2) | must be zero (2) | +-------------------------------+-------------------------------+ | IPv4 address (4) | +---------------------------------------------------------------+ | must be zero (4) | +---------------------------------------------------------------+ | must be zero (4) | +---------------------------------------------------------------+ | Bandwidth metric (B)| hop count metric( H) | +---------------------------------------------------------------+ Bandwidth Metric - Metric calculated based upon bandwidth. The method of calculating metric is mentioned in section 5 Hop count metric - This is same as RIPv2 ( RFC 2453) bandwidth metric must be based upon IANA values 4. Route selection procedure Whenever router receives the update from neigbors, the following steps must be taken before inserting the netowrk into routing table. If the particluar update is received from only one neighbor, then only hop count metric must be considered. Manayya KB Expires Aug 31, 2010 [Page 3] If more than one next hops are available for the same network, Check for the hop count metric field(H) of updates. If all the updates have hop count metric value as 16 then mark that route as unreachable, if some of the hop count metric is/are 16, ignore the updates which have hop count metric 16 and compare the value of bandwidth metrics (B) of remaining updates, select the lowest bandwidth metric and insert that route into the routing table. If more than or equal to 2 routes have same bandwidth metric and Hop count metric (less than 16), then insert all those routes into routing table and use ECMP to forward traffic. If more than or equal to two routes have same bandwidth metric but different hop count metric, then select the route which has less value for hop count metric. In the above topology, R3 advertises network N to R2 and R1, when R2 receives the update, it checks for the bandwidth of interface on which it has received and add the bandwidth metric (4) to that route and send it to R1. When R1 receives the updated hop count metric will be 2 and bandwidth metric is (4+4 considering 4 for 1 GIG bandwidth) whereas route received from R3 in R1 has hop count metric as 1 and bandwidth metric is 100. So R1 has 2 updates, one with hop count metric 1 and bandwidth metric 100, second one with hop count metric 2 but bandwidth metric 8. As none of the routes have metric 16, selection will be based upon bandwidth metric i,e bandwidth metric 8 is preffered over 100. So next hop is R2. In this way, RIPv3 can overcome the limitation of RIPv2. 5. IANA Considerations IANA has to assign the following cost in consultation with the IESG. Bandwidth Metric 4 Mbit/s 250 10 Mbit/s 100 16 Mbit/s 62 100 Mbit/s 19 1 Gbit/s 4 2 Gbit/s 3 10 Gbit/s 2 Manayya KB Expires Aug 31, 2010 [Page 4] 6. Security Considerations The security considerations listed in RIPv2 [2453] are applicable 7. References [2453] G. Malkin, "RIP Version 2" RFC 2453, November 1998. Author's Address Manayya KB Ericsson INC Sanjose Email: manayya.a.bellignur@ericsson.com Manayya KB Expires Aug 31, 2010 [Page 5]