Internet-Draft Alan Watkins Network Working Group IBM Corp. Intended Status: Experimental February 28, 2007 Expires: September 1st, 2007 Updates: RFC 792 ICMP Type 11 Code 0 Enhancement Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 August 30th, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract When performing a traceroute, it would be useful to know where packets are trying to go when they cannot be routed. ICMP Type 11 Code 0 packets could be used to provide this information, and the traceroute facility could report this information. Watkins Standards Track [Page 1] Draft ICMP Type 11 Code 0 Enhancement February 2007 1. ICMP Type 11 Code 0 Enhancement When performing a traceroute, it would be useful to know where packets are trying to go when they cannot be routed. ICMP Type 11 Code 0 packets could be used to provide this information, and the traceroute facility could report this information. Basically, next hop information could be included in ICMP type 11, code 0 messages and this would allow for further remote analysis of network problems. ICMP error messages carry a variety of information; the concept behind the traceroute program is to send messages with increasing TTL values so that each router along the path will return a Type 11 Code 0 message and the traceroute program can use this to incrementally print out the path from the source IP address to the destination IP address. When something goes wrong, traceroute reports the last router it could successfully reach. The idea presented here would give one more piece of information, namely where a packet was trying to go when it failed. The format of an ICMP Type 11 Code 0 message is [RFC792]: Time Exceeded Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | unused | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Internet Header + 64 bits of Original Data Datagram | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The unused part of this packet will exactly fit an IPv4 IP address. If the IP address that gets filled in happens to be the IP address of the next hop that would have been taken if the TTL hadn't been exceeded, the originator can use this information in a variety of ways. One interesting way would be for the traceroute facility to print this next hop information out: Watkins Standards Track [Page 2] Draft ICMP Type 11 Code 0 Enhancement February 2007 #traceroute www.foo.com Tracing route to www.foo.com [192.168.0.150] over a maximum of 30 hops: Next Hop 1 2 ms 2 ms 2 ms 10.1.1.1 10.1.2.1 2 10 ms 10 ms 23 ms 10.1.2.1 10.1.3.1 3 9 ms 11 ms 9 ms 10.1.3.1 192.168.0.1 4 12 ms 9 ms 9 ms 192.168.0.1 1.1.1.1 5 * * * Request timed out Even with just this additional information, we now know that there is a problem between 192.168.0.1->1.1.1.1. Maybe 1.1.1.1 is not the right hop (bad routing entry on 192.168.0.1) or maybe the link between these routers is down. Before, we didn't know anything about 1.1.1.1 being in the picture. A user with this problem may have no knowledge of 1.1.1.1, but maybe it is their router...so perhaps this would point to a configuration problem on a router they control. This information wouldn't have been available otherwise. If the other side (in this case www.foo.com) does a traceroute and receives something similar to: 1 24 ms 28 ms 27 ms 192.168.0.150 1.1.1.1 2 27 ms 24 ms 55 ms 1.1.1.1 192.168.0.1 3 * * * Request timed out We can now pretty much be sure that the problem is with the 192.168.0.1 - 1.1.1.1 link. If one of the routers along the path doesn't support this, the only negative thing would be that the information wouldn't be available for that particular router. This allows for backwards compatibility with existing routers. To extend this idea to IPv6 would most likely require an additional ICMP message type. Normative References [RFC792] Postel, J., "Internet Control Message Protocol", RFC 792, September 1981. Watkins Standards Track [Page 3] Draft ICMP Type 11 Code 0 Enhancement February 2007 Author's Address Alan Watkins IBM Corp. Email: watkinal@us.ibm.com Full Copyright Statement Copyright (C) The IETF Trust (2007). 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Watkins Standards Track [Page 4]