Browse Prior Art Database

IESG Advice from Experience with Path MTU Discovery (RFC1435)

IP.com Disclosure Number: IPCOM000002263D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2019-Feb-10
Document File: 2 page(s) / 2K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Knowles: AUTHOR

Related Documents

10.17487/RFC1435: DOI

Abstract

In the course of reviewing the MTU Discovery protocol for possible elevation to Draft Standard, a specific operational problem was uncovered. The problem results from the optional suppression of ICMP messages implemented in some routers. This memo outlines a modification to this practice to allow the correct functioning of MTU Discovery. This memo provides information for the Internet community. It does not specify an Internet standard.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 65% of the total text.

Network Working Group S. Knowles Request for Comments: 1435 ftp Software March 1993

IESG Advice from Experience with Path MTU Discovery

Status of this Memo

This memo provides information for the Internet community. It does not specify an Internet standard. Distribution of this memo is unlimited.

Abstract

In the course of reviewing the MTU Discovery protocol for possible elevation to Draft Standard, a specific operational problem was uncovered. The problem results from the optional suppression of ICMP messages implemented in some routers. This memo outlines a modification to this practice to allow the correct functioning of MTU Discovery.

Advice on the Deployment of Path MTU Discovery Protocol

While reviewing the Path MTU Discovery Protocol for Draft Standard [RFC1191], the Internet Engineering Steering Group (IESG) became aware from the reports of various implementors that some vendors have added to their routers the ability to disable ICMP messages generated by the router. This is to protect older BSD hosts, which would drop all connections to a host it found an ICMP message on any of the connections, even if it was a non-fatal ICMP message. While this protects older BSD hosts, it causes MTU discovery to fail in a silent, hard to diagnose way.

From the descriptions the IESG has obtained, adjusting the routers to continue to send ICMP message Type 3 code 4 (destination unreachable, don’t fragment (DF) bit sent and fragmentation required) even when they have their "don’t send...

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