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TCP Problems with Path MTU Discovery (RFC2923)

IP.com Disclosure Number: IPCOM000005105D
Original Publication Date: 2000-Sep-01
Included in the Prior Art Database: 2001-Aug-15
Document File: 16 page(s) / 31K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

K. Lahey: AUTHOR

Abstract

This memo catalogs several known Transmission Control Protocol (TCP) implementation problems dealing with Path Maximum Transmission Unit Discovery (PMTUD), including the long-standing black hole problem, stretch acknowlegements (ACKs) due to confusion between Maximum Segment Size (MSS) and segment size, and MSS advertisement based on PMTU.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 11% of the total text.

Network Working Group K. Lahey Request for Comments: 2923 dotRocket, Inc. Category: Informational September 2000

TCP Problems with Path MTU Discovery

Status of this Memo

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

Copyright Notice

Copyright (C) The Internet Society (2000). All Rights Reserved.

Abstract

This memo catalogs several known Transmission Control Protocol (TCP) implementation problems dealing with Path Maximum Transmission Unit Discovery (PMTUD), including the long-standing black hole problem, stretch acknowlegements (ACKs) due to confusion between Maximum Segment Size (MSS) and segment size, and MSS advertisement based on PMTU.

1. Introduction

This memo catalogs several known TCP implementation problems dealing with Path MTU Discovery [RFC1191], including the long-standing black hole problem, stretch ACKs due to confusion between MSS and segment size, and MSS advertisement based on PMTU. The goal in doing so is to improve conditions in the existing Internet by enhancing the quality of current TCP/IP implementations.

While Path MTU Discovery (PMTUD) can be used with any upper-layer protocol, it is most commonly used by TCP; this document does not attempt to treat problems encountered by other upper-layer protocols. Path MTU Discovery for IPv6 [RFC1981] treats only IPv6-dependent issues, but not the TCP issues brought up in this document.

Each problem is defined as follows:

Name of Problem The name associated with the problem. In this memo, the name is given as a subsection heading.

Lahey Informational [Page 1]

RFC 2923 TCP Problems with Path MTU Discovery September 2000

Classification One or more problem categories for which the problem is classified: "congestion control", "performance", "reliability", "non-interoperation connectivity failure".

Description A definition of the problem, succinct but including necessary background material.

Significance A brief summary of the sorts of environments for which the problem is significant.

Implications

Why the problem is viewed as a problem.

Relevant RFCs The RFCs defining the TCP specification with which the problem conflicts. These RFCs often qualify behavior using terms such as MUST, SHOULD, MAY, and others written capitalized. See RFC 2119 for the exact interpretation of these terms.

Trace file demonstrating the problem One or more ASCII trace files demonstrating the problem, if applicable.

Trace file demonstrating correct behavior One or more examples of how correct behavior appears in a trace, if applicable.

References

References that further discuss the problem.

How to detect How to test an implementation to see if it exhibits the problem. This discussion may include difficulties and subtleties ...