RFC 1624 (rfc1624) - Page 1 of 6
Computation of the Internet Checksum via Incremental Update
Alternative Format: Original Text Document
Network Working Group A. Rijsinghani, Editor
Request for Comments: 1624 Digital Equipment Corporation
Updates: 1141 May 1994
Category: Informational
Computation of the Internet Checksum
via Incremental Update
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Abstract
This memo describes an updated technique for incremental computation
of the standard Internet checksum. It updates the method described
in RFC 1141.
Table of Contents
1. Introduction .......................................... 1
2. Notation and Equations ................................ 2
3. Discussion ............................................ 2
4. Examples .............................................. 3
5. Checksum verification by end systems .................. 4
6. Historical Note ....................................... 4
7. Acknowledgments ....................................... 5
8. Security Considerations ............................... 5
9. Conclusions ........................................... 5
10. Author's Address ..................................... 5
11. References ........................................... 6
1. Introduction
Incremental checksum update is useful in speeding up several
types of operations routinely performed on IP packets, such as
TTL update, IP fragmentation, and source route update.
RFC 1071, on pages 4 and 5, describes a procedure to
incrementally update the standard Internet checksum. The
relevant discussion, though comprehensive, was not complete.
Therefore, RFC 1141 was published to replace this description
on Incremental Update. In particular, RFC 1141 provides a
more detailed exposure to the procedure described in RFC 1071.
However, it computes a result for certain cases that differs
Rijsinghani