Subject: [Ips] FW: RFC 4963 on IPv4 Reassembly Errors at High Data Rates

From: [email-masked]
Date: Sun, 29 Jul 2007 21:56:41 -0400

FYI - IPv4 fragmentation can be harmful at high speed.  The
best bet is to not to allow fragmentation, but the RFC says:
"stronger error checking at any level above IP" is a mitigation
measure.  iSCSI digests and the end-to-end use of the FC frame
CRC by FCIP and iFCP are examples of this sort of "stronger
error checking".

--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
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-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Friday, July 27, 2007 5:34 PM
To: [email-masked]; [email-masked]
Cc: [email-masked]
Subject: RFC 4963 on IPv4 Reassembly Errors at High Data Rates

A new Request for Comments is now available in online RFC libraries.

        RFC 4963

        Title:      IPv4 Reassembly Errors at High 
                    Data Rates 
        Author:     J. Heffner, M. Mathis,
                    B. Chandler
        Status:     Informational
        Date:       July 2007
        Mailbox:    [email-masked], 
                    [email-masked], 
                    [email-masked]
        Pages:      10
        Characters: 22399
        Updates/Obsoletes/SeeAlso:   None

        I-D Tag:    draft-heffner-frag-harmful-05.txt

        URL:        http://www.rfc-editor.org/rfc/rfc4963.txt

IPv4 fragmentation is not sufficiently robust for use under some
conditions in today's Internet.  At high data rates, the 16-bit IP
identification field is not large enough to prevent frequent
incorrectly assembled IP fragments, and the TCP and UDP checksums are
insufficient to prevent the resulting corrupted datagrams from being
delivered to higher protocol layers.  This note describes some easily
reproduced experiments demonstrating the problem, and discusses some
of the operational implications of these observations.  This memo
provides information for the Internet community.

INFORMATIONAL: This memo provides information for the Internet
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It does not specify an Internet standard of any kind. Distribution
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