RFC5798 - clarification on checksum calculation

Hermin Anggawijaya <[email protected]> Thu, 29 Mar 2012 20:29:49 +1300

Newsgroups	gmane.ietf.vrrp
Message-ID	<CAJgsEzVnofJ+Fm_eHgpHcZu8+Xuj2ZwEYT_Dy9wbovcVQzfWiA@mail.gmail.com>

Would someone be able to help clarifying RFC5798 Sec. 5.2.8 on
checksum for me please...

It says that

  "The checksum is the 16-bit one's complement of the one's complement
   sum of the entire VRRP message starting with the version field and a
   "pseudo-header" as defined in Section 8.1 of [RFC2460].  The next
   header field in the "pseudo-header" should be set to 112 (decimal)
   for VRRP.  For computing the checksum, the checksum field is set to
   zero.  See RFC1071 for more detail [RFC1071]."

My interpretation of the above clause is, for IPv4 VRRP the checksum would be
defined as:

"The checksum is the 16-bit one's complement of the one's complement
 sum of the entire VRRP message starting with the version field"

as per RFC 3768, instead of involving "pseudo header" (as defined in
Section 8.1 of [RFC2460]).

If my interpretation is correct, would it be useful to change the text to
reflect specific checksum detail for IPv4 ?


Regards

Angga
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