Re: [VRRP] RFC5798 - clarification on checksum calculation

kura@iij.ad.jp Tue, 15 May 2012 02:41 UTC

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Date: Tue, 15 May 2012 11:41:48 +0900 (JST)
Subject: Re: [VRRP] RFC5798 - clarification on checksum calculation
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Hello list,

Has there been any progress with regard to this topic?
I know that in an implementation of VRRPv3 for IPv4 the checksum
is calculated without pseudo-header currently, but I believe that
pseudo-header should be involved in the calculation as same as
IPv6 case.

Regards,
-- 
Tomohiko Kurahashi <kura@iij.ad.jp>;


From: sahara@surt.net
Date: Mon Apr 02 2012 20:41:51 JST
>
> Forwarded.
> Any other VRRPv3/IPv4 implementation?
> 
> 
> Thanks,
> Tomoyuki
> 
> 
> Date: Mon, 2 Apr 2012 03:26:15 +0200
> Subject: Re: [VRRP] RFC5798 - clarification on checksum calculation
> From: Hermin Anggawijaya <hermin.anggawijaya@gmail.com>;
> To: Tomoyuki Sahara <sahara@surt.net>;
> 
> Sahara-san
> 
> Thanks for your input.
> 
> Anyone else with either/other interpretation of the clause ?
> 
> 
> Thanks
> 
> On Mon, Apr 2, 2012 at 1:48 AM, Tomoyuki Sahara <sahara@surt.net>; wrote:
> > Hi,
> > 
> > On Thu, Mar 29, 2012 at 4:29 PM, Hermin Anggawijaya
> > <hermin.anggawijaya@gmail.com>; wrote:
> >> 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]).
> > 
> > My understanding is only reference text ("as defined in Section 8.1 of
> > [RFC2460]") is irrelevant for IPv4.  Our implementation calculates checksum
> > including pseudo header as for TCP/UDP/DCCP.
> > 
> >> If my interpretation is correct, would it be useful to change the text to
> >> reflect specific checksum detail for IPv4 ?
> > 
> > My interpretation is different from yours but clarification should be
> > very useful.
> > It's vital for interoperable implementations of VRRPv3/IPv4.
> > 
> > 
> > Thanks,
> > Tomoyuki