Re: [VRRP] RFC5798 - clarification on checksum calculation

Tomoyuki Sahara <sahara@surt.net> Mon, 02 April 2012 11:41 UTC

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From: Tomoyuki Sahara <sahara@surt.net>
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Date: Mon, 2 Apr 2012 20:41:51 +0900
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Subject: Re: [VRRP] RFC5798 - clarification on checksum calculation
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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