Subject: Re: ip_flow.c
To: Kevin M. Lahey <>
From: Andrew Brown <>
List: tech-net
Date: 01/29/1999 02:25:12
On Thu, Jan 28, 1999 at 05:59:03PM -0800, Kevin M. Lahey wrote:
>I'd love to hear conflicting opinions (and I wasn't yet convinced
>that incremental checksum updating violated RFC1812, anyway).

ny interpretation of the rfc and the specific placement of the words
"MUST" and "MAY" makes me think that it "has" to be checked, but
"doesn't necessarily have" to be recalculated after the ttl has been
changed.  so you have to compute it only once.  but you have to
compute it at least once.

1812 allows incremental updating.  it doesn't exactly encourage it,
but it does say it's allowed.

|-----< "CODE WARRIOR" >-----|             * "ah!  i see you have the internet (Andrew Brown)                that goes *ping*!"       * "information is power -- share the wealth."