[Coral-dev] SNAP header

[Joerg Micheel]

On Mon, Mar 03, 2003 at 10:41:24PM -0800, David Moore wrote:
> On Tue, Mar 04, 2003 at 01:05:50AM -0500, Steve Bernard wrote:
> > It seems that the SNAP header is causing me to lose several bytes of L4 
> > data. I am currently using FORE-200E's so it's either 48-bytes or 
> > everything. My capture and storage requirements make the 'everything' 
> > impractical but, losing the L4 data makes the captures much less useful. 
> > Am I missing something, or is this something that will require some 
> > development with Perl and CRL.pm?
> 
> If your network has an LLC/SNAP header at the front of packets
> there is nothing you can do about that if you can only capture the
> first cell.  The first ATM cell only has 48 bytes, which includes
> that header.  Your other choice is to capture everything, but only
> write out part of what you see, for example changing crl_to_pcap
> to truncate packets at whatever length you desire.

Or capture the first two ATM cells of each AAL5 frame.

	Joerg
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