Ethereal-dev: Re: [Ethereal-dev] PPP dissector bug

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From: Irfan Khan <ikhan@xxxxxxxxxxxx>
Date: Mon, 10 Mar 2003 19:56:19 -0700
Yup, these are framing bytes. I thought it better to put the check for any unexpected 0x7e s in packet-ppp to make it more bug-proof :) 

Guy Harris wrote:


On Mon, Mar 10, 2003 at 07:38:08PM -0700, Irfan Khan wrote:
I was looking at a log, using ethereal, where the packets were PPP over L2TP. The L2TP dissector was calling the PPP HDLC handler correctly however the PPP dissector was unable to make make sense of the packets because they had a 0x7e in the beginning. 

What are the 0x7e's?  They're presumably not framing bytes, as RFC 2661
says:

	5.3 Forwarding PPP Frames

	   Once tunnel establishment is complete, PPP frames from the remote
	   system are received at the LAC, stripped of CRC, link framing, and
	   transparency bytes, encapsulated in L2TP, and forwarded over the
	   appropriate tunnel. The LNS receives the L2TP packet, and processes
	   the encapsulated PPP frame as if it were received on a local PPP
	   interface.