Subject: Re: revised ethernet/802.xx input header processing.
To: Bill Sommerfeld <>
From: David Evans <>
List: tech-net
Date: 10/30/1999 23:45:21
Bill Sommerfeld wrote:
> This is for PPPoE support, right?   (you need access to the mac level
> src/destination addresses there, right?)

  Yes, you do, since you have to store the address of the Access Concentrator
for subsequent PAD. or data packets.

> PPPoE over 802.11 could get entertaining


> 802.11 frames start with 4 bytes of control information, including a
> packet type, followed by 3 6-byte MAC addresses, followed by another 2
> bytes of control info, followed by a LLC header.

  Then "straight" PPPoE over 802.11 wouldn't work, since RFC 2516 specifies
something that's pretty much directly tied to the Ethernet frame format we
all know and love.  From the sound of what you say in the rest of your
post PPPoE over 802.11 would require straight bridging by the wireless stuff
to an AC; the AC would then pull apart the frame as appropriate.

> Would passing pointers to src and dst addresses give PPPoE what it
> wants?

  Sure.  The PPPoE implementation itself only cares about seeing the address
of the peer.  It doesn't really matter what that value is as long as it's
consistent and the data gets to the right place.

David Evans          (NeXTMail/MIME OK)   
Computer/Synth Junkie            
University of Waterloo         "Default is the value selected by the composer
Ontario, Canada           overridden by your command." - Roland TR-707 Manual