Subject: [Pppext] Address and Control Field Compression in RFC 1661

From: "Couch, William Garrant, JR (Garry)" <[email-masked]>
Date: Wed, 18 Jan 2006 11:18:17 -0500

PPPEXTers,

I'm hoping that one or more of you can shed some light on section 6.6, Address and Control Field Compression, in RFC 1661.  Is this intended to refer to a specific compression method, a general compression method, or just to the dropping of prefixed zero octets (as in the previous section, 6.5, on Protocol Field Compression)?

Garry Couch
System Engineer
CDMA Radio Access Networks
Whippany, NJ
973 386-7437

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From: James Carlson <[email-masked]>
Date: Wed, 18 Jan 2006 11:31:33 -0500

> I'm hoping that one or more of you can shed some light on section 6.6, Address and Control Field Compression, in RFC 1661.  Is this intended to refer to a specific compression method, a general com…

It refers only to the _removal_ of the HDLC Address and Control fields
from the frames.  It has nothing to do with data compression or zero
octets.

The Address and Control field values are (assuming you're not using
Frame Relay, RFC 1663, or some other HDLC-based scheme that relies on
those fields) a fixed hex FF 03 on each packet.  Since "FF 03" can
never be a legal protocol number, it's safe to just discard those two
bytes -- omit them entirely from the datagram sent on the wire.  This
option negotiates that feature.

-- 
James Carlson, KISS Network                    <[email-masked]>
Sun Microsystems / 1 Network Drive         71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677