Subject: Re: PPPmux and MP

From: [email-masked]
Date: Sun, 2 Jul 2000 11:09:21 -0500

I'd also suggest that if you update the draft-ietf-pppext-pppmux-00.txt to
include a reference to the compound frames LCP option described in RFC 1570
and consider pros, cons and interoperability of pppmux versus the LCP
compound frames option. The goals of both options seem to be related, no?

Speaking as an implementer, I'd also appreciate more justification for
adding extra complexity to my implementation to save a few bytes during
transmission.  My personal opinion is that hacking off a few bytes from a
packet never manifests itself as a performance improvement my customers
will notice. I think optimizations such as this are more effectively
performed by the hardware at the physical link layer, not by the protocol
software. Consequently, I currently would never implement either of these
LCP options.

I'd be interested in hearing the opinions and/or experiences from anyone
whose implementation does/would support either compound frames or pppmux.
Is it "worth it"? Why?

-john martz,   [email-masked]
IBM AS/400 TCP/IP PPP development (and stuff)

---

From: James Carlson <[email-masked]>
Date: Sun, 2 Jul 2000 12:56:14 -0400 (EDT)

> compound frames option. The goals of both options seem to be related, no?

PPPmux is extremely similar, but a little better.  It goes to some
effort to eliminate as much overhead as possible by recognizing that
most links have long chains of packets using a single protocol number.

> will notice. I think optimizations such as this are more effectively

It depends on what you're doing.  The original justification for
PPPmux was that it brings Voice over IP overhead more in line with the
overhead expected for plain voice calls and thus makes it more
practical for wireless use.  I'm not an expert in wireless VoIP, so I
really can't comment on that aspect.  It does reduce the PPP overhead
to the minimum possible, and at least I can imagine applications where
bits on the wire are far more expensive than any computational
complexity.

Like compound-frames, I don't see a burning need for it either, and
I'm not rushing to implement it.

-- 
James Carlson, Internet Engineering       <[email-masked]>
SUN Microsystems / 1 Network Drive         71.234W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.497N   Fax +1 781 442 1677
"PPP Design and Debugging" --- http://people.ne.mediaone.net/carlson/ppp

---

From: Tmima Koren <[email-masked]>
Date: Sun, 02 Jul 2000 09:59:33 -0700

>whose implementation does/would support either compound frames or pppmux.

Multiplexing is useful when the PPP packets are tunneled: 
the overhead of the tunneling header is amortized over the multiplexed packets 
see: http://www.ietf.org/internet-drafts/draft-ietf-avt-tcrtp-00.txt
Tmima