Subject: RE: LINK (Advice for Internet Subnetwork Designers)

From: "Lai, Wai S (Waisum), ALSVC" <[email-masked]>
Date: Fri, 2 Mar 2001 16:00:09 -0500

Phil and Joe,
   Many thanks for the responses of you two on my proposals.
I appreciate them very much.
   My purpose of introducing the text is two-fold:
(1) DOCSIS is a widely used protocol and hence I think it should be
    mentioned in LINK.
(2) There are two aspects to DOCSIS regarding its treatment of large
    MTU. (A) DOCSIS 1.1 uses internal fragmentation/reassembly, just
    like other protocols.  So, in terms of protocol feature,
    you are right that there's nothing new here, other than mentioning
    that DOCSIS is another example.
    (B) The new twist is the need to provide backward compatibility
    under the co-existence of both DOCSIS 1.0 and DOCSIS 1.1 where
    some cable modems will not be able to do fragmentation.
    In this case, it has been demonstrated the use of special bandwidth
    allocation algorithm and careful capacity engineering can make it
    to work.
It is the (2B) aspect that I think is an option for subnet designers
that has not been discussed or emphasized in LINK.  I hope this answers
somewhat the points you raised.  Please let me know if I should further
clarify.
   Thanks again for your valuable input and help to accommodate my
request.
Thanks, Waisum. 

>Can this text be condensed to its generalities? I think PILC already
>deals with upstream BW and QOS issues in link design. What is the new
>aspect here?

>(other than be careful in your first protocol; backward compatibility
>can be difficult)

>Joe

-----Original Message-----
From: Phil Karn [mailto:[email-masked]]
Sent: Friday, March 02, 2001 3:36 PM
To: Lai, Wai S (Waisum), ALSVC
Cc: [email-masked]; [email-masked]; [email-masked];
[email-masked]; [email-masked]; [email-masked];
[email-masked]; [email-masked]
Subject: Re: LINK (Advice for Internet Subnetwork Designers)

Rather than include your text as-is, I summarized your comments about
DOCSIS as follows:

Another example of link-layer multiplexing is the Data Over Cable
Service Interface Specifications. [DOCSIS1] [DOCSIS2] [DOCSIS3] DOCSIS
version 1.1 introduces an internal fragmentation and reassembly
procedure so that real-time voice packets can avoid undue delay when
sharing the relatively slow upstream channel of a cable modem with
large data packets.

I also added the three references you cited.

Phil