Subject: Re: [Hubmib] FW: RFC 2665 comments

From: RJ Atkinson <[email-masked]>
Date: Tue, 13 Mar 2001 19:17:52 -0500

At 17:23 13/03/01, Dan Romascanu wrote:
>Randy Presuhn did a reading of RFC 2665, in search for editorial and
>technical issues that we might want to deal with in the review process of this document. Please find below his findings.

Thanks to Randy for undertaking that review.

>>         page 7:  will the ifMtu need any changes?

In practice, in real networks and widely available shipping
product, the IEEE standard MTU for Ethernet is less than
the actual configurable as-implemented/as-deployed MTU.

In particular, for many of the reasons described in RFC-1626,
a very large set of host and switch/router vendors are supporting
an Ethernet MTU of ~9K (roundly speaking: 9180 bytes + L2 overhead).
For performance reasons on hosts (which have a per-packet 
cost that tends to be the actual performance bottleneck on
1-10 Gbps Ethernet), many folks have configured the larger
(notionally outside the IEEE 802 spec) ~9K MTU on at least
some interfaces.

When examining the SNMP MIB on such a device, it would be 
operationally variable if the "ifMtu" object reported the
actual in-use configured MTU on the interface, whether
that was lower or higher than the theoretical 1518 byte
limit of IEEE standard Ethernet.

So I would propose editing the current text around that
part of the revised document noting that the standard value
would be 1518 bytes, but that larger or smaller values ARE
seen in the wild, and indicating that the actual in-use
configured MTU value should be reported via the ifMtu object.

Maybe I'm missing something obvious here ?

>>         page 7:  here and in other places, it would be nice if
>>                  there were a reference for the MAU MIB.

        Agree.  There has been confusion about whether the MAU MIB
is to be implemented.  Reducing that confusion would be good.
Text sprinkled here and there would help a lot.

Ran
[email-masked]

_______________________________________________
Hubmib mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/hubmib

---

From: John Flick <[email-masked]>
Date: Tue, 13 Mar 2001 17:04:33 -0800

> Thanks to Randy for undertaking that review.

Yes, thank you Randy.  His comments were quite useful.

> Maybe I'm missing something obvious here ?

No, I don't think you are missing anything.  ifMtu should
report the MTU that is actually in use, regardless of whether it
matches the IEEE official MTU or not, and this text definitely
should say that.

John