Subject: Re: Clarification request for proposed IETF draft "PPP BCP Issue 0.3 (February 2000)"

From: Fred Baker <[email-masked]>
Date: Tue, 22 Feb 2000 14:40:28 -0800

At 05:02 PM 2/22/00 +0000, Ewart Tempest wrote: 
>
> I request a qualification be added to the IETF draft in that there are no
> explicit texts in the document that specify whether Ethernet encapsulated
> frames sent over POS links, and encoded as per sections
> 4.2(untagged)/4.3(tagged), must be padded out to the minimum frame length
> required for 802.3.

I should think that if the message contains an e2e FCS, it would have to be
able to be transmitted on any wire unaltered. If it doesn't contain one, it
would not be so constrained. Can you explain why that would not be true?

---

From: Fred Baker <[email-masked]>
Date: Wed, 23 Feb 2000 08:50:59 -0800

At 06:58 AM 2/23/00 +0000, Ewart Tempest wrote: 
>
> So for bridged data, what you say above is clearly true. For PDUs which
> purely have point-to-point significance, like BPDUs, the need to have these
> padded to the minimum Ethernet frame length is less clear (e.g. TCN BPDU data
> length 4 bytes => would need to add 42 bytes of pad if Ethernet frame not
> tagged). To remove any ambiguity, I would like to see an explicit statement
> wrt minimum length of the LLC data field.

So you have proposed that they always be augmented, and you have agreed with me
that such is unnecessary. If it is unnecessary and it is done, there is no
harm, and if it is not done, there is no harm.

Which leaves me really confused. Yes, we can put in a sentence, but would there
be an interoperability impact if someone ignored it? Is there any combination
which gets all the user or control traffic through and which is
non-interoperable with the other solutions?

Maybe it's just me, but I'm not fond of specifying things that don't need to be
specified. My experience is that they lead to fruitless arguments about what
the sentence should say and why, and fail to promote interoperability. What I'd
like to hear is a case where it is important to have this specified.