Re: [Bier] Benjamin Kaduk's Discuss on draft-ietf-bier-te-arch-10: (with DISCUSS and COMMENT)

Carsten Bormann <cabo@tzi.org> Wed, 22 December 2021 18:11 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Wed, 22 Dec 2021 19:11:07 +0100
Cc: The IESG <iesg@ietf.org>, gengxuesong@huawei.com, draft-ietf-bier-te-arch@ietf.org, Alvaro Retana <aretana.ietf@gmail.com>, bier-chairs@ietf.org, Benjamin Kaduk <kaduk@mit.edu>
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Subject: Re: [Bier] Benjamin Kaduk's Discuss on draft-ietf-bier-te-arch-10: (with DISCUSS and COMMENT)
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On 2021-08-26, at 08:59, Benjamin Kaduk via Datatracker <noreply@ietf.org> wrote:
> 
> pseudocode in Figure 6

I’m sorry, I’m not an expert about BIER-TE, so take the below with a grain of salt.

I ran into the pseudocode in a discussion we had about including pseudocode in an RFC.

The code I find is “almost C”; I don’t understand why you didn’t go the last mile so you can check what you did.

An indicator that gives away the code might have problems is the different spacing for
       SI=GetPacketSI(Packet);
       Offset=SI*BitStringLength;
(no spaces around operators) vs. much, but not all, of the rest.

But more importantly, what does this pseudocode mean:

           foreach adjacency BIFT[Index+Offset] {

Is there an “in” missing?
I learn from the explanation that the code "loops over the adjacencies because there may be more than one adjacency for a bit”, so maybe there is a mapping from a bit position (not the bit itself, which is 1 or 0) to a list of adjacencies?

What is the difference between commas inside and outside the {}?

                   case forward_routed({VRF},l3-neighbor):
                       SendToL3(PacketCopy,{VRF,}l3-neighbor);

These are questions that an implementer who is tasked to look at this pseudocode will have in all likelihood, so I would expect that the WG wants this clarified.

Grüße, Carsten