Re: [mpls] What percentage will carry indicator/ancillary data in the future

[Haoyu Song <[e-mail]>]

Hi Kireeti,

Could you explain what's the difference between the following 01"SHOULD" and 10"MUST" and why you need to make the difference?
In a previous discussion, I suggested the following:

00: No PSD
01: illegal code
10: Has PSD, but only end-to-end type, so a transit node could ignore it.
11: Has PSD, and has Hop-by-hop type

Here the first bit is the PSD indicator and the second bid provides some useful further clarification. Is there any issue about it? Thanks!

Best regards,
Haoyu



From: mpls <[e-mail]> On Behalf Of Kireeti Kompella
Sent: Monday, October 11, 2021 11:23 AM
To: Greg Mirsky <[e-mail]>
Cc: [e-mail]
Subject: Re: [mpls] What percentage will carry indicator/ancillary data in the future

Here's what I'm thinking for the next iteration of the draft.  We'll burn two bits for hbh and e2e.  I propose the following encoding:
00 - No PSD (go back to sleep)
01 - if you are a transit or end node, you SHOULD look at the PSD
10 - if you are a transit or end node, you MUST look at the PSD (use with care)
11 - if you are a transit node, nothing interesting for you in the PSD; if you are an end node, look at the PSD.  (i.e., no hbh, only e2e PSD).

Note that in the naive approach:
00 - no PSD
01 - only hbh PSD
10 - only e2e PSD
11 - both hbh & e2e PSD

The action for 01 and 10 is pretty much the same.

Thoughts?

Kireeti.


On Oct 11, 2021, at 10:48, Kireeti Kompella <[e-mail]<mailto:[e-mail]>> wrote:

Hi Greg,

There were separate indicators for h-by-h and e2e.  The e2e was removed following discussion in the DT; it will return in the next revision.

Of course, the PSD carried and the processing needed will be different in the two cases as they carry different types of data.  Processing h-by-h will also have to deal with traversing a potentially large label stack (and occurs on many nodes), whereas processing e2e PSD will deal with a small label stack and just one node (the egress).

:k


On Oct 11, 2021, at 09:27, Greg Mirsky <[e-mail]<mailto:[e-mail]>> wrote:

Hi Loa,
I have a clarification question. As I understand it, FAI is to signal ancillary data that is processed in hop-by-hop or end-to-end manner (John proposed to have a separate indicator for each use case). The impact on transit nodes is, likely, different. Do you think we need to consider these cases separately?

Regards,
Greg

On Sat, Oct 9, 2021 at 10:43 AM Loa Andersson <[e-mail]<mailto:[e-mail]>> wrote:
Design Team,

I have one thing that I been thinking about.

If we consider future mpls encapsulated packet, what percentage will
carry indicators and ancillary data?

/Loa
--

Loa Andersson                        email: [e-mail]<mailto:[e-mail]>
Senior MPLS Expert                          [e-mail]<mailto:[e-mail]>
Bronze Dragon Consulting             phone: [phone]

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