Hi

Thanks Ted for the constructive suggestions, which remind me to try to 
understand the questions. Here are the questions I think give the clear 
suggestions for LC.

Brian: So could the draft make this explicit, because I guarantee you it is not 
in the least obvious to the non-expert reader?

Jinmei: it should say it updates this part of RFC8200 and explain why it's 
justified.

Joel: it would seem that there ought to be a good reason for including PSP, 
rather than claiming that objectors need to motivate removing it.

Bob: There seems to be questions about its relationship with RFC8200.  I am not 
seeing this as being resolved.

As far as I understand the concern and the draft, I may have the following 
proposed text, though I don’t know if that will help to close or narrow the gap:

****Proposed text to explicitly explain the PSP at the end of 4.16.1 of 
rev-10****

Note that, the SRH is used in an X-in-IP6 tunnel end point case, that is, 
router (A)
imposes an SRH, and a Penultimate Segment router (B) removes the SRH before
this packet goes to the tunnel end point router (C), so that the tunnel endpoint
router (C) doesn't have to deal with SRH.

This has some very important benefits for deployment in some networks when the
final tunnel end point is a lower-end node which is not capable of processing
the SRH for reasons like the hardware is overloaded or unable to upgraded to
process well with SRH.

The use of SRH with AH by an SR source node, and processing at a SR Penultimate
segment endpoint node is not defined in <draft-ietf-6man-segment-routing-header>
or in this document.

The use of PSP does not impact the MTU Considerations defined in section 5.3 of
<draft-ietf-6man-segment-routing-header>.

The design of PSP for the benefits of deployment is based on the understanding
that it does not violate section 4 of RFC8200. In case the RFC8200 text may be
modified in the future, the PSP may also need to change accordingly.

In case the final tunnel endpoint router is fully capable of the functionality
of SRH and the SRv6-NP defined in this document, it is recommended not to use
the PSP.

***End****

Thanks
Jingrong


From: spring [mailto:spring-boun...@ietf.org] On Behalf Of Ted Lemon
Sent: Friday, February 28, 2020 4:55 AM
To: Pablo Camarillo (pcamaril) <pcama...@cisco.com>
Cc: spring@ietf.org; 6...@ietf.org
Subject: Re: [spring] Request to close the LC and move forward//RE: WGLC - 
draft-ietf-spring-srv6-network-programming

On Feb 27, 2020, at 3:38 PM, Pablo Camarillo (pcamaril) 
<pcama...@cisco.com<mailto:pcama...@cisco.com>> wrote:
The discussion that we are having is about PSP which has nothing to do with 
that.

So, there is text in the document that addresses Brian’s question?

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