Re: Extension Header Insertion

["Darren Dukes (ddukes)" <[e-mail]>]

Hi Adrian. You failed to quote the section of rfc 8200 where it says “IPv6 nodes must accept and attempt to process extension headers in
   any order and occurring any number of times in the same packet,”

I do not agree with your assumptions nor the attempt to imply something about the Other drafts.

Darren.

________________________________
From: ipv6 <[e-mail]> on behalf of Adrian Farrel <[e-mail]>
Sent: Monday, December 9, 2019 4:34 AM
To: 'Ron Bonica'; '6man'
Subject: RE: Extension Header Insertion

Hi Ron,

I think we can jump to a quick answer on this because draft-ietf-spring-srv6-network-programming-05 says:

   We assume that the SRH may
   be present multiple times inside each packet.

Thus we may assume that the proponents of Extension Header insertion do think that it is acceptable to insert a second routing header into a packet that already has one.

And 8200 is clear when it says:
   Each extension header should occur at most once, except for the
   Destination Options header, which should occur at most twice (once
   before a Routing header and once before the upper-layer header).

So draft-ietf-spring-srv6-network-programming-05 includes a false assumption which need to be either removed or secured through an update to 8200.

Ideally, I suppose, draft-ietf-6man-segment-routing-header would have contained the clarification that the SRH could be present multiple times (updating 8200 as it went).

Cheers,
Adrian

From: ipv6 <[e-mail]> On Behalf Of Ron Bonica
Sent: 09 December 2019 03:04
To: 6man <[e-mail]>
Subject: Extension Header Insertion

Folks,

This question is posed primarily to the proponents of Extension Header insertion.

Do you think that it is acceptable to insert a second routing header into a packet that already has one, so the resulting packet looks like the following:


  *   IPv6 header
  *   SRH
  *   SRH
  *   Upper-layer header

Would this be common in TI-LFA?

                                                                      Ron



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