Re: Question on draft-ietf-6man-segment-routing-header-04 (not needed PHP-Style behavior)

"Stefano Previdi (sprevidi)" <sprevidi@cisco.com> Wed, 01 February 2017 20:12 UTC

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From: "Stefano Previdi (sprevidi)" <sprevidi@cisco.com>
To: Shay Zadok <shay.zadok@broadcom.com>
Subject: Re: Question on draft-ietf-6man-segment-routing-header-04 (not needed PHP-Style behavior)
Thread-Topic: Question on draft-ietf-6man-segment-routing-header-04 (not needed PHP-Style behavior)
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Date: Wed, 1 Feb 2017 20:12:44 +0000
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Hi,


> On Feb 1, 2017, at 12:34 PM, Shay Zadok <shay.zadok@broadcom.com> wrote:
> 
> Hi,
> 
> As 'Clean-up flag' is omitted from segment-routing-header-04, does this means that no need to support PHP-Style behavior in the segment before the last one?


the clean-up flag was used when an SRH was “inserted” underneath the IPv6 header by a transit node. In order to be able to deliver the packet without the SRH you needed an indication for the penultimate segment in order to remove the SRH prior to send the packet to the destination (last segment).

The behavior described in draft-04 is different and consists of the addition of both an outer IPv6 header and an SRH (i.e.: encapsulation instead of insertion). In that context, the PHP behavior (cleanup bit) is no longer needed.

s.


> That is, last segment *always* get the SRH header.
> 
> Thanks,
> Shay
> 
> 
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