RE: [IPv6 SR] Regarding 128 bits IPv6 address in Segment List of SRH

Veerendranatha Reddy Vallem <> Fri, 10 February 2017 06:38 UTC

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From: Veerendranatha Reddy Vallem <>
To: "Stefano Previdi (sprevidi)" <>
Subject: RE: [IPv6 SR] Regarding 128 bits IPv6 address in Segment List of SRH
Thread-Topic: [IPv6 SR] Regarding 128 bits IPv6 address in Segment List of SRH
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Date: Fri, 10 Feb 2017 06:37:48 +0000
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Dear Previdi,
Thanks for your reply. 

As per first version of draft, Adj-SID is also  IPv6 prefix. 

4.2.2.  Adjacency-SID

   The Adjacency-SID identifies a given interface.  In the SR
   architecture a node may advertise one or more Adj-SIDs allocated to a
   given interface so to force the forwarding of the packet (when
   received with that particular Adj-SID) into the interface, regardless
   the routing entry for the packet destination.  The same is defined
   for SR-IPv6: a node may advertise a given IPv6 prefix which is
   associated to the SR semantic of "send out the packet to the
   interface this prefix is allocated to".  Here also, the SID is in
   fact the IPv6 prefix.

As per my understanding  "segment list in SRH is global IPv6 prefixes, If we need to include Adj SID to segment list then Adj-SID is also global IPv6 prefix". 
Please correct me if my understanding is wrong.

Thanks and Regards,

-----Original Message-----
From: Stefano Previdi (sprevidi) [] 
Sent: 09 February 2017 22:41
To: Veerendranatha Reddy Vallem <>
Subject: Re: [IPv6 SR] Regarding 128 bits IPv6 address in Segment List of SRH


the first version of the draft (draft-previdi-6man-segment-routing-header) had a description of Node-SID and Adj-SID. Later, in order to simplify the document, we removed the descriptions and focused the document into the SRH format.

I think it will be helpful to re-introduce a section on the two main SID types (Node, Adjacency). I’m working on an update for the next version.


> On Feb 9, 2017, at 5:02 PM, Veerendranatha Reddy Vallem <> wrote:
> Dear Authors,
> I am requesting your clarification regarding usage of Adj-SID in SRH header