Hi Ron, I’m glad we read that the same.

As usual for SRv6, the SR source needs to decide how to build the IPv6 
extension header chain. With current text, when extension headers are required 
to be processed at the ultimate segment, the SR source would need to add an SRH.

Would you agree?

The pseudocode could be modified such that the SR source adds an SRH only when 
it wants a dest-opt header to be processed at each segment endpoint. Section 
4.1.1 would state the pseudocode is invoked when processing any header type 
other than HBH or dest-opt (vs just upper layer header).

Darren


On 2021-11-16, 1:14 PM, "Ron Bonica" <[email protected]> 
wrote:

Hi Darren,

That’s my reading, too. But this leads us to additional questions:

-         How do we encode destination options that need to be processed at the 
SR Path egress node only?

-         How do we encode the Fragment Option?

-         How do we encode the ESP option?
In these cases, do we need an SRH to indicate that the extension headers that 
follow it are to be processed by the SR path egress node only? Would that SRH 
carry any routing information at all?

                                                                                
        Ron




Juniper Business Use Only
From: Darren Dukes (ddukes) <[email protected]>
Sent: Tuesday, November 16, 2021 8:31 AM
To: Ron Bonica <[email protected]>; [email protected]; [email protected]
Subject: Re: uSID and destination options

[External Email. Be cautious of content]

Hi Ron, my read of section 4.1.1 of the draft is the dest opt in your example 
packet would be processed at every segment endpoint.

Darren
________________________________
From: spring <[email protected]<mailto:[email protected]>> on 
behalf of Ron Bonica 
<[email protected]<mailto:[email protected]>>
Sent: Monday, November 15, 2021 2:12 PM
To: [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Subject: [spring] uSID and destination options

C-SID authors,

Consider an SRv6 packet that contains:


·         An outer IPv6 header

·         A Destination Options Header

·         IPv4 payload

The packet does not contain an SRH. However, the Destination Address field  in 
the outer IPv6 header contains a C-SID container and the C-SID container 
contains two or more C-SIDs.

Where are the destination options processed? The following are possible answers 
to this question:


·         At every segment endpoint node

·         At the SR path egress node

                                                     Ron



Juniper Business Use Only
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