Re: [spring] Question on draft-ietf-spring-srv6-network-programming-12

[Sander Steffann <[e-mail]>]

Hi,

>>    Having said that, the text about motivating PSP reads:
>>         PSP allows, for example, for an egress PE to receive a packet
>>         with a segment in the DA of the outer header without any need to
>>         process the	SRH.
>>    is a very weak and confusing explanation.  Given that 8200 requires
>>    nodes to be able to ignore any routing header with SL=0, the text as
>>    written seems to be without benefit.
> 
> Joel, how do you know whether you can ignore a routing header?
> I believe that the only option is for the router to process the routing header to check whether the Segments Left value is equal to zero.
> PSP avoids any routing header processing at the egress PE, as the quoted text above states. Hence the benefit.

What benefit?
Sander

PS:

Just because PSP removed a routing header doesn't mean the egress PE doesn't have to look for any remaining routing headers.

From 8200: "Each extension header should occur at most once…".
That is a should, not a must

And: "IPv6 nodes must accept and attempt to process extension headers in any order and occurring any number of times in the same packet…"
That is a must, not a should.