MPLS world PSP will help in avoiding one more lookup at egress for VPN cases.

I feel both PSP and USP are not useful in case of SRV6.



Juniper Business Use Only
From: Wang, Weibin (NSB - CN/Shanghai) <weibin.w...@nokia-sbell.com>
Sent: Saturday, October 19, 2019 6:26 AM
To: Rajesh M <mraj...@juniper.net>; Rajesh M 
<mrajesh=40juniper....@dmarc..ietf.org>; Pablo Camarillo (pcamaril) 
<pcama...@cisco.com>; SPRING WG List <spring@ietf.org>
Cc: Srihari Sangli <ssan...@juniper.net>; Shraddha Hegde <shrad...@juniper.net>
Subject: RE: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24

Hi Rajesh:
The answer to your question, I think, had better be provided by Authors of 
NET-PGM, You can also refer to Ron’s email previously one or two days before 
who give some guess, I think it make sense, in addition , also including 
processing-load mitigation in Last hop (egress PE);
Could you Pls explain the benefit of similar behavior in PHP of MPLS world.  I 
think it may be same.

--------------------------------------
Cheers !


WANG Weibin

From: Rajesh M <mraj...@juniper.net<mailto:mraj...@juniper.net>>
Sent: 2019年10月18日 20:18
To: Wang, Weibin (NSB - CN/Shanghai) 
<weibin.w...@nokia-sbell.com<mailto:weibin.w...@nokia-sbell.com>>; Rajesh M 
<mrajesh=40juniper....@dmarc.ietf.org<mailto:mrajesh=40juniper....@dmarc.ietf.org>>;
 Pablo Camarillo (pcamaril) <pcama...@cisco.com<mailto:pcama...@cisco.com>>; 
SPRING WG List <spring@ietf.org<mailto:spring@ietf.org>>
Cc: Srihari Sangli <ssan...@juniper.net<mailto:ssan...@juniper.net>>; Shraddha 
Hegde <shrad...@juniper.net<mailto:shrad...@juniper.net>>
Subject: RE: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24

I was more focused towards END.DT4 SID where behavior you mentioned is possible 
only if we do below optimization in 
https://tools.ietf.org/html/draft-dawra-bess-srv6-services-02<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-dawra-bess-srv6-services-02__;!8WoA6RjC81c!VLXDHwQhv3Ai4Cky1wjCRKLg4MMbWlArh2rC0Srmtc6uKxdGYoSjuGxkKh-cx1pT$>
  section 3.

when the received route is colored with an extended color community 'C' and 
Next-Hop 'N', and the ingress PE has a valid SRv6 Policy (C, N) associated with 
SID list <S1,S2, S3>, then the effective SR Policy is <S1, S2, 
SRv6-Service-SID>.Here if you see
S3 and SRv6-Service-SID both belong to Egress so s3 has been removed.


For you my query is removing only SRH header on PHP router will give what kind 
of advantage ?

Thanks
Rajesh





Juniper Business Use Only
From: spring <spring-boun...@ietf.org<mailto:spring-boun...@ietf.org>> On 
Behalf Of Wang, Weibin (NSB - CN/Shanghai)
Sent: Friday, October 18, 2019 9:26 AM
To: Rajesh M 
<mrajesh=40juniper....@dmarc.ietf.org<mailto:mrajesh=40juniper....@dmarc.ietf.org>>;
 Pablo Camarillo (pcamaril) <pcama...@cisco.com<mailto:pcama...@cisco.com>>; 
SPRING WG List <spring@ietf.org<mailto:spring@ietf.org>>
Cc: Srihari Sangli <ssan...@juniper.net<mailto:ssan...@juniper.net>>; Shraddha 
Hegde <shrad...@juniper.net<mailto:shrad...@juniper.net>>
Subject: Re: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04*page-24__;Iw!8WoA6RjC81c!Xvm3hzUGljwi9nBE2mtVYPtMItbLLS1EMD8VDmp4d3K0OZliIbHVQDKF1Nw-lbbm$>

The value of Segment Left field in SRH begin with 0, so [SL]=0 represent the 
last SID. in this case, when [SL] decrease 1, and the penultimate SRv6 node 
copy IPv6 SID corresponding to [SL]=0 to DA field of IP packet, when enable PSP 
flavor at same time, the penultimate SRv6 node will check the [SL] value, if it 
is 0, then pop SRH, these extra action is pseudocode of PSP. This logic has no 
problem.


--------------------------------------
Cheers !


WANG Weibin

From: spring <spring-boun...@ietf.org<mailto:spring-boun...@ietf.org>> On 
Behalf Of Rajesh M
Sent: 2019年10月18日 6:38
To: Pablo Camarillo (pcamaril) <pcama...@cisco.com<mailto:pcama...@cisco.com>>; 
SPRING WG List <spring@ietf.org<mailto:spring@ietf.org>>
Cc: Srihari Sangli <ssan...@juniper.net<mailto:ssan...@juniper.net>>; Shraddha 
Hegde <shrad...@juniper.net<mailto:shrad...@juniper.net>>
Subject: Re: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04*page-24__;Iw!8WoA6RjC81c!Xvm3hzUGljwi9nBE2mtVYPtMItbLLS1EMD8VDmp4d3K0OZliIbHVQDKF1Nw-lbbm$>

WANG had given below use case : But using existing PSP logic this will not work.
In below at PSP router updated SL will be 1 (since END.DT4 is still there) ,so 
SRH pop won’t happen.



   S14.1.   If (updated SL == 0) {

   S14.2.      Pop the SRH

   S14.3.   }

WANG use case:
“For example in SRv6-based L3VPN service scenario, The ingress PE within 
SRv6-enabled domain can utilize SR-TE policy to enable TE-path function when 
encapsulating and transiting L3VPN traffic, The Ingress PE push on customer 
packets with SID list representing SR-TE policy plus END.DT4 as last SRv6 SID 
in SRH; So I think, each flavor of PSP/USP/USD can be designed to perform in 
related SRv6 endpoint. Imaging the PSP, the penultimate Endpoint can perform 
PSP, e.g. copy the last SID (END.DT4) of SRH to destination field of IPv6 
header and POP the SRH, then forwarding it toward egress PE identified by DA”







Juniper Business Use Only
From: Pablo Camarillo (pcamaril) 
<pcama...@cisco.com<mailto:pcama...@cisco...com>>
Sent: Tuesday, October 15, 2019 10:13 PM
To: Rajesh M <mraj...@juniper.net<mailto:mraj...@juniper.net>>; SPRING WG List 
<spring@ietf.org<mailto:spring@ietf.org>>
Cc: Srihari Sangli <ssan...@juniper.net<mailto:ssan...@juniper.net>>; Shraddha 
Hegde <shrad...@juniper.net<mailto:shrad...@juniper.net>>
Subject: Re: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04*page-24__;Iw!8WoA6RjC81c!Wogoc-HBxWprNFIMxDGoprcCPpEqeSUK6WmLst9CNbljhrh-Ur4yOghFj3kDJQnV$>

Rajesh,

This has already been replied less than one week ago.. Please see:
https://mailarchive.ietf.org/arch/msg/spring/V0ZpjVLSVZxHaBwecXFxqJjlg_c<https://urldefense.com/v3/__https:/mailarchive.ietf.org/arch/msg/spring/V0ZpjVLSVZxHaBwecXFxqJjlg_c__;!8WoA6RjC81c!W8zXtokq31cYlPoLJ6Ip-BlyXApb7JIhuJzRXW3khd_OAByxCvaxs9Jw7HGIr9o9$>
https://mailarchive.ietf.org/arch/msg/spring/WrYzRZC0HKVgBYaYMCQVcTWrfak<https://urldefense.com/v3/__https:/mailarchive.ietf.org/arch/msg/spring/WrYzRZC0HKVgBYaYMCQVcTWrfak__;!8WoA6RjC81c!W8zXtokq31cYlPoLJ6Ip-BlyXApb7JIhuJzRXW3khd_OAByxCvaxs9Jw7P8QaU_7$>

Thanks,
Pablo.


From: spring <spring-boun...@ietf.org<mailto:spring-boun...@ietf.org>> on 
behalf of Rajesh M 
<mrajesh=40juniper....@dmarc.ietf.org<mailto:mrajesh=40juniper....@dmarc.ietf.org>>
Date: Friday, 11 October 2019 at 03:47
To: SPRING WG List <spring@ietf.org<mailto:spring@ietf.org>>
Cc: Srihari Sangli <ssan...@juniper.net<mailto:ssan...@juniper.net>>, Shraddha 
Hegde <shrad...@juniper.net<mailto:shrad...@juniper.net>>
Subject: [spring] 
https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04#page-24<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04*page-24__;Iw!8WoA6RjC81c!Wogoc-HBxWprNFIMxDGoprcCPpEqeSUK6WmLst9CNbljhrh-Ur4yOghFj3kDJQnV$>


Wanted to know the use case where we only POP the SRH ?

4.16.1<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-04*section-4.16.1__;Iw!8WoA6RjC81c!W8zXtokq31cYlPoLJ6Ip-BlyXApb7JIhuJzRXW3khd_OAByxCvaxs9Jw7DAv5v98$>..
  PSP: Penultimate Segment Pop of the SRH

   The SRH processing of the End, End.X and End.T behaviors are

   modified: after the instruction "S14.  Update IPv6 DA with Segment

   List[Segments Left]" is executed, the following instructions must be

   executed as well:



   S14.1.   If (updated SL == 0) {

   S14.2.      Pop the SRH

   S14.3.   }



Juniper Business Use Only
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