Re: [spring] SRv6 BGP based Overlay Services (draft-ietf-bess-srv6-services-07)

Gyan Mishra <hayabusagsm@gmail.com> Sat, 24 July 2021 06:56 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Sat, 24 Jul 2021 02:56:37 -0400
Message-ID: <CABNhwV2sfTSo4_9h-OVOUTa8W0By_swwhMsOUSnzymndMafWbA@mail.gmail.com>
To: "Aissaoui, Mustapha (Nokia - CA/Ottawa)" <mustapha.aissaoui@nokia.com>
Cc: "Ketan Talaulikar (ketant)" <ketant@cisco.com>, Shraddha Hegde <shraddha@juniper.net>, "bess@ietf.org" <bess@ietf.org>, "draft-ietf-bess-srv6-services@ietf.org" <draft-ietf-bess-srv6-services@ietf.org>, "spring@ietf.org" <spring@ietf.org>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/spring/g8ZawXs_6FDTkKLTRfFXHWWwkTQ>
Subject: Re: [spring] SRv6 BGP based Overlay Services (draft-ietf-bess-srv6-services-07)
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Hi Shraddha

I agree the fallback mechanisms are important to operators but as there are
many complex scenarios related to fallback and some of which include SRv6
to SR-MPLS interworking, I agree that this is important and as such can be
captured in a separate document that defines all the permutations in detail.

As this SRv6 BGP overlay services specification is critical for operators
as it’s in WGLC I think it should proceed to publication.

Kind Regards

Gyan

On Fri, Jul 23, 2021 at 12:40 PM Aissaoui, Mustapha (Nokia - CA/Ottawa) <
mustapha.aissaoui@nokia.com> wrote:

> That is great. Thank you.
>
>
>
> Mustapha.
>
>
>
> *From:* Ketan Talaulikar (ketant) <ketant@cisco.com>
> *Sent:* Friday, July 23, 2021 11:08 AM
> *To:* Aissaoui, Mustapha (Nokia - CA/Ottawa) <mustapha.aissaoui@nokia.com>
> *Cc:* spring@ietf.org; Shraddha Hegde <shraddha@juniper.net>et>;
> bess@ietf.org; draft-ietf-bess-srv6-services@ietf.org
> *Subject:* RE: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> < trimming list to mostly mailers >
>
>
>
> Hi Mustapha,
>
>
>
> I agree.
>
>
>
> Also after seeing Shraddha’s latest email, the coverage and details for
> the fallback mechanisms that she seems to be looking for is quite vast and
> better tackled in a separate document since this one has completed its
> WGLC. Some of those concepts are applicable for MPLS as well and not SRv6
> specific.
>
>
>
> We (authors) will work on some text proposal and get back to the WG next
> week.
>
>
>
> Thanks,
>
> Ketan
>
>
>
> *From:* Aissaoui, Mustapha (Nokia - CA/Ottawa) <
> mustapha.aissaoui@nokia.com>
> *Sent:* 23 July 2021 19:20
> *To:* Ketan Talaulikar (ketant) <ketant@cisco.com>om>; Rajesh M <
> mrajesh@juniper.net>gt;; Rajesh M <mrajesh@juniper.net>et>; Rabadan, Jorge
> (Nokia - US/Mountain View) <jorge.rabadan@nokia.com>om>;
> gdawra.ietf@gmail.com; Clarence Filsfils (cfilsfil) <cfilsfil@cisco.com>om>;
> robert@raszuk.net; bruno.decraene@orange.com
> *Cc:* spring@ietf.org; bgp@ans.net; Srihari Sangli <ssangli@juniper.net>et>;
> Shraddha Hegde <shraddha@juniper.net>et>; bess@ietf.org
> *Subject:* RE: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> Hi Ketan,
>
> I believe it will be worth expanding the text in
> draft-ietf-bess-srv6-services to describe the two types of transport more
> consistently and along the lines of what you wrote below. Also, I would
> propose that we move away from terminology like best-effort service and
> instead just mention shortest path forwarding in base topology or in
> flex-algo topology.
>
>
>
> Mustapha.
>
>
>
> *From:* spring <spring-bounces@ietf.org> *On Behalf Of *Ketan Talaulikar
> (ketant)
> *Sent:* Thursday, July 22, 2021 3:43 AM
> *To:* Rajesh M <mrajesh@juniper.net>et>; Rajesh M <
> mrajesh=40juniper.net@dmarc.ietf.org>gt;; Rabadan, Jorge (Nokia -
> US/Mountain View) <jorge.rabadan@nokia.com>om>; gdawra.ietf@gmail.com;
> Clarence Filsfils (cfilsfil) <cfilsfil@cisco.com>om>; robert@raszuk.net;
> bruno.decraene@orange.com
> *Cc:* spring@ietf.org; bgp@ans.net; Srihari Sangli <ssangli@juniper.net>et>;
> Shraddha Hegde <shraddha@juniper.net>et>; bess@ietf.org
> *Subject:* Re: [spring] SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> Hi Rajesh,
>
>
>
> My apologies for the delay in my response. However, some of my co-authors
> and other WG members have already clarified this point. Let me try to
> summarize.
>
>
>
> The draft covers two SRv6 based mechanisms for the transport of services
> between SRv6 PEs. (1) using SR Policy based steering (i.e. for service
> routes with Color Extended Communities) using the H.encap construct along
> with a list of SRv6 segments  and the other (2) using H.encap with just the
> SRv6 Service SID in the IPv6 DA.
>
>
>
> As mentioned in the draft, it is required to verify the reachability of
> the SRv6 Service SID before the mechanism (2) can be used. This is an
> explicit clarification for verification of reachability. In an MPLS-VPN
> scenario, if the egress PE NH’s IP route is reachable at the ingress PE but
> without an MPLS label, such a path cannot be used. This is semantically
> similar.
>
>
>
> The mechanism (1) is different since the routing to the egress PE is via
> SR Policy and hence the requirement for verification of reachability of the
> SRv6 Service SID is not there.
>
>
>
> There is no mandate for the setting of the NH since that is left to
> deployment design.
>
>
>
> I hope this helps in addition to the various clarifications already
> provided by others.
>
>
>
> Thanks,
>
> Ketan
>
>
>
> *From:* Rajesh M <mrajesh@juniper.net>
> *Sent:* 22 July 2021 12:09
> *To:* Rajesh M <mrajesh=40juniper.net@dmarc.ietf.org>rg>; Rabadan, Jorge
> (Nokia - US/Mountain View) <jorge.rabadan@nokia.com>om>; Ketan Talaulikar
> (ketant) <ketant@cisco.com>om>; gdawra.ietf@gmail.com; Clarence Filsfils
> (cfilsfil) <cfilsfil@cisco.com>om>; robert@raszuk.net;
> bruno.decraene@orange.com
> *Cc:* spring@ietf.org; bgp@ans.net; Shraddha Hegde <shraddha@juniper.net>et>;
> bess@ietf.org; Srihari Sangli <ssangli@juniper.net>
> *Subject:* RE: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> Could Authors respond to this ?
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Rajesh M <mrajesh=40juniper.net@dmarc.ietf.org>
> *Sent:* Monday, July 19, 2021 7:28 PM
> *To:* Rabadan, Jorge (Nokia - US/Mountain View) <jorge.rabadan@nokia.com>om>;
> Rajesh M <mrajesh@juniper.net>et>; Ketan Talaulikar (ketant) <
> ketant@cisco.com>gt;; gdawra.ietf@gmail.com; Clarence Filsfils (cfilsfil) <
> cfilsfil@cisco.com>gt;; robert@raszuk.net; bruno.decraene@orange.com
> *Cc:* spring@ietf.org; bgp@ans.net; Shraddha Hegde <shraddha@juniper.net>et>;
> bess@ietf.org; Srihari Sangli <ssangli@juniper.net>
> *Subject:* RE: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> *[External Email. Be cautious of content]*
>
>
>
> Hi All,
>
>
>
> For best effort service, flex algo – Resolve SRv6 Service SID for
> forwarding.
>
> For SR-TE, CAR/CT - Resolve BGP next hop for forwarding.
>
>
>
> There is no unification here, it’s better to unify.
>
> Any other solution is OK.
>
>
>
> Thanks
>
> Rajesh
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* Rabadan, Jorge (Nokia - US/Mountain View) <jorge.rabadan@nokia.com>
>
> *Sent:* Monday, July 19, 2021 7:17 PM
> *To:* Rajesh M <mrajesh@juniper.net>et>; Rajesh M <
> mrajesh=40juniper.net@dmarc.ietf.org>gt;; Ketan Talaulikar (ketant) <
> ketant@cisco.com>gt;; gdawra.ietf@gmail.com; Clarence Filsfils (cfilsfil) <
> cfilsfil@cisco.com>gt;; robert@raszuk.net; bruno.decraene@orange.com
> *Cc:* spring@ietf.org; bgp@ans.net; Shraddha Hegde <shraddha@juniper.net>et>;
> bess@ietf.org; Srihari Sangli <ssangli@juniper.net>
> *Subject:* Re: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> *[External Email. Be cautious of content]*
>
>
>
> Hi Rajesh,
>
>
>
> The draft is written so that the next-hop address MAY be covered by the
> locator, but there are cases in which the next-hop address is not part of
> the locator prefix, and there are implementations already allowing that, so
> I don’t agree the document should mandate what you are suggesting.
>
>
>
> Thanks.
>
> Jorge
>
>
>
> *From: *Rajesh M <mrajesh@juniper.net>
> *Date: *Monday, July 19, 2021 at 3:24 PM
> *To: *Rajesh M <mrajesh=40juniper.net@dmarc.ietf.org>rg>, Ketan Talaulikar
> (ketant) <ketant@cisco.com>om>, gdawra.ietf@gmail.com <gdawra.ietf@gmail.com>om>,
> Clarence Filsfils (cfilsfil) <cfilsfil@cisco.com>om>, robert@raszuk.net <
> robert@raszuk.net>gt;, bruno.decraene@orange.com <bruno.decraene@orange.com>om>,
> Rabadan, Jorge (Nokia - US/Mountain View) <jorge.rabadan@nokia.com>
> *Cc: *spring@ietf.org <spring@ietf.org>rg>, bgp@ans.net <bgp@ans.net>et>,
> Shraddha Hegde <shraddha@juniper.net>et>, bess@ietf.org <bess@ietf.org>rg>,
> Srihari Sangli <ssangli@juniper.net>
> *Subject: *RE: SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
> Hi Authors,
>
>
>
> Please respond.
>
>
>
> Thanks
>
> Rajesh
>
>
>
>
>
> Juniper Business Use Only
>
> *From:* spring <spring-bounces@ietf.org> *On Behalf Of *Rajesh M
> *Sent:* Thursday, July 15, 2021 4:36 PM
> *To:* Ketan Talaulikar (ketant) <ketant@cisco.com>om>; gdawra.ietf@gmail.com;
> Clarence Filsfils (cfilsfil) <cfilsfil@cisco.com>om>; robert@raszuk.net;
> bruno.decraene@orange.com; jorge.rabadan@nokia.com
> *Cc:* spring@ietf.org; bgp@ans.net; Shraddha Hegde <shraddha@juniper.net>et>;
> bess@ietf.org
> *Subject:* [spring] SRv6 BGP based Overlay Services
> (draft-ietf-bess-srv6-services-07)
>
>
>
> *[External Email. Be cautious of content]*
>
>
>
> Hi All,
>
>
>
> As per this draft, this is how resolution must work.
>
>
>
> 1)For Non Intent service Route:
>
> if BGP next hop is not reachable return.
>
> Resolve SRv6 Service SID for forwarding.
>
>
>
> 2)For Intent service Route (IGP Flex-Algo first then BGP CAR then SR
> Policy):
>
> BGP next hop is not reachable return.
>
> Resolve SRv6 Service SID for forwarding(To find IGP flex algo).if
> successfully resolves then return.
>
> Resolve BGP next hop for forwarding (in case above is not success).
>
>
>
>
>
> *Using Service SID (overlay),for resolution is definitely not recommended.*
>
>
>
> *Instead in case of srv6, we always resolve on BGP nexthop. This will be
> in line with BGP legacy.*
>
> *In case of best effort/flex algo we must mandate user to set
> corresponding locator as BGP nexthop for srv6 routes.*
>
> *I think this is a reasonable mandate.*
>
>
>
> Thanks
>
> Rajesh
>
>
>
> Juniper Business Use Only
> _______________________________________________
> spring mailing list
> spring@ietf.org
> https://www.ietf.org/mailman/listinfo/spring
>
-- 

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *

*Email gyan.s.mishra@verizon.com <gyan.s.mishra@verizon.com>*



*M 301 502-1347*