Hi Ting

From: spring [mailto:[email protected]] On Behalf Of [email protected]
Sent: Thursday, March 12, 2015 3:03 PM
To: [email protected]
Cc: [email protected]; spring; Stefano Previdi (sprevidi); Peter Psenak (ppsenak)
Subject: [spring] 答复: Re: New Version Notification for 
draft-lw-spring-sid-allocation-01.txt


Hi Rabah,

If the nexthop learnt from the mapping message is the nexthop to the prefix of 
non SR node,
as shown in the figure:
[cid:[email protected]]
The SRMS allocates a SID label 105 to a non SR node LR5,
SR1 learns the message, and the nexthop of SR1 to LR5 is to R4,
SR4 and LR5 is a normal IGP adjancency without label.
When SR1 sending out a packet with a top label 105, the nexthop is to R4,
R4 receives the mpls packet, but it doesn’t have a label forwarding entry, it 
will drop the packet.

[Xiaohu] In fact, R4 could also tunnel the received MPLS packet to LR5 via an 
IP-based tunnel. For more details, please see the approach as described in 
(https://tools.ietf.org/html/draft-xu-spring-islands-connection-over-ip-03).

Best regards,
Xiaohu

Best Regards.
Ting

"spring" <[email protected]<mailto:[email protected]>> 写于 
2015-03-11 18:08:02:

> >Hi, Please see inline[Rabah]
>
> De : [email protected]<mailto:[email protected]> 
> [mailto:[email protected]]
> Envoyé : mercredi 11 mars 2015 10:33
> À : GUEDREZ Rabah IMT/OLN; Peter Psenak (ppsenak); Stefano Previdi (sprevidi)
> Cc : [email protected]<mailto:[email protected]>; spring
> Objet : Re: [spring] New Version Notification for draft-lw-spring-
> sid-allocation-01.txt
>
>
> Hi rabah,peter,stefano,
>
> Thanks for your reviews and comments. The SID allocation proposal is used to
> solve the automatic SID configuration based on the operator's
> requirment of zero configuration for the nodes.
> It includes the following differences with SRMS:
>
> 1.  It has a mechanism to ensure the uniqueness of SID allocation.
> When two or more SRMNs(SR management nodes described in this draft)
> allocate different SIDs to the same prefix,
> we provide a method for the SR nodes to choose one of the SID in theproposal.
>
> 2.  The SRMN only allocates SID to SR node in this draft.
> I wonder there may be some problem if SRMS can allocates SID to non-
> SR node and SR node.
>
> For example, the SRMS is in charge of mapping a SID( SID A) to a non SR node(
> node A)originally,
> and then SRMS floods the mapping message to SR domain, when a SR
> node(node B) receives  the message,
> node B learns an entry of SID A with a nexthop, where  the nexthop
> is the shortest path to SRMS but not to node A.
> Of course the SRMS can be used to allocate a SID(SID C)to a SR
> node(node C),
> when SR node B learns  this message , it still learns the nexthop is
> the shortest path to SRMS,
> and in this case,the nexthop should be to node C.
> >[Rabah]  No this not true upon the reception of  the mapping SID-A
> prefix Z by any SR-Node , the node IGP-SPF will match the SID A
> prefix with its routing table and calculate
>   the shortest path(exit interface) to that prefix and install an
> entry in the NHFE( Next Hop Label   Forwarding Entry).
>
>
> In this proposal, the nexthop is to SR node C.
>
> 3.  In the allocation TLV described in this draft, it can carry
> other SR related configuration such as algorithm, MT number,
> and in a TLV, it can carry one or more ip addresses, no matter the
> addresses are consecutive or inconsecutive.
>
> Best Regards.
> Ting
>
> "spring" <[email protected]<mailto:[email protected]>> 写于 
> 2015-03-10 21:49:49:
>
> > The mapping server is attended to bind prefixes and SID of  non
> > SPRING nodes, not to configure a SPRING node see https://tools.ietf.
> > org/html/draft-filsfils-spring-segment-routing-ldp-interop-02#section-4.2
> >
> > Configuring SPRING nodes can be done manually or via a centralized entity,
> > The centralized entity can be an SDN controller or an extended
> > mapping server, configs can be pushed using OpenFlow or NETCONFIG /YANG see
> > https://tools.ietf.org/id/draft-litkowski-spring-sr-yang-00.txt
> >
> > In my opinion we should work on the process of configuring SPRING
> > nodes, the architecture(SR-client and SR-controller) and defining
> > the minimum configs for a node to function properly.
> >
> > Nether the proposed draft nor the section on the mapping server
> > addressed those requirements.
> >
> > There are two types of configurations that need to be pushed to
> > SPRING nodes  : Required and Optional
> > Required configs : are all the information that has global
> > signification like node-SID, anycast-SID,++ ..., or when decided to
> > use the same SRGB on all the SPRING nodes, those config must be done
> > manually or pushed from centralized entity.
> > Optional configs : all the decision that can be made locally by the
> > "SR-client"  like assigning Adj-SIDs to the node interfaces.
> >
> >
> > -----Message d'origine-----
> > De : spring [mailto:[email protected]] De la part de Stefano
> > Previdi (sprevidi)
> > Envoyé : mardi 10 mars 2015 13:07
> > À : Peter Psenak (ppsenak)
> > Cc : [email protected]<mailto:[email protected]>; 
> > <[email protected]<mailto:[email protected]>>
> > Objet : Re: [spring] New Version Notification for draft-lw-spring-
> > sid-allocation-01.txt
> >
> > I agree. We already have interop tests done on the SRMS so what is
> > the real added value of another proposal ?
> >
> > s.
> >
> >
> > On Mar 10, 2015, at 12:46 PM, Peter Psenak 
> > <[email protected]<mailto:[email protected]>> wrote:
> >
> > > Ting,
> > >
> > > there is a concept of SR Mapping Server, which can be used to
> > advertise SIDs for prefixes from the central place.
> > >
> > > draft-ietf-ospf-segment-routing-extensions defines the OSPF
> > Extended Prefix Range TLV in section 4 which is used to advertise
> > the SID mappings by SRMS. Similarly ISIS SR drafts defines a similar
> > mechanism in ISIS. There are already implementations that support SRMS.
> > >
> > > What you defined in your draft looks very similar to SRMS and we
> > definitely do not need two different ways to achieve the same goal.
> > >
> > > regards,
> > > Peter
> > >
> > > On 3/10/15 07:02 , [email protected]<mailto:[email protected]> 
> > > wrote:
> > >>
> > >> Hi all,
> > >>
> > >> New version of SID Allocation has been published and description has
> > >> been revised according to comments from the mailing list.
> > >> Comments are welcome and discussions in Dallas are expected.
> > >>
> > >> Best Regards.
> > >> Ting
> > >> ----- 转发人 廖婷038768/user/zte_ltd 时间 2015-03-10 08:48 -----
> > >>
> > >> [email protected]<mailto:[email protected]> 写于 2015-03-09 
> > >> 14:39:17:
> > >>
> > >> >
> > >> > A new version of I-D, draft-lw-spring-sid-allocation-01.txt
> > >> > has been successfully submitted by Fangwei Hu and posted to the
> > >> > IETF repository.
> > >> >
> > >> > Name:      draft-lw-spring-sid-allocation
> > >> > Revision:   01
> > >> > Title:      SPRING SID Allocation
> > >> > Document date:   2015-03-08
> > >> > Group:      Individual Submission
> > >> > Pages:      12
> > >> > URL:            http://www.ietf.org/internet-drafts/draft-lw-spring-
> > >> > sid-allocation-01.txt
> > >> > Status:         https://datatracker.ietf.org/doc/draft-lw-spring-
> > >> > sid-allocation/
> > >> > Htmlized:
> > >> http://tools.ietf.org/html/draft-lw-spring-sid-allocation-01
> > >> > Diff:           http://www.ietf.org/rfcdiff?url2=draft-lw-spring-
> > >> > sid-allocation-01
> > >> >
> > >> > Abstract:
> > >> >    Segment Routing (SR) allows for a flexible definition of end-to-end
> > >> >    paths within IGP topologies by encoding paths as sequences of
> > >> >    topological sub-paths, called "segments".  These segments are
> > >> >    advertised by the link-state routing protocols (IS-IS and
> OSPF).  And
> > >> >    a segment is identified by a Segment Routing ID (SID).
> This document
> > >> >    proposes a method to reduce the SID configuration in a SR domain.
> > >> >    Only the selected SR nodes which named Segment Routing Management
> > >> >    Nodes (SRMNs) are configured by NMS, while other SRs in the domain
> > >> >    need zero-SR-configuration.
> > >> >
> > >> >
> > >> >
> > >> >
> > >> > Please note that it may take a couple of minutes from the time of
> > >> submission
> > >> > until the htmlized version and diff are available at tools.ietf.org.
> > >> >
> > >> > The IETF Secretariat
> > >> >
> > >>
> > >>
> > >> _______________________________________________
> > >> spring mailing list
> > >> [email protected]<mailto:[email protected]>
> > >> https://www.ietf.org/mailman/listinfo/spring
> > >>
> > >
> > > _______________________________________________
> > > spring mailing list
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> >
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