> -----邮件原件----- > 发件人: [email protected] [mailto:[email protected]] 代表 Robert Raszuk > 发送时间: 2014年3月28日 17:49 > 收件人: Xuxiaohu > 抄送: Yakov Rekhter; [email protected]; Alvaro Retana, (aretana) > 主题: Re: [spring] WG Adoption Call for > draft-martin-spring-segment-routing-ipv6-use-cases > > Hi Xu, > > Today MPLS over GRE support in most implementations I am familiar with has > been supported for applications using MPLS labels as demux to VRFs (example > L2 or L3 VPNs).
MPLS label can also be used to indicate an outgoing interface. Here a GRE tunnel interface can be looked as an outgoing interface. Best regards, Xiaohu > It is not directly obvious that one can claim support for transport MPLS as > SID > over GRE on existing deployed hardware without requirement to change existing > data plane. I mean of course line rate support in line cards rather then > punting it > to slow path. > After all the switching path needs to support following sequence of operation: > > - Decapsulation of GRE header > - POP > - Lookup subsequent MPLS label as SID in global table > - Encapsulation in GRE + MAC rewrite > > Clearly software upgrade is needed anyway to support SR, but I think you are > making a claim that v6 data plane support will be much harder then the above. > > I think the answer really depends on the particular hardware used. > > Regards, > R. > > > On Fri, Mar 28, 2014 at 10:30 AM, Xuxiaohu <[email protected]> wrote: > > > > > >> -----邮件原件----- > >> 发件人: spring [mailto:[email protected]] 代表 Robert Raszuk > >> 发送时间: 2014年3月28日 16:38 > >> 收件人: Xuxiaohu > >> 抄送: Yakov Rekhter; [email protected]; Alvaro Retana, (aretana) > >> 主题: Re: [spring] WG Adoption Call for > >> draft-martin-spring-segment-routing-ipv6-use-cases > >> > >> Hi Xu, > >> > >> Sure you could. You could do a lot of other things as well. > >> > >> But what does this buy you if you already have dual stack network > >> which most operators already do for years ? > > > > Even you already have a dual stack or IPv6 network, it doesn't mean you can > run IPv6-SR directly on it w/o any change to the IPv6 data plane. IMHO, the > IPv6-SR approach may be suitable for you to achieve the goal that you have > mentioned when those 4 out of those 1000 nodes have been successfully > upgraded to support IPv6-SR while the approach of combining MPLS-SR and > MPLS-over-GRE could still be considered as a viable way (w/o any change to the > data plane) before the above assumption becomes a reality. > > > > Best regards, > > Xiaohu > > > >> For clarity I do not consider as sufficient reason fear from one > >> going into anaphylactic shock at the mention of IPv6 as a valid one. > >> > >> Cheers, > >> R. > >> > >> > >> On Fri, Mar 28, 2014 at 3:08 AM, Xuxiaohu <[email protected]> wrote: > >> > Hi Robert, > >> > > >> > > >> > > >> > I think Yakov’s point could be interpreted as “you can use MPLS-SR > >> > in conjunction with MPLS-over-GRE to realize the goal that you have > >> > mentioned, i.e., only those 4 out of those 1000 nodes need to > >> > support > >> segment routing. > >> > None of the transit nodes needs to be SR aware”. For more details, > >> > please see > >> > http://tools.ietf.org/html/draft-xu-spring-islands-connection-over- > >> > ip and > >> > http://www.ietf.org/proceedings/89/slides/slides-89-spring-0.pptx > >> > > >> > > >> > > >> > Best regards, > >> > > >> > Xiaohu > >> > > >> > > >> > > >> > 发件人: spring [mailto:[email protected]] 代表 Robert Raszuk > >> > 发送时间: 2014年3月27日 23:47 > >> > 收件人: Yakov Rekhter > >> > 抄送: Alvaro Retana, (aretana); [email protected] > >> > 主题: Re: [spring] WG Adoption Call for > >> > draft-martin-spring-segment-routing-ipv6-use-cases > >> > > >> > > >> > > >> > Yakov, > >> > > >> > The topic here is traffic controll and traffic steering. In MPLS to > >> > the best of my knowledge the only tool to accomplish that is MPLS TE. > >> > > >> > That in turn requires RSVP-TE and pretty heavy IGP extensions. > >> > > >> > I am not aware of any deployments of the above MPLS control planes > >> > over GRE nor I am aware of using those when only subset of nodes in > >> > your domain supports required extensions. > >> > > >> > If however you are pointing out that to replace LDP one can use GRE > >> > I completly agree. > >> > > >> > Thx, > >> > R. > >> > > >> > On Mar 27, 2014 4:27 PM, "Yakov Rekhter" <[email protected]> wrote: > >> > > >> > Robert, > >> > > >> >> Hi Yakov, > >> >> > >> >> > The above assumes that the already available technology, MPLS, > >> >> > "may not be available or deployable for lack of support on > >> >> > network elements", yet a brand new technology, a new IPv6 > >> >> > Segment Routing header, will be available, deployable, and > >> >> > supported on network elements. The authors should elaborate on what > makes them think so. > >> >> > >> >> Let's observe that in order to encapsulate traffic in MPLS in 1000 > >> >> node network and steer it north and south 1000 nodes need to be > >> >> able to support MPLS (or for that matter RSVP-TE and IGP > >> >> extensions - let's leave aside inter-area problems). > >> >> > >> >> Contrary if the desire is to steer traffic via north and south > >> >> nodes from given ingress node to egress node only those 4 out of > >> >> those 1000 nodes need to support segment routing. Non of the > >> >> transit nodes needs to be SR aware. > >> > > >> > The ability to carry MPLS over transit nodes that are not MPLS > >> > aware is an already solved problem - it is called MPLS-over-GRE > >> > (rfc4023). > >> > Implemented by multiple vendors. Known to be interoperable. > >> > > >> > Yakov. > >> > > >> > _______________________________________________ > >> > spring mailing list > >> > [email protected] > >> > https://www.ietf.org/mailman/listinfo/spring > >> > > >> > > >> > _______________________________________________ > >> > spring mailing list > >> > [email protected] > >> > https://www.ietf.org/mailman/listinfo/spring > >> > > >> > >> _______________________________________________ > >> spring mailing list > >> [email protected] > >> https://www.ietf.org/mailman/listinfo/spring > > _______________________________________________ > > spring mailing list > > [email protected] > > https://www.ietf.org/mailman/listinfo/spring _______________________________________________ spring mailing list [email protected] https://www.ietf.org/mailman/listinfo/spring
