I suggest you read the following blog post by Yakov (http://opencontrail.org/why-contrail-is-using-bgpmpls/).
> -----邮件原件----- > 发件人: Henderickx, Wim (Wim) [mailto:[email protected]] > 发送时间: 2013年11月25日 15:27 > 收件人: Xuxiaohu; [email protected] > 抄送: [email protected] > 主题: Re: 答复: 答复: New Version Notification for > draft-xu-l3vpn-virtual-subnet-02.txt > > There are easier ways to do this which don’t required data-plane changes. > https://tools.ietf.org/html/draft-sajassi-l2vpn-evpn-inter-subnet-forwardin > g-02 > > On 25/11/13 07:40, "Xuxiaohu" <[email protected]> wrote: > > > > > > >> -----邮件原件----- > >> 发件人: Henderickx, Wim (Wim) > [mailto:[email protected]] > >> 发送时间: 2013年11月25日 14:29 > >> 收件人: Xuxiaohu; [email protected] > >> 抄送: [email protected] > >> 主题: Re: 答复: New Version Notification for > >> draft-xu-l3vpn-virtual-subnet-02.txt > >> > >> It is not about TTL 1, no TTL decrement should happen for > >>intra-subnet forwarding at all On top you need to modify the > >>data-plane to achieve this, since it now needs to find out if it is > >>intra or inter subnet where current PE(s) don’t have to do this. > > > >Sure, it needs some change to the implementation of PE routers. That's > >why we need a draft to specify the implementation requirements. > > > >> On 25/11/13 07:22, "Xuxiaohu" <[email protected]> wrote: > >> > >> >Wim, > >> > > >> >It said clearly "if the source and destination addresses of a packet > >> >whose TTL is set to 1 belong to the same extended subnet, both > >> >ingress and egress PE routers MUST NOT decrement the TTL of such > >> >packet." Did you doubt that the PE routers could know whether the > >> >source and destination address belong to the same extended subnet? > >> > > >> >Xiaohu > >> > > >> >> -----邮件原件----- > >> >> 发件人: Henderickx, Wim (Wim) > >> [mailto:[email protected]] > >> >> 发送时间: 2013年11月25日 14:08 > >> >> 收件人: Xuxiaohu; [email protected] > >> >> 抄送: [email protected] > >> >> 主题: Re: New Version Notification for > >> >>draft-xu-l3vpn-virtual-subnet-02.txt > >> >> > >> >> On the TTL issue I believe this is not addressing the issue. We > >> >>can say don’t decrement but when and how will the PE(s) do or don’t. > >> >> > >> >> On 25/11/13 03:22, "Xuxiaohu" <[email protected]> wrote: > >> >> > >> >> >Hi all, > >> >> > > >> >> >Major changes since the -01 version include: > >> >> > > >> >> >1) add a section about TTL consideration; > >> >> >2) remove the section of PE Router FIB Reduction; > >> >> >3) remove the section of PE Router RIB Reduction; > >> >> > > >> >> >Any further comments are welcome. BTW, the removed sections as > >> >> >mentioned above would be described in separate docs. > >> >> > > >> >> >Best regards, > >> >> >Xiaohu > >> >> > > >> >> >> -----邮件原件----- > >> >> >> 发件人: [email protected] [mailto:[email protected]] > >> >> >> 发送时间: 2013年11月25日 10:10 > >> >> >> 收件人: Brendan Fee; Susan Hares; Fan Yongbing; Xuxiaohu; > >> >> >>Xuxiaohu; Christian Jacquenet; Truman Boyes; Yongbing Fan > >> >> >> 主题: New Version Notification for > >> >> >>draft-xu-l3vpn-virtual-subnet-02.txt > >> >> >> > >> >> >> > >> >> >> A new version of I-D, draft-xu-l3vpn-virtual-subnet-02.txt > >> >> >> has been successfully submitted by Xiaohu Xu and posted to the > >> >> >>IETF repository. > >> >> >> > >> >> >> Filename: draft-xu-l3vpn-virtual-subnet > >> >> >> Revision: 02 > >> >> >> Title: Virtual Subnet: A L3VPN-based Subnet Extension > >> >> >> Solution > >> >> >> Creation date: 2013-11-25 > >> >> >> Group: Individual Submission > >> >> >> Number of pages: 13 > >> >> >> URL: > >> >> >> > >> >>http://www.ietf.org/internet-drafts/draft-xu-l3vpn-virtual-subnet-0 > >> >>2.t > >> >>xt > >> >> >> Status: > >> >> >>http://datatracker.ietf.org/doc/draft-xu-l3vpn-virtual-subnet > >> >> >> Htmlized: > >> >> >>http://tools.ietf.org/html/draft-xu-l3vpn-virtual-subnet-02 > >> >> >> Diff: > >> >> >> > >> >> >>http://www.ietf.org/rfcdiff?url2=draft-xu-l3vpn-virtual-subnet-0 > >> >> >>2 > >> >> >> > >> >> >> Abstract: > >> >> >> This document describes a Layer3 Virtual Private Network > >>(L3VPN)- > >> >> >> based subnet extension solution referred to as Virtual > >> >> >> Subnet, > >> >>which > >> >> >> can be used as a kind of Layer3 network virtualization overlay > >> >> >> approach for data center interconnect. > >> >> >> > >> >> >> > >> >> >> > >> >> >> > >> >> >> 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 > >> >> > > >> > > >
