Hi Stewart, I add following points: 1. since the protection is based on multi-homing or dual-homing scenarios, according to my experience on the network deployment design of carriers, they always use the devices with similar capacity for the multi-homed PEs. That is, the hardware and label range could be matching. 2. According to the general L3VPN deployment of carriers, they must guarantee the scalability. That is, they will not use out the label range as many as possible. Instead they will try to save the label range. The possible way includes 1) Only set up LSP for host IP address(/32). There are not too many host IP address in a network. 2) For L3VPN, they use label allocation per instance instead of label allocation per prefix. For one VPN, there only uses 2-3 label per VPN. By possible ways, there can save enough label according to existing L3VPN deployment scenario. It is not difficult to get a common label range for the multi-homed PEs. 3. According to 1/2, the common label range can be found for the multi-homed PEs. With ICCP extensions to coordinate the label allocation between PEs, the label sharing can work. 4. The above point is for the existing L3VPN scenarios. For the emerging large scale L3VPN deployment scenarios, it just begins to discuss in IETF. Maybe it is necessary to expand the existing MPLS label range which has been proposed in draft-renwei-mpls-big-label-00 and draft-li-mpls-mega-label-00. I think these topics are just in the initial phase in IETF.
Thanks, Robin -----邮件原件----- 发件人: [email protected] [mailto:[email protected]] 代表 Mingui Zhang 发送时间: 2013年11月18日 17:34 收件人: [email protected]; Jakob Heitz; [email protected] 主题: RE: Why we consider the method of "label sharing for fast PE protection" Hi Stewart, Operators can configure the PEs in an RG to reserve the same label range for sharing. With the ICCP connection established between the primary and backup PE, the primary PE can mandate the sharing label range out of the intersection of the unused label space. Thanks, Mingui >-----Original Message----- >From: Stewart Bryant [mailto:[email protected]] >Sent: Thursday, November 14, 2013 9:52 PM >To: Jakob Heitz; Mingui Zhang; [email protected] >Subject: Re: Why we consider the method of "label sharing for fast PE >protection" > >Isn't the normal problem that the two systems will be independently >allocating labels from their default label table, possibly with >different hardware base and range, so there may not be a common label >available that can be allocated by both. > >- Stewart > >On 07/11/2013 21:50, Jakob Heitz wrote: > > > Several people at the mike asked this question: > How do you make sure that the PEs allocate the same label? > > This needs to be part of the document, because it is quite important. > If an external entity allocates the labels, the protocol > between the PEs and that entity needs to be standardized. > Since this is a feature that provides redundancy, the > label allocating entity also needs to be backed up by a > redundant entity. The protocol between the redundant > label allocators needs to be standardized. > > > > -- > > Jakob Heitz. > >________________________________ > > From: [email protected] [[email protected]] on behalf of >Mingui Zhang [[email protected]] > Sent: Thursday, 07 November 2013 11:40 AM > To: [email protected] > Subject: Why we consider the method of "label sharing for fast PE >protection" > > > > Hi, > > As a choice of fast PE protection, > > 1. This solution is simple and light-weight. We need not introduce the >complex context label table in PE routers. So label table need not be >stored repeatedly on RG members. > > > 2. Also, it's easy to be deployed. It does not bring any change to P >routers (control plane & data plane). It even does not change the data >plane of PE routers. > > > 3. In addition, it does not bear the restriction of "no >penultimate-hop-popping". > > > > Thanks, > Mingui > > > > >-- >For corporate legal information go to: > >http://www.cisco.com/web/about/doing_business/legal/cri/index.html
