Peter, Please see inline.
> -----Original Message----- > From: Peter Psenak [mailto:[email protected]] > Sent: Tuesday, November 23, 2010 2:14 PM > To: Jeffrey (Zhaohui) Zhang > Cc: [email protected] > Subject: Re: [OSPF] OSPF Hybrid Broadcast and P2MP Interface Type > > Hi Jeffrey, > > please see inline: > > On 23.11.2010 19:29, Jeffrey (Zhaohui) Zhang wrote: > > Peter, > > > > I think I understand the potential issue you mentioned, but > not quite clear about your solution. > > > > The draft mentions that the metrics could be dynamically > learned if the underlying network support it (in that case > the l2 and l3 should match). However that is outside the > scope the draft, which assumes that the metrics is obtained > by some means. Indeed if it is statically configured then the > operator needs to be careful. > > dynamically updating L3 metrics based on the L2 topology is a > problem of > it own. The consequence is that L2 network changes that > mostly used to > be hidden to the L3 now becomes propagated to the L3 network. If L2 network changes lead to L3 metric change, then it should not be hidden though? I agree that the propogation of the changes needs to be rate limited, and a balance needs to be kept between routing stability and routing optimization. Also about your original concern with l2/l3 mismatch - I don't think it is unique with this proposal. When you assign an interface metric for a regular interface (or neighbor in p2mp case) you also need to make sure that the metric reflects the l2 characteristics. > > > > > You mentioned creating p2p l2 connections. Does that mean > there will be correponding l3 p2p interfaces? If yes isn't it > no longer a bcast/p2mp hybrid? If not can you elaborate? > > yes, some form of a sub-interface using the VLAN technology. That is > typically a p2p connection between the two OSPF speakers. The very purpose of the proposal is to use the hybrid interface type to avoid the inefficiency with p2p/p2mp links when it comes to adjaceny and db synchronization, while being able to advertise different metrics per neighbor. Thanks. Jeffrey > > thanks, > Peter > > > > Thanks. > > Jeffrey > > > >> -----Original Message----- > >> From: Peter Psenak [mailto:[email protected]] > >> Sent: Tuesday, November 23, 2010 1:11 PM > >> To: Jeffrey (Zhaohui) Zhang > >> Cc: [email protected] > >> Subject: Re: [OSPF] OSPF Hybrid Broadcast and P2MP Interface Type > >> > >> Hi Jeffrey, > >> > >> one potential issue with this approach is the possible suboptimal > >> traffic path if the L3 p2p topology created as you described do not > >> match the L2 forwarding topology. With large L2 domains it > may be be > >> nontrivial to assign L3 metric correctly so that the L2/L3 > >> forwarding match. > >> > >> One possible method to address the problem in hand is to create p2p > >> connections between the routers via the L2 domain, using dedicated > >> VLANs. This way the L2 forwarding is forced to match the L3 > >> p2p topology. > >> > >> thanks, > >> Peter > >> > >> On 22.11.2010 17:36, Jeffrey (Zhaohui) Zhang wrote: > >>> Hi, > >>> > >>> I presented the draft > >> http://www.ietf.org/draft-nsheth-ospf-hybrid-bcast-and-p2mp-01 > >> .txt in Beijing (slides > >> http://www.ietf.org/proceedings/79/slides/ospf-9.ppt) and it > >> was deferred to the mailing list on whether the problem is > >> worth the working group effort (some who reviewed the draft > >> agreed that the proposed solution is reasonable for the problem). > >>> > >>> I'd like to request folks to review the draft/slides and > >> voice your opinion. We developed the solution for a real > >> network situation and would like to see that it gets > >> consensus and standardized so that more operators/vendors can > >> benefit from this. > >>> > >>> Thanks. > >>> Jeffrey > >>> _______________________________________________ > >>> OSPF mailing list > >>> [email protected] > >>> https://www.ietf.org/mailman/listinfo/ospf > >>> > >> > >> > > > > _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
