Hi, Dear Adrian, I am confused by the explanation you provided below.
My question originated from the definition of an active PCE provided in section 17(copied in below). An Active PCE is one that issues provisioning "recommendations" to the network. These recommendations may be new routes for existing LSPs, or routes for new LSPs. In Section 19, it only talks about LSP delegation(which means "new routes for existing LSPs"). Thus, the second part, i.e. "routes for new LSPs" is ruled out. So, my question was about why that second part is left out, (which i call another sub-type of an active PCE). From your explanation below, it seems to me that an active PCE should not even provide routes for new LSPs? I understand that for a passive PCE, it is ineed a recommendation since the PCC can decide it can discard the route suggestion from a PCE and use a complete different route. But I do not see the difference in the active PCE case(recommendations=provisioning). If the control of a LSP is handed over to the PCE, then when it returns the "recommendations" to the PCC, the PCC has to start the provisioning straightaway. So, no matter whatever we call it, it has the same effect, i.e. a new LSP will be set up, right? Regards, Xian ________________________________________ 发件人: Adrian Farrel [[email protected]] 发送时间: 2013年2月22日 5:50 到: Zhangxian (Xian) Cc: [email protected] 主题: RE: [Pce] Ramblings of two old dogs Hi Xian, I was just going through everyone's comments to update the draft and I had a question about one of the points you raised... > Q19: > Is there a reason why the other sub-type of an active PCE is left out? IMHO, an > active PCE with the ability to issue new route recommendations would be also, > maybe even more, like an NMS, as compared to the case mentioned. For an > active PCE with LSP delegation, at least the LSP is initiated by the head-end nodes > and it has the root control when needed. :-) I wondered what you meant by "sub-type of an active PCE". Possibly you mean stateful vs stateless. Or maybe you are suggesting that there are two types "recommend paths" and "provision paths". In the first case, I don't think there is any distinction to be made. As the current text notes, an Active PCE is likely to hold state for at least the LSPs for which it can issue route recommendations. In the second case you would be suggesting an option I personally don't consider is allowable. That is, a PCE cannot, IMHO, provision paths. It can only issue recommendations for rerouting of LSPs that have been delegated to it. Thus you have drawn out an important distinction between an NMS and an Active PCE. That is, the NMS can provision new LSP and has control over existing LSPs. The Active PCE cannot provision new LSPs and can only suggest changes to existing LSPs. I have added a little text about this to Section 19. Cheers, Adrian _______________________________________________ Pce mailing list [email protected] https://www.ietf.org/mailman/listinfo/pce
