On Jan 27, 2014, at 10:49 AM, Xuxiaohu wrote: > Hi Peter, > >> -----邮件原件----- >> 发件人: Peter Psenak [mailto:[email protected]] >> 发送时间: 2014年1月27日 16:41 >> 收件人: Xuxiaohu >> 抄送: [email protected]; [email protected] >> 主题: Re: [OSPF] fwd: New Version Notification for >> draft-xu-ospf-global-label-sid-adv-00.txt >> >> Xiaohu, >> >> >> 1. draft-psenak-ospf-segment-routing-extensions has already defined the >> mapping server functionality - please read the section 4.2 and 6.1 > > According to the description about mapping servers (see below) which is in > -01 version of the use case draft but is removed in -02 version of that > draft, it seems that the mapping server is deemed to advertise the mappings > on behalf of non-SR-capable routers.
As it is defined now, there is nothing that prevents the MS to be used for mapping SIDs/labels to indistinctly SR and non-SR routers. s. > In contrast, my draft proposes to allow the mapping server to allocate and > advertise mappings on behalf of SR-capable routers. Those two distinct design > goals cause different implications on the implementation and usage. > > "The mappings advertised by an SR mapping server result from local > policy information configured by the operator. IF PE3 had been SR > capable, the operator would have configured PE3 with node segment > 103. Instead, as PE3 is not SR capable, the operator configures that > policy at the SRMS and it is the latter which advertises the > mapping."---quoted from -01 version of the use case draft. > >> 2. TLVs that you defined in section 3 and 4 are very close to those defined >> in >> draft-psenak-ospf-segment-routing-extensions and have the exact same >> functionality as the ones defined in >> draft-psenak-ospf-segment-routing-extensions > > If I understand your draft correctly, the prefix SID sub-TLV defined in your > draft is intended to advertise index, rather than SID or global label. In > contrast, the Label Binding Sub-TLV and SID Binding Sub-TLV defined in my > draft are intended to advertise global labels and SIDs respectively. Besides, > the Label Binding Sub-TLV and SID Binding sub-TLV are just intended for label > or SID distribution without any correlation with the algorithm and MT-ID, > which is different from the prefix SID sub-TLV, IMHO. > >> 3. The only new sub-TLV you defined is Label Request Sub-TLV. >> >> First, given that we already have OSPF SR draft, you should have defined >> this as >> a sub-TLV of the OSPF Extended Prefix TLV that is defined in >> draft-psenak-ospf-segment-routing-extensions. > >> Second, you proposed to use Opaque LSA that is flooded either area or domain >> wide as a request mechanism between the router and mapping server. This >> means that all routers in an area/domain would have to store and maintain >> such >> 'request' LSAs, even though they would never use them locally. I seriously >> question if flooding of the LSA is the right mechanism to achieve what you >> want. > > Agree that it may not be attractive in the OSPF case. However, this choice > may be attractive in the IS-IS case since the label/SID request information > can be carried in the IP reachability advertisement. Anyway, as said in the > draft, the advertisement of label/SID request is just one option. > > Best regards, > Xiaohu > >> regards, >> Peter >> >> >> >> On 1/27/14 04:34 , Xuxiaohu wrote: >>> Hi all, >>> >>> Any comments are welcome. >>> >>> Best regards, >>> Xiaohu >>> >>>> -----邮件原件----- >>>> 发件人: [email protected] [mailto:[email protected]] >>>> 发送时间: 2014年1月21日 13:53 >>>> 收件人: Mach Chen; Mach Chen; Xuxiaohu; Xuxiaohu >>>> 主题: New Version Notification for >>>> draft-xu-ospf-global-label-sid-adv-00.txt >>>> >>>> >>>> A new version of I-D, draft-xu-ospf-global-label-sid-adv-00.txt >>>> has been successfully submitted by Xiaohu Xu and posted to the IETF >> repository. >>>> >>>> Name: draft-xu-ospf-global-label-sid-adv >>>> Revision: 00 >>>> Title: Advertising Global Labels or SIDs Using OSPF >>>> Document date: 2014-01-21 >>>> Group: Individual Submission >>>> Pages: 7 >>>> URL: >>>> http://www.ietf.org/internet-drafts/draft-xu-ospf-global-label-sid-ad >>>> v-00.txt >>>> Status: >>>> https://datatracker.ietf.org/doc/draft-xu-ospf-global-label-sid-adv/ >>>> Htmlized: >>>> http://tools.ietf.org/html/draft-xu-ospf-global-label-sid-adv-00 >>>> >>>> >>>> Abstract: >>>> Segment Routing (SR) is a new MPLS paradigm in which each >> SR-capable >>>> router is required to advertise global MPLS labels or Segment IDs >>>> (SID) for its attached prefixes by using link-state IGPs, e.g., OSPF. >>>> One major challenge associated with such global MPLS label or SID >>>> advertisement mechanism is how to avoid a given global MPLS label or >>>> SID from being allocated by different routers to different prefixes. >>>> Although such global label or SID allocation collision problem can be >>>> addressed through manual allocation , it is error-prone and >>>> nonautomatic therefore may not be suitable in large-scale SR network >>>> environments. This document proposes an alternative approach for >>>> allocating and advertising global MPLS labels or SIDs via OSPF so as >>>> to eliminate the potential risk of label allocation collision. >>>> >>>> >>>> >>>> >>>> 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 >>> >>> _______________________________________________ >>> OSPF mailing list >>> [email protected] >>> https://www.ietf.org/mailman/listinfo/ospf >>> > > _______________________________________________ > OSPF mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/ospf _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
