Hi Deguang, sorry for the late reply... El 12/10/2006, a las 22:59, Deguang Le escribió:
Thank you very much for your detailed explanations. And I find that the similar statements are presented in Page 113. However, I still can not understand well why we need the "synchronization". :-)At first, I can not understand what the "synchronization" means exactly.To my understanding of your statements. I guess that the "synchronization" is a mechanism through which the communicating SHIM6hosts can know what the current locator set is, because the communicating SHIM6 host don't know what the current locator set is. Right? :-)
i am not sure what do you mean here...two shim hosts would end up out of synch in the case where a host A has a locator set LsA but the host B thinks that A has a locator set LsA* which differs from LsA. In this case since A sends incremental updates, they will never get in sync again. In the atomic approach, eachg update contains all the locator set, so in the case this happens, it would be corrected upon the recepntion of the newest UPDATe message, so the out of sync problem is more easily dealt with
hope this helps. regards, marcelo
If my understanding is correct, I however don't understand why both SHIM6 hosts don't have the same idea about what the current locator set is. I think the current locator set is in the SHIM6 context, in other words, each SHIM6 context has (or keep) a current locator set. If the SHIM6 context have been established, the SHIM6 host can obviously know what the current locator set is through the SHIM6 context, which is identified by the context tag, because both SHIM6 host can know the context tag. Right? :-)If my above issue is reasonable, do you think it is possible to definetwo new separate options (e.g. Locator Addtion option and LocatorDeletion option) for adding a new locator to the locator set on a SHIM6context and for deleting a failured locator from the locator set on a SHIM6 context.see above...absolutely, this is possible and a shim6 host can use it in the way you proposeIf the above two examples belong to the "locator change" situation, then I would like to know if a SHIM6 host must (or can or need to) send the Locator Request message with Locator List option to its peers when the SHIM6 host is assigned a new usable locator at some interface of the SHIM6 host or when the SHIM6 host finds one of its locators is unusable or failure.but this would be up to the host to decide based in its local policy rather than a protocol issue imhoYou are right, and I know what you mean. But, I'd only like to know,from the functionality point of view, if the Update Request message withLocator List option "CAN" be used for this purpose when the above two situations occur. :-) From the your following explanations, I think you agree the Update Request message with Locator List option "CAN" do this.right, but this is a multihoming solution.... whether this can or not be used for mobility is another issue and i think it is explicitly out of the scope of the wg (see the charter)I mean if a host has a new locator it can either add it to all of its established contexts, or to some of them or none of them depending of local considerations. Moreover, a host does not need to add all its locator to all its shim contexts. for instance a host could have a set of locators tha it uses for certain communications (e.g. communications within its own site) and some other set of locators that it uses for other communications (e.g. intersite communications) All these cases are perfectly ok and the spec supports any behaviour that the host decides to choose A similar consideration applies to the case where the host looses on locator. Depending on the situation it can either rmove from the locator set using an Update message or it can mark it as broken using the preference option or it can even do nothing and the peer will determine that the locator pairs contianing this locator are unreachable and will not use them. All these approaches are possibel and they are supported in the spec. So, i am not sure we need to add additional constraints on how ths needs to be used, what do you think?Thank you again, I think your answer confirms my understanding.This draft specifies the messages, which are used for multihoming, but it does not clearly present (or explain) if these specifications couldbe appled for mobilty usage.Yes, you are right. I know SHIM6 is currently for multihoming solution, nor for mobility, and multihoming related issues are mainly discussed in SHIM wg. Since mobility and multihoming have some commen features, and mobility will be ubiquitous on the future Internet, we also need to investiages the possible applications in mobile environments (like the drafts: draft-bagnulo-shim6-mip-00 and draft-ietf-shim6-applicability-01 ), even the potential of mobility support. :-)Cheers, DeguangHowever, the shim6 protocol can work with mobility protocolos like MIP and their interaction is detailed in the applibility statement drafti think you could, but as i mention this is explicitly out of the scope of the wgSo, the reasion why I ask these questions and make these comments isthat I am not sure if SHIM6 can be used in the mobile environments where a host may change its attachment/location to Internet, namely change thelocator (including locator additon and locator deletion).In fact, the above two examples I described are exactly the situationsthat appear in the mobile environments. To my understanding, the specified locator update messages also can be used for mobility scenario. Now your answer confirms my understanding. Right?Regards, marceloRegards, marceloCheers, Deguang Geoff Huston schrieb:Hi,This note starts the WG Last Call for comments on the three "base" Shim6 documents: draft-ietf-shim6-proto-05.txt "Level 3 multihoming shim protocol" draft-ietf-shim6-hba-01 "Hash Based Addresses (HBA)" draft-ietf-shim6-failure-detection-06 "Failure Detection and Locator Pair Exploration Protocol for IPv6Multihoming" They can be found at:http://www.ietf.org/internet-drafts/draft-ietf-shim6-proto-05.txthttp://www.ietf.org/internet-drafts/draft-ietf-shim6-hba-01.txthttp://www.ietf.org/internet-drafts/draft-ietf-shim6-failure- detection-06.txt Please review the documents carefully, and send your feedback to the SHIM6 list. Please also indicate whether or not you believe that these documents are ready to go to the IESG for publication as a set of Proposed Standards. This Working Group Last Call will end in two weeks, on the 12th October 2006 at 0800, UTC+10Thanks, Geoff & Kurtis