Hello Dino, there was another question I forgot regarding the notifications: so when the map-notification is not used as an ACK for map-register but is actually informing the ETRs about events then how is the delivery guaranteed? The underlying IP/UDP transport may drop.
For map-register we periodically send again, so packet loss of map-registers is not a big problem. What is your idea for map-notifies? Some of the notifications may be singular events. Other of course could be periodic (e.g. merge notification triggered by the map-registers?). Would I need an ACK for the map-notification (and some fast-timer re-send, e.g. every 1sec until ACKed) ? That would take state/timer, although only until's it's ACKnowledged. Thanks & Regards, Marc On Mon, 17 Feb 2014 10:13:16 -0800, Dino Farinacci wrote: >> Hello LISP experts, >> >> have two questions, mainly to understand the context a bit better. > > No prob Marc. Thanks for the email. I'll attempt to answer them but > others can chime in as well. > >> Q1: map-notify message. >> >> maybe it's the name but I always expected this message is for the Map >> Server to inform ETRs. Kind of a "push" method. But reading RFCs 6830 > > That is exactly what it is. It is used as a event notification from > the Map-Server to the ETRs that register for a particular EID-prefix. > So when a locator-set changes, the old locators can be notified. The > main reason to call it a "Map-Notify" was for this purpose. And you > can now understand why by looking at the data-center use-case > documents that have been published by Yves and Victor. > >> and 6833 again it seems that the Map-Notify is simply an ACK for a >> received and processed Map-Register message. Take the Map-Register >> message, set the type to Map-Notify and send back. > > So when a registerer requests Map-Notifies, it will get them for > various reasons. The first is the case I said above and the other > case is to acknowledge a Map-Register. > >> Now, the use as ACK is not a contradiction to the broader use as a push >> message. So my question to the LISP experts and inventors is: is >> Map-Notify restricted to be just an ACK? (having an extra type for it >> seems generous) > > It is not restricted to just an ack. There is also another use case. > Here it is: > > (1) You have two xTRs, each sitting behind different NAT devices. > (2) The xTRs get private addresses assigned to their interfaces. So > they are using them as "local RLOCs". But no one will be able to > encapsulate to them so they need to find out their global RLOC > addresses. > (3) Each of the two xTRs are at the same LISP site and can receive > encapsulated packets for the same EID-prefix. > (4) When they each discover their global RLOCs (by mechanisms > descrbied in draft-ermagen-lisp-nat-traversal), they each register > their own global RLOC. They register with the "merge-request" bit set > so the Map-Server will add both xTR global RLOCs to the locator-set. > (5) So now, if an xTR gets a Map-Request, it will want to send a > Map-Reply with the merged-locator set. Well how will it do that when > it only knows its own? > (6) A Map-Notify is used here by the Map-Server to tell each xTR > about the other's global RLOC. > _______________________________________________ lisp mailing list [email protected] https://www.ietf.org/mailman/listinfo/lisp
