Thomas, > -----Original Message----- > From: ipv6-boun...@ietf.org [mailto:ipv6-boun...@ietf.org] On Behalf Of > Thomas Narten > Sent: Tuesday, November 24, 2009 11:37 AM > To: Templin, Fred L > Cc: ipv6@ietf.org > Subject: Re: New draft on "Stub Router Advertisements in IPv6 > NeighborDiscovery" > > Fred, > > Can you summarize what problem this draft is aimed at solving? What > is the motivation for this draft? (I've read it, but I don't > understand what the benefit of this approach is or what problem it > solves.)
When a stub router connects a stub network to a link, it needs to somehow be provisioned with one or more default routes pointing to other routers on the link that can forward packets on toward a provider network. The normal IPv6 ND mechanism for this is RS/RA, but if the stub router were to send an RS the routers that receive it would immediately set 'isrouter' to FALSE and we don't want that. At the same time, the stub router may need to publish its prefixes with other routers, and it can do so by including RFC4191 Route Information Options in the RAs that it sends. A valid question is why not just run a routing protocol between all the routers on the link? That may be the preferred method in some cases, but when there are many, many routers on the link the control overhead would be excessive when only a few default routes are needed. Also, discovery of other routers on the link in order to bootstrap neighbor relationships may be difficult to automate on links such as NBMA. But the simplest explanation is that RFC4861 currently says that routers send RAs irrespective of whether/not they are authoritative for the link. So, this spec updates RFC4861 by specifying appropriate limits on the information stub routers may include in their RAs. Fred fred.l.temp...@boeing.com > Thomas > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > ipv6@ietf.org > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
