Hi Richard
> > The flow label helps the router select the instance for a packet. > > "Helps"? Doesn't the flow label tell the router exactly which instance to use? At the moment you're correct, it's one to one. I've heard voices (was that Kris and Phil?) asking for a more complex stateful mapping at the RPL network ingress, and a new field in the new RPL option for the instance. My vote is to leave the instance ID in the flow label where it is today, since it is end to end application data. While I agree that the loop avoidance data fits very well in a hop by hop option long as the option stays contained in the RPL network. Which is what Jonathan's draft does for all I understand so I'm fully happy there. > > The trouble I have with this is that "select a router" > sounds a lot like routing. We already have a mechanism for selecting which > router to send a packet to: DIOs. > If a device wants to select between next hops based on routing metrics then > it should be a router. > > Why is this such a burden? Listening to DIOs and making routing decisions > based on them does not require sending DIOs or forwarding packets for > others. In the host world, there is such a thing as a default router list. The host builds that list listening to RAs, and applies its best practice to select the router it will use for a given packet out. A number of considerations will influence that decision, like the age information, Mobile IP information, multihoming information, etc... RFC 4191 is an obvious such consideration that provides guidance to proactively setup a table that redirects would have setup reactively anyway. You'll note that RFC 4191 is very voluntarily NOT a routing protocol thing, and really a router to host to interface. The key here is that the preference IS NOT a distance. Other hints come from the mechanics used (RA most usually is router to host though it's been extended to R2R sometimes like in MIPv6). In a same fashion as routing information can be transformed into a RFC 4191 RIO, instance information should be made available to the host. Pascal > -----Original Message----- > From: Richard Kelsey [mailto:[email protected]] > Sent: Friday, May 07, 2010 4:52 PM > To: Pascal Thubert (pthubert) > Cc: [email protected]; [email protected]; > [email protected]; [email protected] > Subject: Re: [Roll] [6lowpan] how does a node get an IP address > > References: > <[email protected]><4bd58ed9.8070...@gridmerg > e.com><[email protected] > .local><[email protected]><0a9b01cae5a3$79d6a320$6d83 > e9...@com><6a2a459175dabe4bb11de2026aa50a5d01bca...@xmb- > AMS-107.cisco.com><87d3xl0zmn....@kelsey- > ws.hq.ember.com><[email protected]><87bpd42 > 9wp....@kelsey- > ws.hq.ember.com><[email protected] > .fi> <6a2a459175dabe4bb11de2026aa50a5d01c46...@xmb-ams- > 107.cisco.com> <8a977bdc5a7b0e429b0f521e8d6f91ee01f6d...@xmb- > AMS-103.cisco.com> <[email protected]> > <6a2a459175dabe4bb11de2026aa50a5d01cd9...@xmb-ams- > 107.cisco.com> <[email protected]> > <6a2a459175dabe4bb11de2026aa50a5d01cd9...@xmb-ams- > 107.cisco.com> <[email protected]> > <[email protected]> > <6a2a459175dabe4bb11de2026aa50a5d01d60...@xmb-ams- > 107.cisco.com> <[email protected]> > <6a2a459175dabe4bb11de2026aa50a5d01d60...@xmb-ams- > 107.cisco.com> > X-OriginalArrivalTime: 07 May 2010 15:01:59.0538 (UTC) > FILETIME=[3E3CA520:01CAEDF6] > Return-Path: [email protected] > > > Date: Fri, 7 May 2010 16:33:41 +0200 > > From: "Pascal Thubert (pthubert)" <[email protected]> > > > > The flow label helps the router select the instance for a packet. > > "Helps"? Doesn't the flow label tell the router exactly which instance to use? > > > It does not help a host that needs to select a router that serves that > > instance. > > The trouble I have with this is that "select a router" > sounds a lot like routing. We already have a mechanism for selecting which > router to send a packet to: DIOs. > If a device wants to select between next hops based on routing metrics then > it should be a router. > > Why is this such a burden? Listening to DIOs and making routing decisions > based on them does not require sending DIOs or forwarding packets for > others. > > -Richard Kelsey _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
