Hi folks, A bunch of collaborators and I worked on the problem of IGP migration/reconfiguration before. Basically, we augmented Vijay’s methodology to guarantee its correctness. Indeed, when you start flipping Administrative Distance (AD) between IGP1 and IGP2, bad stuff (i.e., forwarding loops, BGP oscillations) can happen if you’re not careful. Also, what Vijay describes is a migration between two Link State (LS) protocols (in this case, OSPF to ISIS). Migrating from EIGRP to a LS has to be treated differently since EIGRP is a Distance Vector (DV) protocol: when you flip the AD on router X, routing decisions at router Y can be impacted (this was not the case in the AOL migration). Fortunately, we managed to get that case covered to.
If you’re interested in knowing more, we covered the LS-to-LS migration case in “Seamless Network-Wide IGP Migrations” (see http://vanbever.eu/pdfs/vanbever_igpmig_sigcomm_2011.pdf). Our work about DV-to/from-LS is not published yet, but I’d be happy to share it privately (just ping me). Also, something to keep in mind when you start messing with an IGP: usually, there is BGP running on top of it… And changing the IGP can make BGP decisions go crazy (the decision process rely on IGP cost). We described this in another work “When the Cure is Worse than the Disease: the Impact of Graceful IGP Operations on BGP” (http://vanbever.eu/pdfs/vanbever_igp_bgp_infocom_2013.pdf). Nick, I’d be happy to chat OOB if you want to know more or go further with this migration. Cheers, — Laurent On Jan 24, 2014, at 8:04 AM, Jimmy Hess <mysi...@gmail.com> wrote: > On Fri, Jan 10, 2014 at 9:57 AM, Christopher Morrow <morrowc.li...@gmail.com >> wrote: > >> On Fri, Jan 10, 2014 at 10:54 AM, Nick Hilliard <n...@foobar.org> wrote: >>> On 08/01/2014 18:14, Christopher Morrow wrote: >>>> question... there's people that have done this before even :) >>> https://www.nanog.org/meetings/nanog29/presentations/gill.pdf >> >> oh yea! that guy! I hear he's done this sort of thing a few times >> now... probably has practice and tools and stuff :) >> > > Hey... Tools.... why not... Control+Click... select all the routers.... > Right click "Upgrade IGP to ISIS" > > Go grab a drink... Come back... "Done" click OK. No more Eigrp. > > I suppose PuTTy / SecureCRT haven't added the feature yet... > perhaps in a few releases? :) > > > -- > -JH
