I'm not sure what your plan is with that /24. If you advertise that /20 out both providers, the entire Internet can reach that /20 from either provider. If either provider fails, your entire address space is available on the other. No need to do anything except contact your failed upstream to get the connection repaired. If you want to weight traffic based on (relative) geography, advertise the /20 out both providers in addition to one /21 out provider A and one /21 out provider B. Traffic will prefer the /19 until that provider fails.
----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com ----- Original Message ----- From: "Ty Featherling" <[email protected]> To: "Mikrotik discussions" <[email protected]> Sent: Wednesday, March 19, 2014 7:51:18 PM Subject: Re: [Mikrotik] BGP guidance We have a /20 assignment that I will be using on both sides. I intend to have a /24 on each side that will fail over. -Ty On Mar 19, 2014 5:19 PM, "Mike Hammett" <[email protected]> wrote: > Just as an example, if you have a /23 from both providers, announce that > /23 on both connections. Then, advertise the two /24s comprising the /23 on > the ISP you want to use it from. I believe BGP will take a longer prefix > before a prepend. The smallest you can advertise, though, is a /24, so if > your blocks are smaller, that won't work. > > > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > ----- Original Message ----- > > From: "Ty Featherling" <[email protected]> > To: "Mikrotik discussions" <[email protected]> > Sent: Wednesday, March 19, 2014 2:11:43 PM > Subject: [Mikrotik] BGP guidance > > I am ready to begin turning up BGP on both of my edge routers and start > advertising my new IPv4 assignment. I am want to make sure I understand > things clearly first. > > These were setup as two separate networks, each with their own upstream. We > built out between them and got a backhaul between the two so we could > manage the far network from the one we have our office already on. I turned > up OSPF recently on all routers and the routes for both networks are shared > between the two edge routers. > > Now we have our own IP space and would like to start advertising/using it. > That seems easy enough. Turn BGP on between the edge routers and our > upstream providers and advertise some addresses on one and some on the > other. The real fun begins when we want to have fail-over between the two. > Initially this will only be for some VIP clients like ISDs and Hospitals. > In the event of an outage upstream of either network I would like to make > sure these clients stay up across the backhaul between networks. > > I believe the way to accomplish this is just to announce the space used by > those clients to both upstream ASes and just prepend the ones that normally > live on the other network. That way should the upstream go down, the > "farther" path will become active. Beyond that I just need to have iBGP > running between my two edge routers so those routes are known. Does this > sound right? > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://mail.butchevans.com/pipermail/mikrotik/attachments/20140319/5b3303be/attachment.html > > > > _______________________________________________ > Mikrotik mailing list > [email protected] > http://mail.butchevans.com/mailman/listinfo/mikrotik > > Visit http://blog.butchevans.com/ for tutorials related to Mikrotik > RouterOS > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://mail.butchevans.com/pipermail/mikrotik/attachments/20140319/da153495/attachment.html > > > > _______________________________________________ > Mikrotik mailing list > [email protected] > http://mail.butchevans.com/mailman/listinfo/mikrotik > > Visit http://blog.butchevans.com/ for tutorials related to Mikrotik > RouterOS > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.butchevans.com/pipermail/mikrotik/attachments/20140319/9631979e/attachment.html> _______________________________________________ Mikrotik mailing list [email protected] http://mail.butchevans.com/mailman/listinfo/mikrotik Visit http://blog.butchevans.com/ for tutorials related to Mikrotik RouterOS -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.butchevans.com/pipermail/mikrotik/attachments/20140319/338fe859/attachment.html> _______________________________________________ Mikrotik mailing list [email protected] http://mail.butchevans.com/mailman/listinfo/mikrotik Visit http://blog.butchevans.com/ for tutorials related to Mikrotik RouterOS
