Hi, can you help me with this? Please see attached diagram.
Imagine I need to provide Internet Service Provider redundancy. I have two questions:
1) Is running iBGP and using local preference to determine the preferred route is through ISP1 (and then picking ISP2 in case of ISP1 failure) the best way to address redundancy for this?
2) If the answer for question above is yes, given the number of BGP prefixes on routers, am OK with 3750 switches, or should I be looking into 4507's for this (Given the additional memory capabilities)?
I have the impression that the 4507 is an overkiller, but let me know.
What I'm suggesting, if you don't already do so, is each 3745 shares it Internet routes with the other. So, if a route is not provided by one provider, that connected router will send to the other router (as it would if the AS path is shorter).
This would work whether you use HSRP or GLBP, the advantage of the latter is in case of tied AS paths. With HSRP, all traffic will exit off the gateway router unless there's a shorter path via the other. With GLBP, you start with a split but only transit via the peer if the path is shorter (or missing).
Besides the "normal" situation of a HSRP/GLBP taking all traffic if the other router fails completely, what you can do if the router is up but the WAN link fails on one, is track it. (You might even be able to track a peering failure of some type with the latest embedded monitor - unsure.) However, even without any tracking, if the router stays up but has no path out via its WAN link, it would redirect all its traffic to the other. (Tracking just tries to avoid this needless hop.)