BGP Route Reflectors Example
Continuing on with route reflectors, here is an example. The specifics of the topology don’t matter too much. R0, R1, R3, and R6 are all in AS1 and happen to be sitting on the same LAN segment. R1...
View ArticleBGP Peer Groups
A simple one to get the posts flowing… BGP peer groups simplify the configuration of BGP neighbors by moving the template into a configuration. For example, look at R3: router bgp 1 no synchronization...
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Redistribution involving IS-IS
I’ve read and heard that there are some idiosyncrasities about connected routes and IS-IS when redistributing. Most recently while reading “Optimal Routing Design” and also when talking with a friend...
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EIGRP Stub Routers
Routing protocols, especially EIGRP, are very good at finding ways around network faults. I remember one time where we had a LAN failure, but a router on each side of the break happened to be...
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Multicast – PIM implementation and testing with MRM
Implementation of multicast, at least for the purposes of the CCNP BCMSN exam, is pretty simple. Cisco has the Multicast Quick-Start Configuration Guide which goes over many different ways of doing it....
View ArticleOSPF special areas: stubby, not so stubby, and totally stubby
I’ve been doing some prep for BSCI lately and am back into OSPF. One thing I ran into was keeping the various types of areas straight, and remembering all the restrictions that come with them. It...
View ArticleOSPF Special Areas, with examples
Earlier I gave a description of OSPF special areas (stubby, not so stubby, totally stubby). Here’s some examples to back it up. I use dynagen to simulate my environment, it’s so good I ended up selling...
View ArticleNot So Stubby Areas
Earlier I looked at stub areas. One problem we found was that you can’t have an ASBR in a stub area — no “redistribute static” on any external links. What a pity! Not so stubby areas get around this by...
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EIGRP Stub Routers again
When an EIGRP enabled router loses a neighbour, all routes through that neighbour need to be re-evaluated. Any feasible successors are immediately promoted to successors, and any other routes go...
View ArticleDefault routes
The other day I ran into some problems with a default route, which prompted a discussion with co-workers, which led me to look up the behavior of redistributing a static default route into a dynamic...
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