There was a discussion at the Cisco Learning Network (CLN) about OSPF as PE to CE protocol. I wanted to provide some pointers on using OSPF as PE to CE protocol. RFC 4577 describes how to use OSPF as PE
Scaling PEs in MPLS VPN – Route Target Constraint (RTC)
Introduction In any decent sized service provider or even an enterprise network running MPLS VPN, it will most likely be using Route Reflectors (RR). As described in a previous post iBGP fully meshed does not really scale. By default all
iBGP – Fully meshed vs Route Reflection
Intro This post looks at the pros and cons with BGP Route Reflection compared to running an iBGP full mesh. Full mesh Because iBGP routes are not propagated to iBGP sessions there must be a full mesh inside the BGP
BGP wedgies – Why isn’t my routing policy having effect?
Intro Brian McGahan from INE introduced me to something interesting the other day. BGP wedgie, what is that? I had never heard of it before although I’ve heard of such things occuring. A BGP wedgie is when a BGP configuration
Default routes in BGP
I have seen in forums and in other places that some find that the default route in BGP is a bit confusing. There are multiple ways of orginating a default route in BGP. To start this is the topology used:
Some important details of BGP
We start out with a basic topopology of 3 routers. R2 and R3 will peer to each others loopback. I have setup OSPF for full reachability in the network. First we test connectivity. R2#ping 3.3.3.3 so lo0 Type escape sequence
Conditional BGP, showing status
This is some notes for the post that I did on conditional BGP advertisement. I found an easier way of seeing the status for the advertise-map. It is available by looking at the neighbor status, look at the following output.
Conditional BGP advertisement with advertise-map
This post will describe how to do conditional advertising with BGP. In a real life scenario this can be used to only announce routes to your backup provider when your primary link is down. In a lab scenario this can
BGP troubleshooting – route not installed
Sometimes prefixes in BGP do not get installed into the routing table, if the route is also in an IGP that might be a reason but then a RIB-failure would be indicated. This scenario shows another possible source of problems.
BGP added to flash cards
I have added content for BGP to the flash cards. There is now a total of 112 questions so far. More content in other areas will be added as I go through them in my studies. The file as always