Hello Everyone,
I would like to begin by apologizing and also begin by saying thank you for your assistance. Below you will find the problem I'm facing and difficulty I'm having when creating a fully functional and operation peering relationship between eBGP neighbors and iBGP neighbors.
In this scenario there are 2 different BGP relationships, an eBGP relationship and an iBGP relationship. I will begin by describing the eBGP relationship I have.
Below you will find the topology of our eBGP relationship. We have what we will call our traditional Router A and Router B. There routers are GSR routers, they are the Gateway out of our Autonomous System, they have the following characteristics.
1. They peer on the physical interfaces
2. In the BGP neighborship configuration there is a prefix-list that blocks all routes out of our AS that are not part of our ip address scheme, meaning we have summarized 6 x /15 routes, if there is a route that does not belong to the /15 route it is not passed along.
3. Router A and Router B receive the Full Routing Table from the our internet partners.
4. Note: The cloud represents the internet.
Now, an introduction into our Autonomous System, the GSR routers are connected to 2 Cisco 7000 series routers in a full-mesh as illustrated below.
1. Router A and Router B receive the FRT from our Internet Peer.
2. They DO NOT pass the FRT to router C or D, but rather only the default route via BGP.
3. ISIS is the routing protocol used to reach the loopbacks of this iBGP peering relationship.
4. Router C and D accumulates all the routes within our AS and advertise these routes via iBGP to Router A and Router B. So, Router A and Router B have the Full Routing Table as well as the routes of our internal AS.
This is were the confusion happens.
Above I wrote that there is a prefix-list on Router A and Router B that prevents all the routes that don't belong to the 6 x /15 routes out to the internet remember?
Anyways, on Router A and on Router B there are 6 static routes to the same 6 x /15 subnet pointing into our AS via static route to the physical interface on Router C the same thing from Router B to Router D's physical interface?? Why??
And when taken away does not announce our network anymore to our internet peer.
When this happens (Removing the static routes that point into our AS) Router A doesn't receive any download because it's not advertising the network anymore to our internet peer but the upload works perfectly fine. Our internet peer doesn't receive networks from Router A and passes all the traffic to Router B risking saturation.
After analyzing the situation further, it seems that the following happens at an iBGP level:
My problem is this:
Why aren't the routes being considered?
Why are the static routes pointing into our AS???,
Why are the static routes pointing into our AS being advertised to our internet peer and not the routes learned via iBGP from Router A and Router B??
They should be automatically learned and known!!
Why when I take away those static routes, our GSR doesn't advertise our Network anymore??
What should happen is the following.
The GSR should receive and consider all routes arriving from Router C and Router D and advertise these routes to our Internet peer via a summarized prefix.
The links should properly load-balance from a download point of view and be able to self-sustain itself at a routing stand point..
I hope I was clear.. please let me know if you need anymore information.. Please and thank you
