Ok I have setup internal BGP on the 2 routers behind the final border router. For understanding lets say rtr 1, rtr2, & rtr 3. Rtr 1 is doing external BGP with 2 ISP’s…Rtr1 is using a static route to Rtr2 for all Public IP’s we own, rtr2 & rtr3 are doing BGP for load balancing purposes (I am connecting rtr 2 and rtr 3 via 2 seperate interfaces…using neteq’s that only support 20megs atm is the reason for this, so i can neteq 40megs). rtr 3 is doing BGP on the external and OSPF on the inside. Ok now my question is, why did i have to put all of our subnets in the advertisements to make the routing filters work properly. If I put the entire block we own into the advertisements from rtr 3 to rtr 2, the more specific routes and their respective filters are not being used. Using 4.17 on rtr 3 and 5.1 on rtr2, I understand upgrading might be a solution, however these are in production. Has anyone ran into an issue like this before?
You may have more luck getting an answer if you post some configuration details, including a network diagram, interface statuses, IP addressing and routing tables (unless there’s lots and lots of routes), as well as your BGP configuration.
There are more routes than I would like to post, I was really hoping i could avoid all that since it is not a major problem. I will post a network diagram later today. Fewi I know you atleast know wut I am talking about, does it make any sense to you why I would have to advertise each subnet individually into BGP to make routing filters work. Seems to me I should be able to put 10.0.0.0/8 into my BGP advertisement, and then use routing filters to send 10.0.0.0/16 and 10.1.0.0/16 down 2 different interfaces.
I am curious to see your network diagram. I am planning (half way through implementing) a similar network. I actually came here to look for a best practices for setting up routes between my bgp edge routers and distribution. What IP’s to use? For example
Router1 Peers with L3, they give me a /30 for the wan and a /24 for whatever
Router2 Peers with Verizon, they give me a /30 and 4 separate /24
I am waiting on a direct allocation from arin.
Router 3/4 distribution, They have those 4x /24 and part of the 5th one I mentioned earlier routed out to equipment or customers.
I am using the rest of the fifth /24 to link up the router 1,2,3 (broken into a /30 for each link)
Is that bad? Is there a better way to connect the routers to each other?
No, you cannot do that. In bgp networks you add specific prefixes that you want to advertise. If you want to advertise 10.0.0.0/16 and 10.1.0.0/16 then you have to add to the networks both of them. Then in routing filters you can accept both prefixes with one rule matching prefix 10.0.0.0/8.