Build a not direct BGP connection question

[peichanhk]

                   I want to build up a bgp connection with my client. But there is no any ospf ..etc between of two bgp routers. And also, there is a layer 3 firewall between of them. ( BGP router --- L3 switch -- firewall -- client BGP router) If I don't want to use static route. Have any sugguest for this bgp connection?

[mahmoodmkl]

Hi

There should be any sort of connectivity for the TCP session to come up or else there will no BGP connection.

Thanks

[Richard Burts]

Most of the interior routing protocols (like OSPF and EIGRP) require that neighbors be on a common subnet. One of the advantages of BGP is that neighbors do not need to be in the same subnet (as is your case with the firewall in the middle). But BGP neighbors do need to be able to route packets to each other. You could use a dynamic routing protocol or you could use static routes for this. If your requirements are no dynamic routing and no static router then you have prevented BGP from working.

HTH

Rick

Sent from Cisco Technical Support iPad App

[peichanhk]

Since my client don't want to use interior routing protocols with me. At this moment, I use static route to handle it now. But I face a problem. When the customer shutdown their bgp interface, my static route will cause some problem. So I want to know have any other solution. I think a improvment, I may use the static route with checking to solve. Have any other suggest? Thanks all of you.

[milan.kulik]

Hi,

IMHO, you can use a static host route for the BGP neighbor to establish the BGP peering.

But then you are in another trouble:

The devices in the middle (the L3 switch and the FW) need to know how to route the packets sent from the client to your BGP router and vice versa.

But as the destination address in the packet is the remote target  (and those prefixes are exchanged via BGP), how could they know without any dynamic routing?

So you either need to configure some static routes on them or to involve some IGP and redistribute BGP into that IGP.

Or to start another BGP peerings between your router, L3 switch, FW and the client BGP router.

BR,

Milan