Single/Dual Homed and Multi-homed Designs

Hello Dakshinamurthy

Based on your description, we’re looking at something like this:

Now the first thing I’d say is in such a situation, you wouldn’t have the servers connected just to CE1 but you would find a way to have them connect to both CE1 and CE2 either via internal routing or using some first hop redundancy protocol like HSRP or VRRP.

However, if you want to maintain only a single physical connection from the servers to CE1, then you would at least have a connection between the two CE routers since they are on the same enterprise network. This way, both CE1 and CE2 will learn of the subnet of the servers, and can then be advertised to both ISP1 and ISP2.

Otherwise, if CE1 and CE2 are disconnected from each other, then we don’t have a multihomed network as you suggest but two separate enterprise networks each connected to a single ISP. The multihoming component of such an arrangement is nullified.

There are multiple ways to affect incoming traffic on a BGP enabled edge network with multiple ISPs. You can find out more about these possibilities at the following post:

I hope this has been helpful!

Laz