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Best use of BGP across a WAN

We have a 20mb internet at location A and location B. They are connected via 20Mb MPLS.

I was considering BGP but what would happen if the WAN were down and Internet at location A went down.

Location A has /26 and location B has a /24 we do have an ASN.

Would Radware or F5 handle this better?

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1 Solution

There is not much that you can do with the /26, at least from a advertisement upstream perspective.
Most ISP's will not allow anything longer than a /24. BGP is a great protocol to use in this
application; however, you would utilize BGP to advertise outbound, and any type of traffic engineering methodologies, etc. You could advertise the /24 out via both providers assuming they will allow BGP peering; this would involve LOA's and possible registering via RADB. You would then utilize iBGP between location A and location B and set a metrics for the default routes and possible adjusting the local_pref on received routes from your peers.

If the BGP configuration was properly setup, failover would just work and in most cases with
BFD and a internal routing protocol (OSPF), convergence can be sub-millisecond capable.

To answer your question, if the MPLS connection when down and the connection to the ISP at location A went down, location A would be in the dark with only local communications available. The likely hood that both connections going down at the same time is very unlikely, but possible. If this is important, then you would get another WAN connection from a different provider.


timz955Author Commented:
So lets say that internet traffic goes to location A and get to the servers a location B via  the MPLS.

This depends on the MPLS being up from A to B. Would s2s VPN useful in this scenario?

Also, is there any use for the /26?

>This depends on the MPLS being up from A to B. Would s2s VPN useful in this scenario?
No, a S2S VPN would not be useful, you have a private WAN link between locations.
Of course a S2S VPN between locations exiting the ISP would be useful for internal use if the WAN connection went down, but not for customer use. When you start depending on connectivity between data centers for customers, you will want to consider redundant physical links, not logical links.

The /26 is useless for internal use and customers if multihoming is used; there are ways to make it work, but it would be far from being 'Best Practice'.


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