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Is it better to purchase a larger Public IP block or consolidate current IP's in order for new modem to work with IBGP failover?

rivkamak used Ask the Experts™

Our company internet provider set us up with a new modem which would deliver faster speeds and has the IBGP failover ability. In order to use the IBGP failover we would need to designate 1 (or 2?) IP's from our small block of IP's, or get rid of the current ones and use a larger block of IP's.

Does it make sense to just consolidate our current IP's instead of purchasing a larger block of IP's? We currently have 5 public (outside of the broadcast)

Is it best practice/ industry standard to purchase larger amount of public IP's?

Thank you.
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In reality, you don't really need a huge block of IP address if you provision your network properly.

2 for IBGP failover should be fine along with afew extra for Web or other devices that you would like to access outside of your local LAN.

Other than that, really all you need to do is setup your applications to utilize port address translation.

Here is a good site that outlines this :

Ibgp failover allows failover of multiple wan links using the same address pool.

so ibgp has no direct relation with the size of the wan pool or pools in use


Wouldnt I need to dedicate one of the IP's in my WAN pool for the failover to work?
those do not need to be WAN addresses, but that would depend on your setup and agreement with your peers.


the current practice would be to use either few addresses or ipv6. it is also nowadays become frequent to use different IPs on different links and provide applicative failover rather than rely on the network infrastructure. whenever possible of course.

also note that a single ip can host MANY services. i have no idea what you host, but it is very unlikely you actually NEED many ips. it may be more convenient, though.


Thank you.