BGP Advertisement

[NetworkGuy!]

All

could you please let me know how to advertise these subnets on BGP? (attached diagram)

My understanding is have a static route from the firewall for 172.16.16.0/24 poitning back to 10.10.10.2 and advertise that static route via route-map through ebgp?

[chrihussey]

Simply put, for a network to be advertised in BGP, it needs to exist in some form. The static route to 10.10.10.2 meets this requirement. You could redistribute the static via BGP, or even simpler you could just add it as a network statement in BGP.

Either one should work.

Hope this helps. 

[NetworkGuy!]

will it work if i add it as a network statement under BGP as the network itself does NOT hang off the firewall?

is this the same case if it was ospf as well?

[chrihussey]

For BGP to advertise a network it needs to see it in the IGP (static, EIGRP, OSPF, etc.). So as stated earlier the network statement or redistribution of static would work.

For OSPF to advertise a network with a network statement, it needs to be an attached network. If it is based on a static route it has to be redistributed as the network statement would not apply.

Hope that clarifies things.

[NetworkGuy!]

now will i need a route-map to limit what advertisements i receive? - is that a must?

and do i need a route-map to limit what i send (or is the network statement enough to cover this)? 

[chrihussey · Accepted solution]

now will i need a route-map to limit what advertisements i receive? - is that a must?

ANS. It is not a must, but depending on your environment it is not a bad idea. If you know what you are expecting to receive, it can't hurt to avoid getting advertisements you don't want. It doesn't necessarily have to be done with route maps either. You can filter with ACLs, as-path, prefix-lists, etc.

do i need a route-map to limit what i send (or is the network statement enough to cover this)?

ANS. The network statement should suffice, but there is nothing wrong with adding another level of control to avoid advertising anything you don't want. Again it doesn't only have to be done with a route map.

[NetworkGuy!]

Thanks