bgp aggregate-address

[brunop]

If I am using the bgp 'aggregate-address' command do I need a network statement?

From testing, it does not appear to be necessary but is this good/bad practice?

Below is my proposed configuration, any suggestions you can share would be appreciated.

!

router bgp 65000

no synchronization

bgp log-neighbor-changes

aggregate-address 10.0.0.0 255.255.0.0 summary-only

redistribute ospf 1

neighbor 10.255.0.1 remote-as 65111

maximum-paths 5

no auto-summary

!

[Pavel Bykov]

Just like Jon confirmed, you do not need a network statement, but you do need a subnet from that range in the routing table.

But then you don't need "summary-only" keyword either.

For example if you would have the following config:

aggregate-address 10.0.0.0 255.255.0.0

network 10.0.10.0 mask 255.255.255.0

network 10.0.20.0 mask 255.255.255.0

Then router would advertise:

10.0.0.0/16

10.0.10.0/24

10.0.20.0/24

And if you would use summary-only in this case, like this:

aggregate-address 10.0.0.0 255.255.0.0 summary-only

network 10.0.10.0 mask 255.255.255.0

network 10.0.20.0 mask 255.255.255.0

Than the router would only advertise 10.0.0.0/16. The routes 10.0.10.0/24 and 10.0.20.0/24 would be SUPPRESSED, and not advertised to neighbors.

[Jon Marshall]

Hi

You do not need a network statement to advertise out an aggregate address. As long as one of the networks that makes up the aggregate address is in the BGP table then the aggregate address will be advertised out.

HTH

Jon