aggregate-address/attribute-map vs route-map's or prefix-lists

[mbellears2]

Just wondering if someone could please explain under what circumstances you would use aggregate-address/attribute-map vs route-map's or prefix-lists?

We are wanting to advertise our aggregate to multiple upstreams (Appending AS's to one to make it less attractive), and also some more specific /24's to "force" traffic destined to them to come in via a certain provider.

Thanks in advance.

[thisisshanky]

If you want to summarize all your networks into one, or a mix of summary and individual prefixes, you need to use the aggregate address command.

Route-maps / prefix-lists have a lot of applications, especially for route filtering. They are generally not used for aggregating routes to an upstream provider. Route-maps are also used to set a BGP attribute like community, weight, AS-path etc..

[mbellears2]

Ok - Historically, I have done this under BGP conf:

network xxx.xxx.x1.0

network xxx.xxx.x2.0

network xxx.xxx.x3.0

network xxx.xxx.x4.0

network xxx.xxx.x1.0 mask 255.255.240.0

neighbor Upstream1 peer-group

neighbor Upstream1 remote-as xxxxx

neighbor Upstream1 soft-reconfiguration inbound

neighbor Upstream1 route-map Upstream1-ADV out

neighbor Upstream1 route-map Upstream1_IN in

neighbor xxx.xxx.xxx.xxx peer-group Upstream1

Then,

route-map Upstream1-ADV permit 10

match ip address 80

set as-path prepend xxxx xxxx

access-list 80 permit xxx.xxx.x1.0 0.0.15.255

Would aggregate address be a more elegant solution in this situation?

[thisisshanky]

Route-maps does a totally different function than what aggregate-address do. Your route-map Upstream-ADV prepends ASPATH (probably to prefer one link over another). This function cannot be done using Aggregate address command. The soul purpose of aggregate address is to summarize networks (supernets). You are trying to compare two mutually exclusive commands.

[mbellears2]

I certainly appreciate your patience/assistance with this!

Ok - Can you not use attribute-map map_name within the aggregate-address, and then have a route-map pre-pending AS's etc?

I guess I'm just wondering if (In my situation) I should even be considering using aggregate-address? Or is my use of route-maps an acceptable solution?

Regards,

MB