I'm puzzled by one aspect on the implementation.. how to build your customer prefix filters.. that is, we have prefix-lists for prefix and length. Therefore at present we can only accept a tagged route for a whole block.. not good if the announcement is a /16 etc !
MCI handles this by only filtering on prefix, not length. Well, allowing you to only announce up to your length, not shorter, but longer is allowed.
Hmm not keen, have moved acl->prefix w/len to stop folks from doing this, in addition we have an extra filter which overrides anything that would deny anything longer than a /24. I'm not keen to change that.. LART appears to have little or no effect with my customers, preemption appears to be the only way! Steve
Now, I could do as per the website at secsup.org which means we have a route-map entry to match the community before the filtering .. but that would allow the customer to null route any ip.
What we need is one to allow them to announce any route including more specifics of the prefix list - how are folks doing this?
It's not hard. I think the old UUNET just used standard ACLs (1->99). :) But with prefix filters, you can set gt & lt prefix lengths on the filters trivially.
Of course, your customers can then deaggregate to their hearts content. If they do, you should hunt them down and LART them. But it is useful for some things, especially when combined with no_export, the black-hole communities, or other communities.