In message <m0tPwiv-000Nj8C@aero.branch.com>, Jon Zeeff writes:
Depends on the situation as to whether it's detrimental. Proxy-aggregation , as this is called, can alter traffic patterns in dual-homed situations. Th e change is not always bad, though it is often un-desirable.
In general, proxy-aggregation is good for everybody.
If we had a good method for people to indicate routes that they didn't want t o be aggregated, then more proxy aggregation could be done safely.
One way is to register an aut-num if the routes are in a separate AS and correctly indicate what other AS you peer with so others know there are backup paths which are going to have to still work after aggregation is done and not become primary paths. If you don't have an AS then register the route in all the AS you are multihomed to, not just one of them. This is gross, but I don't see a good way around it. In short, the only reason not to aggregate is to preserve correct routing for a dual homed situation (or properly indicate a hole). The means to indicate this is by properly registering the information in the IRR. Then hope the proxy aggregator bothers to look there, but if they don't then you have grounds to yell at them. Otherwise, they can just shrug. Curtis