question about AS relationship

Mark Tinka mark.tinka at
Fri Feb 21 05:50:38 UTC 2014

On Friday, February 21, 2014 07:37:52 AM Song Li wrote:

> Thanks. In order to prevent route leaking, this
> imformation should be provided to providers.

Route leaking is not only from customers-to-providers. It 
can also be from providers-to-providers (and from peers-to-

The majority of leaks I've seen in the past have been 
possible because some inter-provider links have not been 
filtered correctly, i.e., they are providing (unknown) 
transit where they would only be peering.

It is not uncommon to see more relaxed filtering between 
providers/peers, e.g., AS_PATH-based only, max-prefix-based 
only, e.t.c., but please don't send these out to anyone else 
besides your customers unless the ultimate relationship 
calls for it. Of course, one can't guarantee that the 
customers you send this to won't leak it to their own 
transit providers.

Bottom line, chasing route leaks can be a full time job.

> but another question, should the AS relationships between
> customer and its other neighbors (downstrem/peer/another
> provider)  be private?

What do you mean, in terms of how they connect or in terms 
of the business relationship?

I don't think it matters either way. The common peering, 
filtering and re-announcement rules apply.

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