Samantha Lo wrote:
Thank you so much for your prompt reply and the suggested setup. I think the setup should be adequate for our experiments, except that for a given prefix we generally need to advertise the prepended routes to some (e.g., 1) upstream ASs and unprepended routes to others. Can the setup that you suggested enable us to do that (through an access list, or different peer sessions, or community but which is not supported by the announcer you provided, or peer to more than one RRC)?
Unfortunately, it seems to me that this cannot be done as I suggested. The announcer is flexible enough to announce different AS-paths for different peers. However, since these routes will be announced to the same RRC, it doesn't matter what you announce, because the RRC will perform route selection and only announce one AS-path to all its upstreams. I have been trying to think of a solution that does not require modifying the RRC's configuration in a non-trivial way, but the only thing that comes to mind is that you do the different prepending with two different prefixes, which is not particularly realistic. We could of course set up multiple IBGP peerings between you and multiple RRCs, but the problem with that are that the RRCs are in different locations and have different transit providers. I don't know if this is adequate for your experiments. What would you suggest?
In the meantime, we will set up a BGP speaker here with the announcer. But if the announcer is not adequate for announcing prefixes with different prepending lengths to different upstream ASs, we may need to use some software routers.
Unfortunately, the announcer is not the problem here because it doesn't peer directly with our upstreams but would go through the RRC, which performs route selection. What did you have in mind?
We are planning to submit a paper to the IMC conf, and the deadline is late May. If you are interested, you are welcome to join our work.
I would definitely be interested to know what you have in mind. I have read the two-page abstract, but I don't really understand, for example, how this is different from the work you presented at NOMS 2004? (I was in the same session, presenting IPv6-in-IPv4 tunnel discovery...) Regards, Lorenzo -- Lorenzo Colitti lorenzo@ripe.net Network Engineer +31-20-5354471 RIPE NCC www.ripe.net