[nanog] Connections among ASes (fwd)

Chengchen Hu huc at ieee.org
Fri Nov 30 02:49:13 UTC 2007

I agree that IXPs could be connected. Let me explain the problem more clear. Suppose the following example. ISP A has a router A1 in IXP1 and a router A2 in IXP2; and ISP B has a routers B1 in IXP1 and a router B2 in IXP2. It is possible that we have DIRECT link A1A2 and B1B2 to connnect two IXPs, but I don't think there may be DIRECT link like A1B2 or A2B1. Since it should be much cheaper and easier for ISP A and ISP B to be connnected in the same IXP using links like A1B1 or A2B2. Am I right?

So in your case, all the suppliers and peers DIRECTLY connected to any one of your routers are located in the same IXP?  

From: Tuc at T-B-O-H.NET
Data: 2007-11-29 19:29:12
To: huc at ieee.org
Subject: [nanog] Connections among ASes (fwd)

> Hi, 
> I am not sure about whether the following two conditions are true or not:
> 	1) there is no such a direct link between two routers located in two Internet eXchange Points-IXPs (even in same city) if they are from different ASes. For example, a router A belongs to AS x located in IXP1, and router B belongs to AS y located in IXP2, there is no link between A and B.
>     2) small AS will not use one router to connect to 2 different providers in differnet IXPs. It is much cheaper using one router to connect with different ASes in a same IXP. 


	Not quite sure I understand this... But, giving the old college try (Even though I didn't go
to college)...

	Just because someone is at an IX, doesn't mean they peer with EVERYONE on the IX. IX's can also be interconnected,
so even though ISP1 is at IX1 in 1 place, and ISP2 is at IX2 in place #2, they potentially COULD be interconnected but
don't HAVE to be. IX's inherently aren't interconnected, but there are some places where they are. NYIIX has 2 sites.
NYCX has 3. NYIIX and LAIX were supposed to be tied together, but not sure if it ever happened.

	As for small ISP with 1 router... When we were at the NYIIX, we had 1 router (Cisco 6509) and connected to 3
bandwidth suppliers AND ~40 peers at the NYIIX. We also had 2 routers, both were connected to each other, as well
as both to our suppliers + our Peers at the NYIIX peered at 2 addresses with us. We had redundant routers, so
never saw the need to split functionality apart.


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