[NANOG] Re: question about peering relationships

[Christopher Hawker via NANOG <nanog () lists nanog org>]

Yes, this is quite common - as an example, AS64505 can have AS64500 as a transit provider and peer with AS64510, and 
AS64510 can be a transit provider of AS64500, if that’s what you mean.

It's rather normal for this to happen, nothing out of the ordinary. AS64510 would only export their originating routes 
to an IX while sending their full table to transit customers. You could (or should) preference peering higher than 
transit to save on transit costs etc. but I digress...

Regards,
Christopher Hawker

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________________________________
From: Sriram, Kotikalapudi (Fed) via NANOG <nanog () lists nanog org>
Sent: Monday, April 7, 2025 11:15 pm
To: nanog () nanog org <nanog () nanog org>
Cc: Sriram, Kotikalapudi (Fed) <kotikalapudi.sriram () nist gov>
Subject: [NANOG] question about peering relationships

Does the following ever happen in reality? Do you think it is strange and unlikely?

The lateral (i.e., non-transit) peer of an AS is also the transit provider of the AS's transit provider.  Example: AS A 
has AS B as a transit provider and AS C as a lateral peer, and AS C is a transit provider of AS B.

Thank you.

Sriram


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