5. Private Peering Inclination Signals a More Attractive Peer.

a. The “Big Players” privately peer with each other, and some even loath Public Peering fabrics for historical reasons. Adopting this attitude puts one in the company of the largest Tier 1 ISPs in the world. “For certain very large networks, Public Peering makes no sense at all. For certain very small networks, Public Peering may make perfect sense.” Or put more harshly, “if you think that Public Peering is a good idea, you’re just not large enough yet.”

Three Key Points about Internet Peering

Three key points often get lost when one is first introduced to Internet Peering. It is worth reading the following points a few times:

• Internet Peering is not a transitive relationship. The fact that WestNet is peering with MidNet and MidNet is peering with EastNet does not imply that EastNet customers can reach WestNet customers. WestNet knows how to get to only its own and MidNet’s customers, and EastNet knows how to reach only its own and MidNet’s customers. The fact that they both peer with MidNet is inconsequential; peering is a nontransitive relationship.
• As such, Internet Peering is not a perfect substitute for Internet Transit. Internet Transit is a service that provides access to the global Internet, while Internet Peering simply provides a more direct path for a subset of the traffic.
• Internet Peering is typically settlement-free, with each side deriving about the same value from the reciprocal arrangement. If either party perceives that the benefit derived from peering is asymmetric, one party or the other may deny peering or suggest an alternative paid arrangement.

Route Announcements

Routing announcements are the mechanism for propagating reachability information between networks, and we use the color and/or the name of the network to graphically (Figure 11-3) represent these announcements.

Note that the solid black marker in the routing announcement indicates a default route, the route that can be used to reach any destination in the Internet.