Approximate backbone topologies of the largest Internet providers
together with geographical locations of the POPs and Exchanges,
and approximate long-distance link delays.
The models contain fully configured routers that run BGP4 (external
and internal) and OSPFv2. Two or more geographically overlapping backbones
can be configured to peer at the specified peering locations.
These models can be easily further elaborated by attachment of customer networks
at distinct POPs, either for the studies of routing, or to study the traffic,
The topology diagrams below roughly preserve the relative geographic
locations of major routers; but "lift" one network above another in order
to illustrate the BGP peering links. In reality, the peering routers
usually sit one next to another in an Internet Exchange or a peering hotel.