GPN Topology

Each state has one or more well-defined unique Base VPs and Base VCs, called a BVP and BVC, respectively. Similarly, each router in a member state has a well-defined edge number EN, which is the BVC for the first listed device in the state. On the GPN side, each GPN router has a well-defined device number, called a DN. Then the (VP,VC) from a member router to a GPN router is defined as follows:

where BVP is the Base virtual path for the state, EN is the edge number for the member router, and DN is the device number of the GPN router. For example, in the diagram above (and in the tables below), the BVP for Arkansas is 172, the edge number for ua.r is 832, and the ks-2.r has device number 5. Therefore, the (VP,VC) pair is

This is the virtual circuit that ua.r expects to see for this device (and is essentially indepedent of the PVCs in the state network). Note that when the PVC actually hits the router, the VP (172 in this case) is stripped and set to 0. The following two tables define the BVP, BVC, DN, and EN numbers. The columns labelled BIP and EIP will be described below and deal with the IP subnets.

Note that in the above table, Kansas takes up two BVPs because of the number of connections from that state. Here is a table of GPN locations, devices, and device numbers. Again, the DIP relates to the IP subnets and will be explained later.

The IP subnet defined by the PVC from a member router to a GPN router, except in the case of ks-4.r, which is only used locally, is always a /30 subnet and is calculated as follows. The first two octets are always 164.113. Each member router has an associated EIP as in the tables above, always in the form x.y, and each GPN router has an associated DIP. The third octet of the subnet is x+DIP, and the forth octet is y. Hence the subnet between ua.r and ks-2.r, where the EIP is 1.64 and the DIP is 234, is

The member site router is always given the lower address, so the subinterface on ua.r has IP address 164.113.235.65 and the subinterface on ks-2.r has IP address 164.113.235.66.

The following table details all of this information.

ATM VC Plan

The following table describes the internal GPN PVCs and IP connections. Note that the VCD is not included in this table, since it is always the same as the interface number.

The next diagram illustrates the network layer of GPN, including many of the subnets. For simplicity, the point-to-points forming the full mesh between the routers is not shown. See the included tables for details.

GPN IP Layer and VLANs
ASN 11317

GPN IP Subnets

The following table describes the IP subnets in use by GPN.

GPN Loopback Addresses

The following table describes the Loopbacks in use by GPN.

GPN Ethernet VLANS and IP Addresses

The following table describes the Ethernet Subnets in use by GPN.

GPN IPv6 Subnets

The following table describes the IPv6 ranges in use by GPN. The range 2001:468:01FF::/48 includes the point to point links. If a site uses 2001:468:010X::/48 for internal addresses, then the point-to-point to that site is 2001:468:01FF:000X::/64, with 1 as the address on the GPN side, and 2 the address on the side fo the site.