Interconnection Plan
ATM Connectivity
MAGIC and AAI are already interconnected at the Sprint TIOC. ATM switches in the two networks exchange ATM-level routing information, making the two networks effectively a single ATM network. An end system attached to either network can open a VCC to any other end system attached to either network.
There are links which connect ATM switches belonging to the vBNS and AAI, via an ATM switch at SDSC (see Figure 1 ). There is no exchange of ATM-level routing information, however, leaving the vBNS as a separate ATM network.
No new ATM links are required to interconnect the three networks, but it is necessary to perform some further configuration (e.g. establishing PVCs or PVPs) to allow cells to flow.
IP Connectivity
There is currently no direct IP connectivity between the three networks. Table 1 shows the IP network numbers used by each network.
While MAGIC and AAI effectively run on the same ATM network, they comprise seperate Logical IP Subnets (LISs). There is no routing of IP packets between hosts on the two networks. If a host on MAGIC needs to communicate with a host on AAI, it is usually configured as an AAI host. This involves:
- Giving the host an AAI IP address,
- Configuring the host to use the AAI ATMARP server,
- Installing interface routes on the host to AAI networks other than the one its AAI IP address is part of.
Packets from the vBNS are not currently routed directly to either MAGIC or AAI. In order to enable routing between the two networks, there must be an exchange of IP-level routing information between them. The natural choice for this exchange would be to establish a connection between the I-DREN and vBNS routers at SDSC using an exterior gateway protocol such as BGP4.
Interconnection Options
There are two main approaches to interconnecting the networks:
An ATM-level connection would connect one or more of the vBNS's ATM switches to MAGIC/AAI ATM switches. The switches would exchange ATM-level routing information. ATM VCCs could be established between any two end systems attached to the three networks.
An IP-level connection would connect a vBNS router to a MAGIC/AAI router. The routers would exchange IP-level routing information (e.g. via BGP4). IP datagrams could be exchanged between the routers, but no end-to-end ATM VCCs would exist. As shown in Figure 1 , the routers in this case could communicate via either FDDI or ATM. IP-level connection was chosen as the most practical way to achieve the interconnection.
Figure 1 shows the paths at SDSC between AAI and the vBNS. SDSC has both a vBNS node and a connection to the Interim Defense Research and Engineering Network (I-DREN). The I-DREN router at SDSC has potential ATM connectivity to AAI via an ATM switch at NCCOSC, but is not part of any AAI IP network.
The interconnection of the networks was discussed on a conference call in late August 1997 and via email and the following options were explored:
- Configure SDSC's router as an AAI node and have it and the vBNS router provide connectivity by routing over the DMZ FDDI ring.
- Configure the I-DREN as an AAI node and have it and the vBNS router provide connectivity by routing over the DMZ FDDI ring. This step was to be an intermediate step to 3 before the ATM connection between the SDSC and vBNS ATM switches was in place,
- Use the I-DREN and vBNS routers to provide connectivity by routing over a PVC between the SDSC and vBNS ATM switches,
- Configure the vBNS router as an AAI network node and provide single-hop routing between hosts on the three networks.
The consensus of the group was that no. 2 was the preferred option in the absence of a direct connection between the SDSC and vBNS ATM switches but that no. 3 was preferred. For no. 3 , the following work items must be accomplished:
- Allocate an AAI IP address for the I-DREN router and configure the router with the IP address and the AAI ATMARP server address,
- Configure a PVC between the I-DREN and vBNS routers,
- Allocate IP addresses for the ATM connection between the I-DREN and vBNS routers,
- Configure the I-DREN router to announce AAI IP network numbers to the vBNS router and accept vBNS routes from the vBNS router; configure the vBNS router to announce vBNS IP network numbers to the I-DREN router and accept AAI routes from the I-DREN router,
- Configure MAGIC hosts as nodes on AAI. The hosts which have been identified are Iss-1.sri.magic.net, Blackstone.tioc.magic.net, and Iss-1.edc.magic.net,
- Configure hosts at EDC, SRI, the TIOC, and NAVO Stennis to use the I-DREN router to reach destinations on the vBNS.
Initially, connectivity will be established via method no. 3 , but will be changed to no. 4 as circumstances permit, since this results in one fewer hop between the networks, and fewer administrative bodies need to be involved.