What is multi-homing and why should my ISP have it?

Multi homing means that your ISP is connected to more than one Internet backbone. He has more than one independent path to any particular destination and his router chooses the quickest path for every individual site. To perform this task, Cybercom’s router must be able to store the entire Internet routing table for each backbone to which he is connected. It must also be able to rapidly recompute optimum routes in the event of changes in network conditions. You want it because it means that in the event of a failure of a route to any particular destination or an entire Internet backbone or Cybercom's connection to that backbone, your traffic will still get to its destination, via the other backbone(s). Even without failures, it enables Cybercom to select the best route to use to any particular destination. For example, suppose that you wanted to send some traffic from College Station to Little Rock. One of the backbone connections has a route to Little Rock via San Francisco while the other backbone has a direct route to through Dallas. Even though all the rest of his traffic uses the first backbone, your traffic can take the shorter route via the second backbone. Cybercom currently maintains a full T1 connection to both the Sprint and MCI Internet backbones.

What is symmetrical multi-homing and why should my ISP have it?

Symmetrical multi-homing means that the alternate paths from the ISP to the various internet backbones are the same speed. That is, two or three T1’s, two or three T3’s, etc. Not a T1 and a fractional T1. If your ISP has unbalanced pipe sizes, or both pipes connect to the same backbone, he loses the advantages of multi-homing. The fractional T1 can not handle the traffic which is normally flowing over the full T1 and in the event of a failure, some or all of the ISP’s traffic must be discontinued.

Why aren't all ISP's multi-homed?

Cost is one factor. Aside from the cost of the multiple backbone connections, the router necessary for acceptable performance under multi-homed conditions costs several times more than the low end router typically used by a single homed ISP. Another reason is the technical expertise necessary to manage the multiple connections and the software protocol (called BGP-4) necessary to live in a multi-homed environment.

For further information contact:

Cybercom Corporation
416 Tarrow Drive
College Station, TX 77840
409.268.6800 Sales
409.268.0771 Service
409.260.2652 Fax
web: www.txcyber.com
email: www@txcyber.com