Cabling a Router to the Big Frame Relay Switch

Cabling a Router to the Big Frame Relay Switch

To make Frame Relay work, each router needs a physical cable between itself and a device called a Frame Relay switch. The telco uses Frame Relay switches in its local central offices (COs) that together switch the data to the correct sites. Like a PC attaches to a LAN switch with an Ethernet cable, a router needs a physical connection to a Frame Relay switch to use Frame Relay.

When a router physically connects to a Frame Relay switch, it is connecting to a Frame Relay service. The company that sells Frame Relay services is called a Frame Relay service provider. Often, a Frame Relay service provider is also a telco, but in most cases, that company works with other telcos to create the Frame Relay network. The service that the provider is selling is the ability for a router to send a Frame Relay frame and have it be delivered to another router that is also connected to the same Frame Relay network.

To create the physical connection between a router and the Frame Relay service provider, the provider needs to run a cable from all your sites to their local COs. Sound familiar? It should. Frame Relay is a set of protocol specifications, all matching the functions of OSI Layer 2. For Layer 1 functionsthings like the cabling and how the bits are actually transmitted over the wireFrame Relay uses the same standards that serial links do, as shown in Figure 15-1.