Routers and ISDN BRI connections / Routers and DSL connections / Routers and cable connections

Routers and ISDN BRI connections
5.2.4 This page will help students understand ISDN BRI connections.


With ISDN BRI, two types of interfaces may be used, BRI S/T and BRI U. Determine who is providing the Network Termination 1 (NT1) device in order to determine which interface type is needed.

An NT1 is an intermediate device located between the router and the service provider ISDN switch. The NT1 is used to connect four-wire subscriber wiring to the conventional two-wire local loop. In North America, the customer typically provides the NT1, while in the rest of the world the service provider provides the NT1 device.

It may be necessary to provide an external NT1 if the device is not already integrated into the router. Reviewing the labeling on the router interfaces is usually the easiest way to determine if the router has an integrated NT1. A BRI interface with an integrated NT1 is labeled BRI U. A BRI interface without an integrated NT1 is labeled BRI S/T. Because routers can have multiple ISDN interface types, determine which interface is needed when the router is purchased. The type of BRI interface may be determined by looking at the port label. To interconnect the ISDN BRI port to the service-provider device, use a UTP Category 5 straight-through cable.

Routers and DSL connections
5.2.5 This page describes routers and DSL connections.


The Cisco 827 ADSL router has one asymmetric digital subscriber line (ADSL) interface. To connect an ADSL line to the ADSL port on a router, do the following:

• Connect the phone cable to the ADSL port on the router.

• Connect the other end of the phone cable to the phone jack.

To connect a router for DSL service, use a phone cable with RJ-11 connectors. DSL works over standard telephone lines using pins 3 and 4 on a standard RJ-11 connector.

The next page will discuss cable connections.

Routers and cable connections
5.2.6 This page will explain how routers are connected to cable systems.


The Cisco uBR905 cable access router provides high-speed network access on the cable television system to residential and small office, home office (SOHO) subscribers. The uBR905 router has a coaxial cable, or F-connector, interface that connects directly to the cable system. Coaxial cable and an F connector are used to connect the router and cable system.

Use the following steps to connect the Cisco uBR905 cable access router to the cable system:

• Verify that the router is not connected to power.

• Locate the RF coaxial cable coming from the coaxial cable (TV) wall outlet.

• Install a cable splitter/directional coupler, if needed, to separate signals for TV and computer use. If necessary, also install a high-pass filter to prevent interference between the TV and computer signals.

• Connect the coaxial cable to the F connector of the router. Hand-tighten the connector, making sure that it is finger-tight, and then give it a 1/6 turn with a wrench.

• Make sure that all other coaxial cable connectors, all intermediate splitters, couplers, or ground blocks, are securely tightened from the distribution tap to the Cisco uBR905 router.