3Com MSR 30, MSR 20, MSR 50 manual Crossover Isdn S/T cable

138CHAPTER 3: MULTIFUNCTIONAL INTERFACE MODULES

When a BSV interface works in network mode, it uses a crossover ISDN S/T interface cable for connection, with pins 3 and 6 for data transmission and pins 4 and 5 for data receiving. At one end of the cable is an RJ-45 plug for connecting the BSV interface and at the other end of the cable is an RJ-45 receptacle for connecting a TE device.

Figure 158 Crossover ISDN S/T cable

Connecting the Interface Cable

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CAUTION:

■If outdoor cabling is involved, you need to install a special lightning arrester at the input end of the ISDN BRI S/T interface cable to avoid lightning strike.

■When connecting the interface cable, pay attention to the mark on the interface to avoid wrong insertion, which may damage the interface card or even the router host.

Step 1: Identify the operating mode of the BSV interface. If the interface is to be connected to an ISDN network, it should operate in user mode; if the interface is to be connected to a TE device, such as a digital phone or another BSV interface in user mode, the interface should operate in network mode.

Step 2: Connect the cable.

1To connect the module to an ISDN network, identify the type of the ISDN line provided by your telecommunications service provider.

■If it is an ISDN U interface line, use an NT1 for conversion. Insert one end of the S/T interface cable into the S/T interface on the NT1 and the other end to a BSV interface on the MIM-2BSV/MIM-4BSV.

■If it is an ISDN S/T interface line, directly connect the cable to a BSV interface on the MIM-2BSV/MIM-4BSV.

2To connect the module to a TE device, use a crossover S/T interface cable. Connect the RJ-45 plug at one end of the cable to the MIM-2BSV/MIM-4BSV interface, the RJ-45 receptacle to the straight-through S/T interface cable, and then the straight-through cable to the TE device.