Cisco 2525 Betriebsanweisung PDF herunterladen (Seite 27)

Preparing to Install the Cisco 2524 and Cisco 2525 Routers 2-13

Preparing to Connect to a Network

Table 2-4 ISDN BRI Cable Speciﬁcations

Synchronous Serial Connections

The serial port on the ﬁve-in-one synchronous serial WAN module is a 60-pin, D-type

connector. The synchronous serial port (except the EIA-530) can be conﬁgured as DTE or

DCE, depending on the attached cable. All DTE serial ports require external clocking from

a DSU/CSU or other DCE device.

You must use a special serial cable to connect the router to a modem or DSU/CSU. This

cable is available from Cisco and is usually ordered with the system. The cable uses a

DB-60 connector on the chassis end. See the appendix “Cabling Speciﬁcations for the

Cisco 2524 and Cisco 2525 Routers” for cable pinouts. For ordering information, contact a

customer service representative.

Note Because of the small size of the pins on the DB-60 serial connector, attempting to

manufacture your own serial cables is not recommended.

As with all signaling systems, EIA/TIA-232 signals can travel a limited distance at any

given bit rate; generally, the slower the data rate, the greater the distance. Table 2-5 shows

the standard relationship between baud rate and maximum distance.

1. nF = nanoFarad.

Speciﬁcation High-Capacitance Cable Low-Capacitance Cable

Resistance (at 96 kHz) 160 ohms/km 160 ohms/km

Capacitance (at 1 kHz) 120 nF

/km 30 nF/km

Impedance (96 kHz) 75 ohms 150 ohms

Wire diameter 0.024" (0.6 mm) 0.024" (0.6 mm)

Distance limitation 32.8' (10 m) 32.8' (10 m)

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Cisco 2525 Betriebsanweisung Seite 27