Specifications

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Cisco 7100 Series VPN Router Installation and Configuration Guide
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Chapter 4 Performing a Basic Startup Configuration
Configuring a Router
Step 4 Enable the interface.
Router(config-if)# no shutdown
Step 5 Configure additional interfaces as required.
Step 6 Press Ctrl-Z (hold down the Control key while you press Z) or enter end to exit configuration mode
and return to the EXEC command interpreter.
Step 7 Save the configuration to NVRAM as follows:
Router# copy running-config startup-config
[OK]
(See the “Saving the Running Configuration to NVRAM” section on page 4-17. Also see the “Checking
the Interface Configurations” section on page 4-18 for examples of interface configurations.)
Configuring the T1 and E1 Interfaces
The Cisco 7120-4T1 provides four channel-independent, synchronous serial ports that support
full-duplex operation at T1 (1.544-Mbps) and E1 (2.048-Mbps) speeds. The default settings and the
commands to change the defaults are listed in Table 4-2.
Perform a basic interface configuration using the procedure below.
Note Additional configuration commands may be required, depending on your system requirements and the
protocols you plan to route on the interface.
At any time, you can exit the privileged level and return to the user level by entering disable at the
prompt as follows:
Router# disable
Step 1 At the Router (config)# prompt, enter the interface type slot/port command to enter the interface
configuration mode. In this example, the serial port 0 is configured:
Router(config)# interface serial 1/0
Router(config-if)#
Enter any changes to the configuration.
Table 4-2 T1 and E1 Interface Defaults
Attribute Default Value Command
Duplex mode Full duplex half duplex
Clock rate Uses the external
timing signal
clock rate
Invert clock rate Not inverted invert-txc
NRZI encoding NRZ format nrzi-encoding
CRC 32 16 bits crc size (16 or 32 bits)