Using loopback commands – Cisco 7300-6T3 User Manual
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Clear Channel 6-Port T3 (DS3) Line Card Installation and Configuration
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Chapter 4 Configuring the 6T3 Line Card
Checking the Configuration
Using the ping Command to Verify Network Connectivity
Using the ping command, you can verify that an interface port is functioning properly. This section
provides a brief description of this command. Refer to the publications listed in the
Documentation” section on page viii
for detailed command descriptions and examples.
The ping command sends echo request packets out to a remote device at an IP address that you specify.
After sending an echo request, the system waits a specified time for the remote device to reply. Each
echo reply is displayed as an exclamation point (!) on the console terminal; each request that is not
returned before the specified timeout is displayed as a period (.). A series of exclamation points (!!!!!)
indicates a good connection; a series of periods (.....) or the messages [timed out] or [failed] indicate a
bad connection.
Following is an example of a successful ping command to a remote server with the address 10.0.0.10:
Router# ping 10.0.0.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 10.0.0.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/15/64 ms
Router#
If the connection fails, verify that you have the correct IP address for the destination and that the device
is active (powered on), and repeat the ping command.
Proceed to the next section, “
,” to finish checking network connectivity.
Using loopback Commands
With the loopback test, you can detect and isolate equipment malfunctions by testing the connection
between the 6T3 line card interface and a remote device such as a modem or a CSU/DSU. The loopback
command places an interface in loopback mode, which enables test packets that are generated from the
ping command to loop through a remote device or compact serial cable. If the packets complete the loop,
the connection is good. If not, you can isolate a fault to the remote device or compact serial cable in the
path of the loopback test.
provides examples of the loopback {dte | local | network {line | payload} | remote}
command. The examples given are for interface 0 of a 6T3 line card in slot 2 of a Cisco 7304 router:
Table 4-8
Using loopback Commands
Command
Function
Example
loopback local
Sets the interface into local loopback
mode. Local loopback loops the router
output data back toward the router at the
framer.
Router(config)# interface serial 2/0
Router(config-if)# loopback local
loopback network line
Sets the interface into network line
loopback mode. Network line loopback
loops the data back toward the network
(before the framer).
Router(config)# interface serial 2/0
Router(config-if)# loopback network
line