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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 20 Checking Status and Connectivity
Checking the 10-Gigabit Ethernet Link Status
Checking the 10-Gigabit Ethernet Link Status
Cable diagnostics allow you to activate the pseudorandom binary sequence (PRBS) test on the
10-Gigabit Ethernet links.
Note
The PRBS test is currently available on the 1-port 10GBASE-E serial 10-Gigabit Ethernet module
(WS-X6502-10GE).
To run the PRBS test between two devices, you must start it on both ends of the cable. If the cable is looped
back, a single end can generate the test sequence (on the Tx), verify the test sequence, and count the errors
(at the Rx).
Before the PRBS test starts, the port is automatically put in the errdisable state. The errdisable timeout
is disabled for the port so that the port is not automatically reenabled after the timeout interval ends. The
errdisable timeout is automatically reenabled on the port after the PRBS test finishes.
When the PRBS test is running, the system does not allow you to enter the
set port enable
and
set port
disable
commands.
The PRBS error counter measures the reliability of the cable. The error counter range is from 0–255. A
value of 0 signifies a perfect link connection; a value of 255 signifies that the port is faulty, not
connected, or that there is no communication through the link. If the counter does not remain at 0 for a
predetermined length of time, the link is faulty. For example, for a baud error rate (BER) of 10^-12, the
counter should remain at 0 for 100 seconds.
Each time that you access the PRBS counter by entering the
show port prbs
command, the PRBS error
counter value is reset to 0, and the counter begins to accumulate errors again.
Note
The PRBS counter is a “read and clear” register. The first reading in a sequence is usually unreliable and
serves primarily to purge the counter; successive readings are accurate.
To start or stop the PRBS test, perform this task in privileged mode:
This example shows how to start the PRBS test on port 1 on module 5:
Console> (enable)
test cable-diagnostics prbs start 5/1
PRBS cable-diagnostic test started on port 5/1.
Console> (enable)
This example shows how to stop the PRBS test on port 1 on module 5:
Console> (enable)
test cable-diagnostics prbs stop 5/1
PRBS cable-diagnostic test stopped on port 5/1.
Console> (enable)
This example shows the message that displays when the PRBS test is not supported on a module:
Console> (enable)
test cable-diagnostics prbs start 6/1
Feature not supported on module 6.
Task
Command
Step 1
Start or stop the PRBS test.
test cable-diagnostics prbs
{
start
|
stop
}
mod/port
Step 2
Display the PRBS test counter
information.
show port prbs
