Verifying Clocking; Pass-Thru Mode; Verifying The Pass-Thru Mode - Cisco 10720 - Internet Router Installation And Configuration Manual

Chapter 4 Troubleshooting

Verifying Clocking

There are two modes of clocking for the rpr-ieee interface, LINE and INTERNAL. Clocking works over
dark fiber.
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Ideal clocking is achieved when all interfaces have the clocking set to INTERNAL. The following
example shows this configuration:
router(config)# interface rpr-ieee 1/1
router(config-if)# rpr-ieee clock-source internal East
router(config-if)# rpr-ieee clock-source internal West

PASS-THRU Mode

The rpr-ieee line card acts as an optical regenerator when it is operating in PASS-THRU mode.
PASS-THRU mode isolates the node. This mode is activated when the interface is placed in shutdown
mode, or the node is not receiving layer 2 keepalives on span East or span West.
Use the shutdown interface configuration command to place the router rpr-ieee interface in
PASS-THRU mode.
PASS-THRU mode is a useful troubleshooting tool for isolating which node on the ring is faulty.
The following example shows sample output from this command:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#interface RPR-IEEE 1/1
Router(config-if)#shutdown
Router(config-if)#end
Router#
3d06h: %SYS-5-CONFIG_I: Configured from console by tty1
3d06h: %LINK-5-CHANGED: Interface RPR-IEEE1/1, changed state to administratively down
3d06h: %LINEPROTO-5-UPDOWN: Line protocol on Interface RPR-IEEE1/1, changed state to down

Verifying the PASS-THRU Mode

Use the show rpr-ieee ips EXEC command to verify that the rpr-ieee node is in PASS-THRU mode,
which occurs when the interface is administratively down.
The following example shows sample output from this command:
Router# show rpr-ieee protection
RPR-IEEE1/1 is administratively down
Router#
78-13062-10
INTERNAL means that the rpr-ieee interface uses its internal 20ppm or Stratum-3 clock. LINE
means it takes timing from the other span of the line.
Having both spans with clocking set to INTERNAL is the default configuration and results in normal
operation.
Having both spans with clocking set to LINE is not advised and will result in bit interleaved parity
(BIP) errors over time.
Pairing opposite spans of a connection with one spans INTERNAL and one span LINE is acceptable,
but not necessary.
Basic Troubleshooting RPR-IEEE for the Uplink Card
Cisco 10720 Internet Router Installation and Configuration Guide
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