Cisco 10720 Configuration Guide - Page 105

Chapter 4 Troubleshooting Basic Troubleshooting RPR-IEEE for the Uplink Card Verifying Clocking There are two modes of clocking for the rpr-ieee interface, LINE and INTERNAL. Clocking works over dark fiber. • 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. 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 Cisco 10720 Internet Router Installation and Configuration Guide 4-5