Troubleshooting guide

9-12
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 9 Troubleshooting CES Connections and Network Clocking
Troubleshooting Network Clocking
Checking the CES Interface Clocking Configuration
The clocking configuration of a CES interface might affect the traffic flow on the circuit. If quality of
the transmission has degraded, follow these steps to troubleshoot the CES interface clocking for
unstructured services:
Step 1 Check the Underflow and Overflow fields. Use the show ces interface command to display the network
clocking configuration:
Switch# show ces interface cbr 3/1/0
Interface: CBR3/1/0 Port-type:E1-120ohms-DCU
IF Status: UP Admin Status: UP
Channels in use on this port: 1
LineType: E1_LT LineCoding: HDB3 LoopConfig: Payload
SignalMode: NoSignalling XmtClockSrc: network-derived
DataFormat: Structured AAL1 Clocking Mode: Synchronous LineLength: 330_440
e1InternationalBits 0x3, e1NationalBits 0x1F, e1MultiFrameBits 0xB
LineState: RcvAIS LoopbackState
Errors in the Current Interval:
PCVs 0 LCVs 0 ESs 0 SESs 0 SEFSs 0
UASs 0 CSSs 0 LESs 0 BESs 0 DMs 0
Errors in the last 24Hrs:
PCVs 0 LCVs 0 ESs 0 SESs 0 SEFSs 0
UASs 0 CSSs 0 LESs 0 BESs 0 DMs 0
Input Counters: 0 cells, 0 bytes
Output Counters: 0 cells, 0 bytes
Step 2 Check the AAL1 Clocking Mode field. Use the ces aal1 clock command to modify the clocking mode
to adaptive. Adaptive clocking does not require an external clock source. If the problem ceases when
the clocking mode is changed from synchronous to SRTS, the reference clock is the problem.