ii
POS interface configuration example ·························································································································· 25
Directly connecting routers through POS interfaces ·························································································· 25
Connecting routers through POS interfaces across frame relay ······································································· 25
Troubleshooting POS interfaces ···································································································································· 27
Configuring CPOS interfaces ···································································································································· 28
Overview ········································································································································································· 28
SONET···································································································································································· 28
SDH ········································································································································································· 28
CPOS ······································································································································································ 28
SDH frame structure ·············································································································································· 28
Terms ······································································································································································· 29
Multiplexing E1/T1/E3/T3 channels to form STM-1 ························································································ 29
Calculating E1/T1/E3/T3 channel sequence numbers ···················································································· 31
Overhead bytes ····················································································································································· 32
CPOS interface application scenario ·················································································································· 33
Configuring a CPOS interface ······································································································································ 34
Configuring an E1 channel ··········································································································································· 35
Configuring a T1 channel ············································································································································· 36
Configuring an E3 channel ··········································································································································· 37
Configuring a T3 channel ············································································································································· 38
Displaying and maintaining CPOS interfaces ············································································································ 39
CPOS interface configuration example ······················································································································· 39
Troubleshooting CPOS interfaces ································································································································· 41
Interface physical status is up, link protocol status is down, and loopback is detected ································ 41
Configuring E-CPOS interfaces ································································································································· 42
Overview ········································································································································································· 42
SONET···································································································································································· 42
SDH ········································································································································································· 42
E-CPOS ··································································································································································· 46
Configuring an E-CPOS interface ································································································································· 47
Configuring an E-CPOS interface ························································································································ 47
Configuring the operating mode of an E-CPOS interface/channel ································································· 48
Displaying and maintaining E-CPOS interfaces ········································································································· 52
E-CPOS interface configuration example ···················································································································· 52
Troubleshooting E-CPOS interfaces ······························································································································ 55
Symptom ································································································································································· 55
Solution ··································································································································································· 55
Configuring Loopback and null interfaces ··············································································································· 56
Loopback interface ························································································································································· 56
Introduction ···························································································································································· 56
Configuring a loopback interface ······················································································································· 56
Null interface ·································································································································································· 57
Introduction ···························································································································································· 57
Configuring interface Null 0 ································································································································ 57
Displaying and maintaining loopback and null interfaces ························································································ 58
Index ··········································································································································································· 59
