Cisco 15327 - Manual (Page 88)

5-8
Ethernet Card Software Feature and Configuration Guide, R7.2
Chapter 5 Configuring POS
C2 Byte and Scrambling
To configure path alarms as triggers and specify a delay, perform the following steps beginning in global
configuration mode:
C2 Byte and Scrambling
One of the overhead bytes in the SONET/SDH frame is the C2 byte. The SONET/SDH standard defines
the C2 byte as the path signal label. The purpose of this byte is to communicate the payload type being
encapsulated by the SONET framing overhead (FOH). The C2 byte functions similarly to EtherType and
Logical Link Control (LLC)/Subnetwork Access Protocol (SNAP) header fields on an Ethernet network;
it allows a single interface to transport multiple payload types simultaneously. The C2 byte is not
configurable.
Table 5-5 provides C2 byte hex values.
Command Purpose
Step 1 Router(config)# interface pos
number
Enters interface configuration mode and specifies the POS
interface to configure.
Step 2 Router(config-if)# pos trigger
defect {all | ber_sf_b3 | encap
| pais | plop | ppdi | pplm |
prdi | ptim | puneq }
Configures certain path defects as triggers to bring down the
POS interface. The configurable triggers are as follows:
• all—All link down alarm failures
• ber_sd_b3—PBIP BER in excess of SD threshold
failure
• ber_sf_b3—PBIP BER in excess of SD threshold failure
(default)
• encap—Path Signal Label Encapsulation Mismatch
failure (default)
• pais—Path Alarm Indication Signal failure (default)
• plop—Path Loss of Pointer failure (default)
• ppdi—Path Payload Defect Indication failure (default)
• pplm—Payload label mismatch path (default)
• prdi—Path Remote Defect Indication failure (default)
• ptim—Path Trace Indicator Mismatch failure (default)
• puneq—Path Label Equivalent to Zero failure (default)
Step 3 Router(config-if)# pos trigger
delay millisecond
Sets waiting period before the line protocol of the interface
goes down. Delay can be set from 200 to 2000 ms. If no time
intervals are specified, the default delay is set to 200 ms.
Step 4 Router(config-if)# end Returns to the privileged EXEC mode.
Step 5 Router# copy running-config
startup-config
(Optional) Saves configuration changes to NVRAM.
Table 5-5 C2 Byte and Scrambling Default Values
Signal Label SONET/SDH Payload Contents
0x01 LEX Encapsulation with 32-bit CRC with or without scrambling
0x05 LEX Encapsulation with 16-bit CRC with or without scrambling
0xCF Cisco HDLC or PPP/BCP without scrambling