13-6
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide
OL-14127-08
Chapter 13 Configuring the POS SPAs
Configuration Tasks
Modifying the CRC Size
CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted
data. The CRC size indicates the length in bits of the FCS.
The CRC size must be configured to be the same on both ends of the POS link.
To modify the CRC size, use the following command in interface configuration mode:
To return to the default CRC size, use the no form of the command.
Verifying the CRC Size
To verify the CRC size, use the show interfaces pos privileged EXEC command and observe the value
shown in the “CRC” field.
The following example shows that the CRC size is 16 for interface port 0 on the POS SPA installed in
subslot 0 of the SIP that is located in chassis slot 2 of the Cisco ASR 1000 Series Router:
Router# show interfaces pos 2/0/0
Hardware is Packet over Sonet
Internet address is 10.1.1.2.1
MTU 9216 bytes, BW 622000 Kbit, DLY 100 usec reliability 255/255, txload 1/255, rxload
1/255
Encapsulation HDLC, crc 16, loopback not set
Modifying the Clock Source
A clock source of internal specifies that the interface clocks its transmitted data from its internal clock.
A clock source of line specifies that the interface clocks its transmitted data from a clock recovered from
the line’s receive data stream.
For information about the recommended clock source settings for POS router interfaces, refer to
Configuring Clock Settings on POS Router Interfaces at the following URL:
http://www.cisco.com/en/US/tech/tk482/tk607/technologies_tech_note09186a0080094bb9.shtml
Command Purpose
Router(config-if)# crc [16 | 32] (As Required) Specifies the length of the cyclic
redundancy check (CRC), where:
• 16—Specifies a 16-bit length CRC. This is the
default.
• 32—Specifies a 32-bit length CRC.
The CRC size must be configured to be the same on
both ends of the POS link.
To Next Page
Loading...
Need help?
General
