Enabling Loopback Tests - Cisco 10000 Series Configuration Manual

SDCC Interface Configuration Commands

Enabling Loopback Tests

You can configure an SDCC interface for an internal loopback test by using the loopback command.
With an internal loopback, packets that are received by the line card from the route processor are looped
back to the route processor without being sent to the line.
loopback
[no] loopback
Use the no form of the command to stop the loopback test.
The default is none.
In the following example, the loopback is set to line:
Router(config-if)# loopback
Configuring CRC Size
You can configure the CRC size for HDLC encapsulation on an SDCC interface to 16- and 32-bit CRCs
using the crc command.
crc {16 | 32}
Where:
16 sets the CRC to 16 bits.
32 sets the CRC to 32 bits.
The default is 32.
In the following example, the CRC size is set to 16:
Router(config-if)# crc 16
Configuring MTU Size
You can configure the Maximum Transmission Unit (MTU) size for up to 1500 bytes, using the mtu
command.
The MTU size does not include the 4 bytes for the HDLC header, or the 2 or 4 bytes of the CRC.
Note
mtu
Where mtu bytes is the MTU size from zero to 1500.
The default is 1500.
In the following example, the MTU size is set to 1000:
Router(config-if)# mtu 1000
Cisco 10000 Series Router Line Card Configuaration Guide
14-6
mtu bytes
Chapter 14 1-Port OC-48/STM-16 Packet over SONET Line Card Configuration
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