3Com 3031 Command Reference Manual page 169

Fundamental CE1/PRI Interface Configuration Commands 169
frame-format Syntax
frame-format { crc4 | no-crc4 }
undo frame-format
View
CE1/PRI interface view
Parameter
crc4: Sets the frame format on the CE1 interface to CRC4.
no-crc4: Sets the frame format on the CE1 interface to no-CRC4.
Description
Using the frame-format command, you can set the frame format of CE1 interface.
Using the undo frame-format command, you can restore the default frame format
of the interface.
By default, the frame format of CE1 interface is no-crc4.
A CE1/PRI interface working in CE1 mode supports both crc4 and no-crc4 frame
formats. Among them, crc4 supports the 4-bit Cyclic Redundancy Check (CRC) on
physical frames whereas no-crc4 does not.
Example
Set the frame format of the interface E1 3/0/0 to crc4.
[3com-E1 3/0/0]frame-format crc4
loopback
Syntax
loopback { local | remote }
undo loopback
View
CE1/PRI interface view
Parameter
local: Enables the interface to perform local loopback.
remote: Enables the interface to perform remote loopback.
Description
Using the loopback command, you can enable a CE1/PRI interface to perform
loopback. Using the undo loopback command, you can disable the CE1/PRI
interface to perform loopback.