Loopback; Mtu (On Serial Interfaces) - H3C MSR 20-20 Command Reference Manual

loopback

Syntax
View
Parameter
Description
Example

mtu (on serial interfaces)

Syntax
View
Parameter
Description
loopback
undo loopback
Serial interface view, AUX interface view, AM interface view
None
Use the command to enable internal loopback on the serial interface.
loopback
Use the undo loopback
By default, loopback is disabled.
Loopback is intended for test use. Disable it otherwise.
# Enable internal loopback on interface Serial 2/0.
<Sysname> system-view
[Sysname] interface serial 2/0
[Sysname-Serial1/0] loopback
mtu size
undo mtu
Serial interface view, AUX interface view, AM interface view, USB interface view
size: Maximum transmission unit (MTU) to be set for a serial interface, in the range
128 to 1,500 (in bytes).
Use the command to set the MTU for a serial interface.
mtu
Use the command to restore the default.
undo mtu
By default, the MTU of a serial interface is 1,500 bytes.
Due to the length of Qos queue, a packet may be discarded if the MTU is relatively
small and the packet is segmented into too many fragments. You can increase the
Qos queue length to avoid this situation. To do so, use the qos fifo queue-length
command in interface view. For details, refer to the "FIFO Queuing Configuration
Commands" on page 1809.
The MTU setting can affect IP packets assembly and fragmentation on the
interface.
command to restore the default.
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