R2511-HP MSR Router Series Interface Configuration Guide(V5)

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when a loop is detected, for example, to shut down the interface. When no protective action is
configured, the device takes the actions in Table 1 t
o alleviate the impact of the loop condition.
Table 1 Actions to take upon detection of a loop condition
Port t
yp
e Actions when no
p
rotective action is confi
g
ured
Access port
• Place the receiving interface in controlled mode. The interface discards all
incoming packets, but still forwards outgoing packets.
• Generate traps.
• Delete all MAC address entries of the interface.
Hybrid or trunk port
• Generate traps.
• If loopback detection control is enabled, place the receiving interface in controlled
mode. The interface discards all incoming packets, but still forwards outgoing
packets.
• Delete all MAC address entries of the interface.
Configuration restrictions and guidelines
• To use loopback detection on an Ethernet interface, you must enable the function both globally and
on the interface.
• To disable loopback detection on all interfaces, run the undo loopback-detection enable command
in system view.
• To enable a hybrid or trunk port to take the administratively specified protective action, you must use
the loopback-detection control enable command on the port.
Configuration procedure
To configure loopback detection:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enable global loopback
detection.
loopback-detection enable
By default, global loopback
detection is disabled.
3. Set the loopback detection
interval.
loopback-detection interval-time
time
Optional.
The default setting is 30 seconds.
4. Enter Ethernet interface view.
interface interface-type
interface-number
N/A
5. Enable loopback detection on
the interface.
loopback-detection enable
By default, loopback detection is
disabled.
6. Enable loopback detection
control on a trunk port or a
hybrid port.
loopback-detection control enable
Optional.
By default, loopback detection
control is disabled.