Enabling Loopback Detection On An Ethernet Interface - HP 3600 v2 series Configuration Manual

Enabling loopback detection on an Ethernet interface

If a switch receives a packet that it sent, a loop has occurred to the switch. Loops might cause broadcast
storms, which degrade network performance. You can use this feature to detect whether a loop has
occurred.
Depending on whether the receiving interface is the same as the sending interface, loops fall into the
following type: single-port loopback and multi-port loopback.
Single-port loopback occurs when an interface receives a packet that it sent out and the receiving
•
interface is the same as the sending interface, as shown in
• Multi-port loopback occurs when a switch receives a packet that it sent out but the receiving
interface might not be the sending interface, as shown in
Figure 2 Single-port loopback
Figure 3 Multi-port loopback
You can enable loopback detection to detect loops on an interface and, if the interface supports the
loopback-detection action command, configure the protective action to take on the receiving interface
when a loop is detected, for example, to shut down the interface. Depending on whether a protective
action is configured, the switch takes the actions in
Table 1 Actions to take upon detection of a loop condition
Port type
Access port
Actions
No protective action is configured
•
Place the receiving interface in controlled mode.
The interface does not receive or send packets.
•
Generate traps.
•
Delete all MAC address entries of the interface.
Figure
Figure
Table 1 to alleviate the impact of the loop condition.
A protective action is configured
•
•
•
11
2.
3.
Perform the configured protective
action.
Generate traps and log messages.
Delete all MAC address entries of the
interface.