H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – Port Correlation Configuration
H3C S7500E Series Ethernet Switches Chapter 1 Port Correlation Configuration
1-8
1.1.9 Enabling Loopback Detection on an Ethernet Port
Loop occurs when a port receives the packets that it sent out. Loops may cause
broadcast storm. The purpose of loopback detection is to detect loops on a port..
With loopback detection enabled on an Ethernet port, the device checks the port for
external loopback periodically. Once a loopback is detected on the port, the system
does the following:
z If loops are detected on a port that is of access type, the port will be shutdown.
Meanwhile, trap messages will be sent to the terminal, and the corresponding
MAC address forwarding entries will be removed.
z If loops are detected on a port that is of trunk or hybrid type, trap messages are
sent to the terminal. If the loopback detection control function is also enabled on
the port, the port will be blocked, trap messages will be sent to the terminal, and
the corresponding MAC address forwarding entries will be removed.
Follow these steps to configure loopback detection:
To do... Use the command... Remarks
Enter system view
system-view
—
Enable global loopback
detection
loopback-detection
enable
Required
Disabled by default
Configure the interval for
port loopback detection
loopback-detection
interval-time time
Optional
30 seconds by default
Enter Ethernet port view
interface interface-type
interface-number
—
Enable loopback
detection on a port
loopback-detection
enable
Required
Disabled by default
Enable loopback
detection control on a
Trunk port or a Hybrid port
loopback-detection
control enable
Optional
Disabled by default
Enable loopback
detection in all the VLANs
containing the port
loopback-detection
per-vlan enable
Optional
Enabled only in the
default VLAN(s) with
Trunk port or Hybrid ports