User's Manual

Table Of Contents
367
Users Manual of CS-6306R
39.1.3.3 Configuring a Port to Conduct Loopback Detection in Specified VLAN
If you set loopback detection in a specified VLAN, a port shall transmit multiple detection packets with
specified VLAN tag regularly and the port can transmit up to 10 detection packets with specified VLAN tag.
One point to be noted is that the port must exist in the specified VLAN, or the configuration takes no effect. If
loopback detection happens in VLAN2 to VLAN8, ports are configured to be in trunk mode, and trunk
vlan-allowed is vlans 5-8, the packets with tags 2-4 transmitted by the switch cannot pass through this port
and the configuration hence takes no effect.
Command Purpose
[no] loopback-detection vlan-control
vlanlist
Configures a port to conduct loopback
detection in specified VLAN.
39.1.3.4 Configuring the Loopback Detection Interval of Port (Packet transmission
interval, controlled port recovery time)
Command Purpose
[no] loopback-detection hello-time time
Configures the transmission interval of port
loopback detection packets.
Because a network is always changeable, loopback detection is a continuous process. The port will transmit
loopback detection packets in a regular time. This regular time is called as the transmission interval of
loopback detection packets. The default transmission interval of the system is 3 seconds.
Command Purpose
[no] loopback-detection recovery-time
time
Configures the transmission interval of port
loopback detection packets.
This command above is used to set the automatic recovery time of a port when loopback disappears. In
default settings, if a port has not received the already transmitted loopback detection packet within 10
seconds, it is regarded that loopback vanishes. It is recommended to set the recovery time to be triple of the
packet transmission time; if the transmission time is set to be a very small value, you'd better set the recovery
time to be at least 10 seconds longer than the transmission time.
39.1.3.5 Configuring Port Control
Command Purpose
[no] loopback-detection control
{block|learning|shutdown}
Configures port control.
When a port detects that loopback exists in its network, you can set port control to manage this port. The
control state of a port can be block, nolearn, shutdown or trap. When any control state is set and loopback
exists on a port, the trap alarm message will be transmitted. It is not configured by default.
When loopback detection is enabled globally, a loopback detection packet is transmitted from a port, on which
loopback detection is enabled, and received again by this port, the port may get the following four control
actions:
Block: When loopback is found, this port is then isolated from other ports. Hence the packets entering this port
cannot be forwarded to other ports. The port is then in protocol down state and its MAC address table list