ECS4620 series, ECS4510 series, ECS4120 series, ECS4100 series,
ECS3500 series, ECS4110 series, ECS2110 series, ECS2100 series
On Edgecore switches, non-STP loopback detection is another function to prevent the loop issue and it can detect the loop for each VLAN.
1. Configuration example:
If a user enables the loopback-detection and configures the VLAN 1~10 on port 1 as follows.
Console(config)#interface ethernet 1/1
Console(config-if)#switchport allowed vlan add 1-10 tagged
Then port 1 will send 10 LBD packets to detect the loop for each VLAN.
*Notice: Since loopback-detection will detect the loop for each VLAN, the, "ingress-filtering" function will be enabled automatically when you enable loopback-detection on an interface.
If switch receives its own LBD packet then it will know that a loop occurred on this port and VLAN. The user could know that the port was shutdown by LBD from "LBD status", "Interface status" and "Log".
2. The user can manually configure the following loopback-detection parameters:
The user can specify the interval time for transmitting LBD packets. By default, it is 10s.
Console(config)#loopback-detection transmit-interval ?
<1-32767> Specifies transmission interval in seconds
The user can specify “recover time” when the port is shutdown by LBD, by default it is 60s.
Console(config)#loopback-detection recover-time ?
0 Disables auto recovery
<60-1000000> Specifies recovery time in seconds
After the time is up then the port’s link will be recovered (if the network is no longer looped), and the switch will have a log.
 10:14:03 2018-01-25
"LBD recovers port 1."
level : 6, module : 5, function : 1, and event no. : 1
There are three actions for loopback-detection, by default it is “shutdown”.
Console(config)#loopback-detection action ?
block Specifies action to block looped VLANs from the interface
none Specifies action to do nothing
shutdown Specifies action to shutdown the interface
The status on each actions when switch detect the loop:
User can specify the switch to send a SNMP trap when it detect a loop.
Console(config)#loopback-detection trap ?
both Specifies to send both detection and recovery traps
detect Specifies to send trap when loop is detected
none Specifies to not send any trap
recover Specifies to send trap when recovery is done
3. STP LBD and non-STP LBD default setting on each models: