Monitoring Lag Links; Setting The Failover Limit - Lenovo RackSwitch G8264 Application Manual

Monitoring LAG Links

Setting the Failover Limit

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G8264 Application Guide for ENOS 8.4
Layer 2 Failover can be enabled on any LAG in the G8264, including LACP LAGs.
LAGs can be added to failover trigger groups. Then, if some specified number of
monitor links fail, the switch disables all the control ports in the switch. When the
control ports are disabled, it causes the NIC team on the affected servers to failover
from the primary to the backup NIC. This process is called a failover event.
When the appropriate number of links in a monitor group return to service, the
switch enables the control ports. This causes the NIC team on the affected servers
to fail back to the primary switch (unless Auto‐Fallback is disabled on the NIC
team). The backup switch processes traffic until the primary switch's control links
come up, which can take up to five seconds.
Figure 59 is a simple example of Layer 2 Failover. One G8264 is the primary, and
the other is used as a backup. In this example, all ports on the primary switch
belong to a single LAG, with Layer 2 Failover enabled, and Failover Limit set to 2.
If two or fewer links in trigger 1 remain active, the switch temporarily disables all
control ports. This action causes a failover event on Server 1 and Server 2.
Figure 59. Basic Layer 2 Failover
Enterprise
Routing Switches
Internet
The failover limit lets you specify the minimum number of operational links
required within each trigger before the trigger initiates a failover event. For
example, if the limit is two, a failover event occurs when the number of operational
links in the trigger is two or fewer. When you set the limit to zero, the switch
triggers a failover event only when no links in the trigger are operational.
Primary
Switch
Trigger 1
Backup
Switch
Trigger 1
Server 1
NIC 1
NIC 2
Server 2
NIC 1
NIC 2