Flex Links Configuration
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32.1.2.2 Link-Faulty Handling
When the primary link on Switch A fails, the master port GigabitEthernet 1/0/1 transits to
the standby state, while the slave port GigabitEthernet 1/0/2 transits to the forwarding state. A
link switchover occurs. After the link switchover, the MAC address forwarding entries kept
on the devices in the network may become incorrect, and need to be refreshed, so that traffic
can be rapidly switched to another link, thus avoiding traffic loss. Currently, one mechanisms
are available for refreshing MAC address forwarding entries: MMU message-notified
refreshing.
This mechanism is applicable when the upstream devices (such as Switch B, Switch C,
and Switch D in Figure 32-2) support Flex Link and are able to recognize MMU messages.
To enable rapid link switchover, you need to enable Switch A to send MMU messages, and
all upstream devices’ ports that are on the dual uplink network to receive and process MMU
messages.
After link switchover occurs on Switch A, MMU messages are sent along the new primary
link, that is, through GigabitEthernet 1/0/2. When an upstream device receives and handles a
MMU message, transmit MAC address carried in the MMU message to the receiving port.
After that, when Switch D receives a data packet destined for Host A, Host B, Host C,
switch D will broadcasts the packet at Layer 2; Switch C will search MAC address table after
receiving it, and forward it to Switch A from GE1/0/2; Switch A forward it to Host A
、
Host B,
Host C. In this way, data traffic can be forwarded correctly.
Tis mechanism will update MAC address without waiting for entry aged. Generally, the
whole link will be shifted in milliseconds without traffic lost.
32.1.2.3 Link-Recovery Working Modes
Flex Link supports three working modes: role preemption, non-role preemption and
bandwidth preemption. Under different modes, the port state changes are different:
If role preemption is configured, when the primary link recovers, the master port enters the
forwarding state and takes over the traffic, while the slave port enters the standby state. The
slave port transits from standby to forwarding only when the primary link fails.
If non-role preemption is configured, when the primary link recovers, the slave port
remains in the forwarding state, while the master port remains in the standby state, so as to
keep the traffic stable.
If bandwidth preemption is configured, when the primary link recovers, the slave port
remains in the forwarding state if it occupies more bandwidth, while the master port remains
in the standby state; The slave port transits from forwarding to standby only when master port
Summary of Contents for S6424-S2C2 series
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