Smart Link Collaboration Mechanisms - HP 5900 Series Configuration Manual

When a port switches to the forwarding state, the system outputs log information to notify the user of the
port state change.
Topology change
Link switchover can outdate the MAC address forwarding entries and ARP/ND entries on all devices, so
a forwarding entry update mechanism is required to ensure proper transmission. The following update
mechanisms are provided:
Uplink traffic-triggered MAC address learning—Update is triggered by uplink traffic. This
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mechanism is applicable to environments with devices that do not support Smart Link, including
devices from other vendors.
• Flush update—A Smart Link-enabled device updates its information by transmitting flush messages
over the backup link to its upstream devices. This mechanism requires the upstream devices to be
capable of recognizing Smart Link flush messages to update their MAC address forwarding entries
and ARP/ND entries.
Role preemption
As shown in
C is the secondary link. Once the primary link fails, Port 1 is automatically blocked and placed in
standby state, and Port 2 takes over to forward traffic. When the primary link recovers, one of the
following actions occurs:
• To keep traffic forwarding stable if the smart link group is not configured with role preemption, Port
1 does not immediately take over to forward traffic. It stays blocked until the next link switchover.
If the smart link group is configured with role preemption, Port 1 takes over to forward traffic as soon
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as its link recovers, and Port 2 is automatically blocked and placed in standby state.
Load sharing
A ring network might carry traffic of multiple VLANs. Smart Link can forward traffic from different VLANs
in different smart link groups for load sharing.
To implement load sharing, you can assign a port to multiple smart link groups. Configure each group
with a different protected VLAN. Make sure the state of the port is different in these smart link groups, so
traffic from different VLANs can be forwarded along different paths.
You can configure protected VLANs for a smart link group by referencing Multiple Spanning Tree
Instances (MSTIs). For more information about MSTIs, see Layer 2—LAN Switching Configuration Guide.

Smart Link collaboration mechanisms

Collaboration between Smart Link and Monitor Link
Smart Link cannot detect when faults occur on the uplink of the upstream devices or when faults are
cleared. You can configure the Monitor Link function to monitor the status of the uplink ports of the
upstream devices. Monitor Link adapts the up/down state of downlink ports to uplink ports, and triggers
Smart Link to perform link switchover on the downstream device. For more information about Monitor Link,
see "Configuring Monitor
Collaboration between Smart Link and Track
Smart Link cannot detect when faults such as unidirectional links, misconnected fibers, or packet loss
occur on intermediate devices or network paths or when faults are cleared. To check the link status, smart
link group member ports must use link detection protocols. When a fault is detected or cleared, the link
detection protocols inform Smart Link to switch over the links.
Figure 12, the link on Port 1 of Device C is the primary link, and the link on Port 2 of Device
Link."
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