Smart Link Collaboration Mechanisms - HPE FlexFabric 5700 Series Configuration Manual

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
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 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
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.
Smart Link collaborates with link detection protocols through track entries. It supports only the
Continuity Check (CC) function of Connectivity Fault Detection (CFD) to implement link detection.
CFD notifies the smart link group member ports of fault detection events by using detection VLANs
and detection ports. A port responds to a continuity check event only when the control VLAN of the
smart link group to which it belongs matches the detection VLAN. For more information about track
entries and the CC function of CFD, see
Figure 23, the link on Port 1 of Device C is the primary link. The link on Port 2 of Device
"Configuring Monitor Link."
"Configuring Track" and
91
"Configuring CFD."