Smart Link Collaboration Mechanisms - HPE FlexNetwork HSR6800 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 mechanism
Because link switchover can outdate the MAC address forwarding entries and ARP/ND entries on all
devices, a forwarding entry update mechanism is needed to ensure proper transmission. The
following two update mechanisms are provided:
•
Uplink traffic-triggered MAC address learning—Update is triggered by uplink traffic. This
mechanism is applicable to environments with devices not supporting Smart Link, including
devices of 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 mechanism
As shown in
on GigabitEthernet 3/0/2 of Router C is the secondary link. Once the primary link fails,
GigabitEthernet 3/0/1 is automatically blocked and placed in standby state, and GigabitEthernet
3/0/2 takes over to forward traffic. When the primary link recovers, one of the following things
happen:
•
If the smart link group is not configured with role preemption, to keep traffic forwarding stable,
GigabitEthernet 3/0/1 does not immediately take over to forward traffic. Rather, it stays blocked
until the next link switchover.
•
If the smart link group is configured with role preemption, GigabitEthernet 3/0/1 takes over to
forward traffic as soon as its link recovers, and GigabitEthernet 3/0/2 is automatically blocked
and placed in standby state.
Load sharing mechanism
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 (each configured with
different protected VLANs), making sure that the state of the port is different in these smart link
groups. In this way, traffic of 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).

Smart Link collaboration mechanisms

When faults such as unidirectional links, misconnected fibers, or packet loss occur on intermediate
devices or network paths, Smart Link does not sense this on its own. Also, it cannot sense when
faults are cleared. To check the link status, Smart Link 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.
With the collaboration between Smart Link and the Continuity Check (CC) function of Connectivity
Fault Detection (CFD) configured, CFD notifies the ports of fault detection events on the basis of
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 the CC function of CFD, see "Configuring CFD."
Figure 28, the link on GigabitEthernet 3/0/1 of Router C is the primary link, and the link
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