Chapter 32 Ulsm Configuration; Introduction To Ulsm - Edge-Core ES4624-SFP Basic Management Manual

Chapter 32 ULSM Configuration

32.1 Introduction to ULSM

ULSM (Uplink State Monitor) is used to process the port state synchronization. Each
ULSM group is made up of the uplink port and the downlink port, both the uplink port and
the downlink port may be multiple. The port may be a physical port or a port channel, but
it can not be a member port of a port channel, and each port only belongs to one ULSM
group.
The uplink port is the monitored port of ULSM group. When all uplink ports are down
or there is no uplink port in ULSM group, ULSM group state is down. ULSM group state is
up as long as one uplink port is up.
The downlink port is the controlled port, its state changes along with Up/Down of
ULSM group and is always the same with ULSM group state.
ULSM associates with ULPP to enable the downstream device to apperceive the link
problem of the upstream device and process correctly. As the picture illustrated, SwitchA
configures ULPP, here the traffic is forwarded by port A1. If the link between SwitchB and
Switch D has the problem, SwitchA can not apperceive the problem of the upstream link
and sequentially forward the traffic from port A1, cause traffic losing.
Configuring ULSM on SwitchB can solve the above problems. The steps are: set port
B5 as the uplink port of ULSM group, port B6 as the downlink port. When the link
between SwitchB and SwitchD has the problem, both the downlink port B6 and the state
of ULSM group are down. It causes Switch A on which ULPP is configured to process
uplink switchover and avoid the data dropped.
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