User's Manual

Configuration Guide of XGS-5240-Series
64-1
Chapter 64 ULSM Configuration
64.1 Introduction to ULSM
ULSM (Uplink State Monitor) is used to process the port state synchronization. Eac
h ULSM group is made up of the uplink port and the downlink port, both the uplink po
rt and the downlink port may be multiple. The port may be a physical port or a port c
hannel, 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 do
wn 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 li
nk problem of the upstream device and process correctly. As the picture illustrated, Swi
tchA configures ULPP, here the traffic is forwarded by port A1. If the link between Swit
chB and Switch D has the problem, SwitchA can not apperceive the problem of the up
stream 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 p
ort 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 stat
e of ULSM group are down. It causes Switch A on which ULPP is configured to proce
ss uplink switchover and avoid the data dropped.