ULPP Configuration
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62. ULPP Configuration
62.1
Introduction to ULPP
Each ULPP group has two uplink ports, they are master port and slave port. The port
may be a physical port or a port channel. The member ports of ULPP group have three
states: Forwarding, Standby, Down. Normally, only one port at the forwarding state, the
other port is blocked at the Standby state. When the master port has the link problem, the
master port becomes down state, and the slave port is siwthed to forwarding state.
Fig 62-1 the using scene of ULPP
The above figure uses the double-uplink network, this is the typical application scene
of ULPP. SwitchA goes up to SwitchD through SwitchB and SwitchC, port A1 and port A2
are the uplink ports. SwitchA configures ULPP, thereinto port A1 is set as the master port,
port A2 is set as the slave port. When port A1 at forwarding state has the problem, switch
the uplink at once, port A2 turns into forwarding state. After this, when recovering the
master port, if the preemption mode is not configured, port A2 keeps the Forwarding state,
port A1 turns into the Standby state.
After the preemption mode is enabled, so as to the master port preempts the slave
port when it recovered from the problem. For avoiding the frequent uplink switch caused
by the abnormity problem, the preemption delay mechanism is imported, and it needs to