SNR S2989G-48TX-POE Руководство по настройке онлайн [420/553] 747269

Превью страниц Страница 420 / 553

S2989G-24TX Operation Manual

Chapter 7 Reliability Configuration

7-21

Figure 7-8 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

wait for some times before the master port preempt the slave port. For keeping the

continuance of the flows, the master port does not process to preempt by default, but

turns into the Standby state.

When configuring ULPP, it needs to specify the VLAN which is protected by this

ULPP group through the method of MSTP instances, and ULPP does not provide the

protection to other VLANs.

When the uplink switch is happennig, the primary forwarding entries of the device will

not be applied to new topology in the network. In the figure, SwitchA configures ULPP, the

portA1 as the master port at forwarding state, here the MAC address of PC is learned by

Switch D from portD3. After this, portA1 has the problem, the traffic is switched to portA2

to be forwarded. If there is the data sent to PC by SwitchD, still the data will be forwarded

from portD3, and will be losed. Therefore, when switching the uplink, the device of