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ULDP Function Configuration
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8.3
ULDP Function Typical Examples
Fig 8-2 Fiber Cross Connection
In the network topology in Graph, port g1/0/1 and port g1/0/2 of SWITCH A as well as
port g1/0/3 and port g1/0/4 of SWITCH B are all fiber ports. And the connection is cross
connection. The physical layer is connected and works normally, but the data link layer is
abnormal. ULDP can discover and disable this kind of error state of link. The final result is
that port g1/0/1, g1/0/2 of SWITCH A and port g1/0/3, g1/0/4 of SWITCH B are all shut
down by ULDP. Only when the connection is correct, can the ports work normally (won‘t
be shut down).
Switch A configuration sequence:
SwitchA(config)#uldp enable
SwitchA(config)#interface ethernet 1/0/1
SwitchA(Config-If-Ethernet1/0/1)#uldp enable
SwitchA(Config-If-Ethernet1/0/1)#exit
SwitchA(config)#interface ethernet 1/0/2
SwitchA(Config-If-Ethernet1/0/2)#uldp enable
Switch B configuration sequence:
SwitchB(config)#uldp enable
SwitchB(config)#interface ethernet1/0/3
SwitchB(Config-If-Ethernet1/0/3)#uldp enable
SwitchB(Config-If-Ethernet1/0/3)#exit
SwitchB(config)#interface ethernet 1/0/4
SwitchB(Config-If-Ethernet1/0/4)#uldp enable
As a result, port g1/0/1, g1/0/2 of SWITCH A are all shut down by ULDP, and there is
g1/0/2
Switch B
g1/0/4
g1/0/3
g1/0/1
Switch A
PC1
PC2