User's Manual

10-5
10.3 ULDP Function Typical Examples
Figure 10-3 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 ethernet1/0/2
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 ethernet1/0/4
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 notification information
on the CRT terminal of PC1.
g1/0/2
Switch B
g1/0/4
g1/0/3
g1/0/1
Switch A
PC1
PC2