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Switch A configuration sequence:
SwitchA(config)#uldp enable
SwitchA(config)#int erface et hernet 1/1
SwitchA (Config-If-Ethernet1/1)#uldp enable
SwitchA (Config-If-Ethernet1/1)#exit
SwitchA(config)#int erface et hernet1/2
SwitchA(Config-If-Et hernet1/2)#uldp enable
Switch B configuration sequenc e:
SwitchB(config)#uldp enable
SwitchB(config)#int erface et hernet1/3
SwitchB(Config-If-Et hernet1/3)#uldp enable
SwitchB(Config-If-Et hernet1/3)#exit
SwitchB(config)#int erface et hernet1/4
SwitchB(Config-If-Et hernet1/4)#uldp enable
As a result, port g1/1, g1/2 of SWITCH A are all shut down by ULDP, and there is notification information on
the CRT terminal of PC1.
%Oct 29 11:09:50 2007 A unidirectional link is detected! Port Ethernet1/1 need to be shutted down!
%Oct 29 11:09:50 2007 Unidirectional port Ethernet1/1 shut down!
%Oct 29 11:09:50 2007 A unidirectional link is detected! Port Ethernet1/2 need to be shutted down!
%Oct 29 11:09:50 2007 Unidirectional port Ethernet1/2 shutted down!
Port g1/3, and port g1/4 of SWITCH B are all shut down by ULDP, and there is notification information on the
CRT terminal of PC2.
%Oct 29 11:09:50 2007 A unidirectional link is detected! Port Ethernet1/3 need to be shutted down!
%Oct 29 11:09:50 2007 Unidirectional port Ethernet1/3 shutted down!
%Oct 29 11:09:50 2007 A unidirectional link is detected! Port Ethernet1/4 need to be shutted down!
%Oct 29 11:09:50 2007 Unidirectional port Ethernet1/4 shutted down!
10.4 ULDP Troubleshooting
Configuration Notice:
In order to ensure that ULDP can discover that the one of fiber ports has not connected or the ports are
incorrectly cross connected, the ports have to work in duplex mode and have the same rate.
If the automatic negotiation mechanism of the fiber ports with one port misconnected decides the
working mode and rate of the ports, ULDP won't take effect no matter enabled or not. In such situation,
the port is considered as "Down".
In order to mak e sure that neighbors can be correctly created and unidirectional links can be correctly
discovered, it is required that both end of the link should enable ULDP, using the same authentication
method and password. At present, no password is needed on both ends.
The hello interval of sending hello messages can be changed (it is10 seconds by default and ranges
from 5 to 100 s econds ) so that ULDP can respond faster to c onnection errors of links in different
network environments. But this interval should be less than 1/ 3 of the S TP convergence time. If t he
interval is too long, a STP loop will be generat ed before ULDP discovers and shuts down the
unidirectional connection port. If the interval is too short, the net work burden on the port will be
10-10
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Table of Contents
Troubleshooting
