To rule out
hardware issues, verify the following:
?– The port status for both ports involved in the link: Ensure that neither is shut down.
The administrator may have manually shut down one or both ports, or the switch
software may have shut down one of the ports because of a con?¬?guration error. If one
side is shut down and the other is not, the status on the enabled side will be
???notconnected??? (because it does not sense a neighbor on the other side of the wire).
The status on the shutdown side will say something like ???disable??? or ???errDisable???
(depending on what actually shuts down the port). The link will not be active unless
both ports are enabled.
?– The type of cable used for the connection: You should use at least Category 5 cable
for 100 Mbps connections, and Category 5e for 1 Gbps or faster. You use a straightthrough
RJ-45 cable for end stations, routers, or servers to connect to a switch or hub.
You use an Ethernet crossover cable for switch-to-switch connections or hub-to-switch
connections. The maximum distance for Ethernet, FastEthernet, or Gigabit Ethernet
copper wires is 100 meters.
Troubleshoot
Physical Layer/
Port Connectivity
Issues
Troubleshoot
VLAN/Trunking
Issues
Troubleshoot
VTP
Issues
Troubleshoot
Spanning-Tree
Issues
Correct
cable type,
category,
length?
Is port VLAN
membership
correct?
Are
local and peer
ports up and not
admin down or
err-disabled?
Duplex
mismatch?
Troubleshooting Switched Networks 79
?– A software process disables a port: A solid orange light on the port indicates that the
switch software has shut down the port, either by way of the user interface or by
internal processes such as spanning tree BPDU guard; Root Guard, which prevents a
port from becoming the root port; or port security violations.
Pages:
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141