37-11
Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 37 Troubleshooting
Diagnosing Connectivity Problems
After inserting a Cisco-approved GBIC module, use the errdisable recovery cause gbic-invalid global
configuration command to verify the port status, and enter a time interval for recovering from the
error-disabled state. After the elapsed interval, the switch brings the interface out of the error-disabled
state and retries the operation. For more information about the errdisable recovery command, refer to
the command reference for this release.
Diagnosing Connectivity Problems
This section describes how to troubleshoot connectivity problems:
• Using Ping, page 37-11
• Using IP Traceroute, page 37-12
• Using Layer 2 Traceroute, page 37-14
Using Ping
This section consists of this information:
• Understanding Ping, page 37-11
• Executing Ping, page 37-11
Understanding Ping
The switch supports IP ping, which you can use to test connectivity to remote hosts. Ping sends an echo
request packet to an address and waits for a reply. Ping returns one of these responses:
• Normal response—The normal response (hostname is alive) occurs in 1 to 10 seconds, depending
on network traffic.
• Destination does not respond—If the host does not respond, a no-answer message is returned.
• Unknown host—If the host does not exist, an unknown host message is returned.
• Destination unreachable—If the default gateway cannot reach the specified network, a
destination-unreachable message is returned.
• Network or host unreachable—If there is no entry in the route table for the host or network, a
network or host unreachable message is returned.
Executing Ping
If you attempt to ping a host in a different IP subnetwork, you must define a static route to the network
or have IP routing configured to route between those subnets. For more information, see Chapter 31,
“Configuring IP Unicast Routing.”
IP routing is disabled by default on all switches. If you need to enable or configure IP routing, see
Chapter 31, “Configuring IP Unicast Routing.”
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