FastIron GS Compact Layer 2 Switch Hardware Installation Guide
4 - 8 © 2007 Foundry Networks, Inc. September 2007

Tracing a Route

To determine the path through which a Foundry device can reach another device, enter a command such as the
following at any level of the CLI on the Foundry device:
FastIron>traceroute 192.33.4.7
Syntax: traceroute <host-ip-addr> [maxttl <value>] [minttl <value>] [numeric] [timeout <value>]
[source-ip <ip addr>]
The CLI displays trace route information for each hop as soon as the information is received. Traceroute requests
display all responses to a given TTL. In addition, if there are multiple equal-cost routes to the destination, the
Foundry device displays up to three responses by default.
Troubleshooting Network Connections
• For the indicated port, verify that both ends of the cabling (at the Foundry device and the connected device)
are snug.
• Verify that the Foundry device and the connected device are both powered on and operating correctly.
• Verify that you have used the correct cable type for the connection:
• For twisted-pair connections to an end node, use straight-through cabling.
• For fiber-optic connections, verify that the transmit port on the device is connected to the receive port on
the connected device, and that the receive port on the device is connected to the transmit port on the
connected device.
• Verify that the port has not been disabled through a configuration change. You can use the CLI. If you have
configured an IP address on the device, you also can use the Web management interface or IronView
Network Manager.
• For copper ports, you can test the cable using Virtual Cable Testing. See “Using Virtual Cable Testing to
Diagnose a Cable” .
• If the other procedures don’t resolve the problem, try using a different port or a different cable.

Using Virtual Cable Testing to Diagnose a Cable

FGS devices support Virtual Cable Test (VCT) technology. VCT technology enables you to diagnose a conductor
(wire or cable) by sending a pulsed signal into the conductor, then examining the reflection of that pulse. This
method of cable analysis is referred to as Time Domain Reflectometry (TDR). By examining the reflection, the
Foundry device can detect and report cable statistics such as local and remote link pair, cable length, and link
status.

Configuration Notes

• This feature is supported on copper ports only. It is not supported on fiber ports.
• The port to which the cable is connected must be enabled when you issue the command to diagnose the
cable. If the port is disabled, the command is rejected.
• If the port is operating at 100 Mbps half-duplex, the TDR test on one pair will fail.
• If the remote pair is set to forced 100 Mbps, any change in MDI/MDIX may cause the device to interpret the
Multilevel Threshold-3 (MLT-3) as a reflected pulse, in which case, the device will report a faulty condition. In
this case, Foundry recommends that you run the TDR test a few times for accurate results.

Command Syntax

To diagnose a cable using TDR, enter a command such as the following at the Privileged EXEC level of the CLI:
FastIron#phy cable-diag tdr 1
The above command diagnoses the cable attached to port 1.
Syntax: phy cable-diag tdr <port-num>