System information

Troubleshooting LAN Switching Environments 22-457
LAN Switching: Poor Performance
Possible
Problem Solution
Full- or half-duplex
settings incorrect
Step 1 Check the switch port statistics. The following steps can be performed with the use of
the Cisco TrueView Catalyst 1600 Manager application.
The TrueView Catalyst 1600 Manager enables you to
• Find the status of a port
• Set the ring speed of a Token Ring port
• Select the port interface mode to be node or concentrator
• Select the port type to be classic or full duplex
• Assign a locally administered address to a Token Ring port or reset the hard-wired
address
• Configure source routing and spanning-tree parameters for a Token Ring port
• View source-routing counters for a Token Ring port
• Set the type of station that is connected to the Token Ring port, to enable the
Catalyst 1600 to block IPX and NetBIOS all-routes broadcast and single-route
broadcast frames originating on workstation-only rings and destined for other
workstation-only rings
Step 2 If there are FCS
1
and alignment errors on the port, check whether the port is
configured for full duplex.
Step 3 If the port is full duplex, check whether the other device is a repeater or half-duplex
device. If it is half duplex, configure the switch port for half duplex.
Step 4 If there are late collisions, check whether the port is configured for half duplex.
Step 5 If the port is half duplex, check whether the other device is full duplex. If it is,
configure the switch port for full duplex.
1 FCS = frame check sequence
Cabling distance
exceeded
Step 1 Check the switch port statistics. If you see excessive FCS, late-collision, or alignment
errors, the maximum cabling distance might be exceeded.
Step 2 Check the cable distance using a cable tester or TDR
2
. Verify that the VLAN segment
lengths attached to the switch meet Ethernet/IEEE 802.3 specifications.
Step 3 If the distance is out of specification, reduce the length of the cable run.
2 TDR = Time Domain Reflectometer
Bad adapter in
attached device
Check the switch port statistics. If excessive errors are found, run the adapter card diagnostic
utility to determine the problem. Refer to the user guide for your LAN switch for more
information. The following example of the show port counters command displays the type of
information that can be collected for each port on the switch:
show port counters 2
Bytes Transmitted: 19,339,380
Bytes Received: 455,390
Non-broadcast Frames Transmitted: 1,029
Non-broadcast Frames Received: 2,747
All Routes Explorer Frames Received: 0
All Routes Explorer Frames Transmitted: 4,289
Spanning Tree Explorer Frames Received: 259
Spanning Tree Explorer Frames Transmitted:28,065
Receiving Segment Mismatch Discards: 0
Duplicate Segment Mismatch Discards: 0
ARE Hop Count Exceeded Discards: 0