Troubleshooting guide

11-24
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 11 Troubleshooting Layer 3 Network Connections
Troubleshooting Half- or Full-Duplex Negotiation
Use the show controllers fastEthernet card/subcard/port command to check the configuration.
The following example uses the Cisco IOS Release 12.0(5)W5(13) and earlier display:
Switch# show controller fastEthernet 1/0/0
IF Name: FastEthernet1/0/0
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(Information Deleted)
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MII registers:
Control Register (0x0): 0x1000
Status Register (0x1): 0x782D
PHY Identification Register 1 (0x2): 0x7810
PHY Identification Register 2 (0x3): 0x43
Auto Neg. Advertisement Reg (0x4): 0x1E1
Auto Neg. Partner Ability Reg (0x5): 0x1E1
Auto Neg. Expansion Register (0x6): 0x1
Mirror Register (0x10): 0x30
Interrupt Enable Register (0x11): 0x0
Interrupt Status Register (0x12): 0x4000
Configuration Register (0x13): 0x0
Chip Status Register (0x14): 0x38C8
Link Status Register [3-0]|[7-4]: 0x1|0x0
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(Information Deleted)
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Step 5 Check the Auto Neg. Advertisement Register (Reg 0x4). If it is set to 1, the following are the capabilities:
• Bit 8 - 100 BASE-TX Full Duplex
• Bit 7 - 100 BASE-TX
• Bit 6 - 10 BASE-T Full Duplex
• Bit 5 - 10 BASE-T
Step 6 Check the Auto Neg. Partner Ability Reg (Reg 0x5). If it is set to 1, the following are the status and
capabilities:
• Bit 14 - Link Partner has received the Link code word from the local
• Bit 13 - Remote Fault
• Bit 8 - 100 BASE-TX Full Duplex
• Bit 7 - 100 BASE-TX
• Bit 6 - 10 BASE-T Full Duplex
• Bit 5 - 10 BASE-T
Step 7 Check the Chip Status Register field. It should match the link status, duplex mode, and speed shown in
the show interface command in Step 2.