Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Bronze

Duplex Mismatch occurred only once at boot up

Hi everyone,

I encountered mysterious phenomenon on Cisco 7301, Catalyst 2960, Catalyst 3750 and Catalyst 6509 which were connected with Giga link and duplex setting were configured as "auto" on both Giga interfaces.

I have tested three cases.

The test I executed is that restarting Cisco 7301 by power off then on and confirming Cisco 7301 boot up successfully by looking at console message.

[Case 1]

Cisco 7301 Giga ---------- Giga Catalyst 2960

Both end Giga interfaces were configured as duplex "auto"

Cisco 7301 ran with IOS version 12.3(25)

Catalyst 2960 ran with IOS version 12.2(25)SEE4

[Case 2]

Cisco 7301 Giga ---------- Giga Catalyst 3750

Both end Giga interfaces were configured as duplex "auto"

Cisco 7301 ran with IOS version 12.3(25)

Catalyst 2960 ran with IOS version 12.2(25)SEE4

[Case 3]

Cisco 7301 Giga ---------- Giga Catalyst 6509

Both end Giga interfaces were configured as duplex "auto"

Cisco 7301 ran with IOS version 12.3(25)

Catalyst 2960 ran with IOS version 12.2(18)SXF9

The result of my testing were as follows,

[Case 1]

After restarting Cisco 7301, "%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on Gigabi" was generated and logged only once at boot up on both Cisco 7301 and Catalyst 2960.

However, this duplex mismatch occurred only once at boot up and after booting up successfully completed, duplex mismatch message was never generated and logged at all, and Giga link (both Giga interfaces) have been working normally.

[Case 2]

After restarting Cisco 7301, "%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on Gigabi" was generated and logged only once at boot up on both Cisco 7301 and Catalyst 3750.

However, this duplex mismatch occurred only once at boot up and after booting up successfully completed, duplex mismatch message was never generated and logged at all, and Giga link (both Giga interfaces) have been working normally.

[Case 3]

After restarting Cisco 7301, "%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on Gigabi" was not generated and logged at all.

I understand the result of Case 3 is normally and Case 1 and Case 2 might be the problem.

I do not understand why Case 1 and Case 2 occurred whereas Case 3.

Do you have any idea for this symptom ?

Can this symptom be occurred by autonegotiation functional issue on the rest of Catalyst 6509 ?

Your information would be appreciated.

Regards,

Shinichi

1 REPLY
Bronze

Re: Duplex Mismatch occurred only once at boot up

Cisco 7300 series and Cisco 6500 series support both duplex modes when running at 1000 Mbps,

"1000 Mbps and half duplexGigabit Ethernet only

"1000 Mbps and full duplexGigabit Ethernet only

whereas Cisco 2960 series and Cisco 3750 series support only one mode,

You can configure Gigabit Ethernet ports to full-duplex mode or to autonegotiate; you cannot configure half-duplex mode on Gigabit Ethernet ports.

The system message is displayed due to the difference in the capabilities of the devices.

278
Views
0
Helpful
1
Replies
CreatePlease to create content