Switch/router duplex setup question

swtlrichswtlrich Member Posts: 8 ■□□□□□□□□□
Here's what I have:

Switch A is Catalyst 1924
Switch B is Catalyst 1924
Switch C is Intel 410T Standalone (10/100 on all ports)
Router is Cisco 2511

Switch A and B are both connected via their 100 Mb TX ports to Switch C. 2511 router is connected to another port on Switch C also. The link ports involving the 3 switches connectivity to each other are configured Full Duplex, no flow control. The link port on Switch C that the router is connected to is set Autonegotiate (the router is only 10Mb capable).

As soon as I finished setting that up, I began to receive CDP duplex mismatch messages with each cdp update (one per minute). The messages references the ID for Switch A (one of the 1924s) everytime, but makes no mention of the other 2 switches. When I change port config on the switches links to each other to Half Duplex, the mismatch messages on the router ceases. I guess I don't understand why full duplex setup between the switches only is triggering the cdp error on the router? I know I can also just disable cdp, but I'd rather have an answer so I can optimize my network.

Any suggestions? Thanks, all.
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