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Unknown protocol drops in Cisco 3945 Router interface

SrikantRajeev
SrikantRajeev used Ask the Experts™
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I am geting the error "162 unknown protocol drops" in my  Cisco 3945 router on int gigabit connected to Cisco 6509
The errors are increasing.
What could be the reasons for this error
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Commented:
It's hard to tell if that an input or an output error. If it's input,
is it possible you're receiving protocols you don't have configured -
IPX, Appletalk, IPv6, some other ethercode? Something to do with the
PPPOE maybe?

Put a sniffer on the line, it will show you everything passing through the nic.  Wiresharp or ethereal are the best sniffers.

Author

Commented:
Is this error critical
Is there any way i can find why this error is happening apart from using sniffer
I would suggest using Wireshark as well, it would be the best way to determine what's going on.

Author

Commented:
I am sitting remotely & checking it
no feasibily of installing wireshard.
Is this error critical
any debug option can help
I doubt it's critical, but maybe CDP is disabled on one router but not the other? That would certainly cause unknown protocol drops.
Look for no cdp enable in your running-config

Did you run through the one-step lockdown or autosecure?

Author

Commented:
what is one-step lockdown or autosecure
I am not aware of this

Author

Commented:
I tried no cdp enable but the error increases again
Was no cdp enable already in the config? If so, try enabling it.
You do that by running cdp enable

Author

Commented:
i did it
its same result
errors are increasing
Top Expert 2010
Commented:
what is connected to this swtichport?
What is the model of the linecard?

Billy