03-16-2009 06:16 AM - edited 03-06-2019 04:36 AM
Hello
do any one know what does that mean in show interface fastether0/0 counter
unknown protcol drop , and why it increases
Thanks & BR
Moamen
03-16-2009 06:29 AM
Hello Moamen,
this error counter increments when frames that are correct at OSI layer 2 carry inside a protocol type that is not known or not running on the fas0/0 interface.
Example:
IS-IS packets are not ip packets we use it for routing, access layer switches count is-is hellos as unknown because they are not running IS-IS.
There are other possible reasons : ipv6 packets or layer 2 signalling packets like VTP or STP and others
if they increment regurarly over time like 1 one every 10 seconds or some every few seconds the reason is a not understood protocol.
if the number is not great you should be fine (no issues for your router)
Hope to help
Giuseppe
03-16-2009 06:53 AM
Hello,
Thanks fr your help, just do you have any document on Cisco support that , as our customer need such document becuse he think it is a problem .
Thanks & BR
Moamen
03-16-2009 07:47 AM
Hello Moamen,
unfortunately I couldn't find a clear explanation.
I tried to look at the command reference
http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_s4.html#wp1019043
However, if no real issue is seen in the network this is a so called cosmetic problem.
Hope to help
Giuseppe
03-16-2009 01:12 PM
Hi,
Can you provide us with the following output:
(1) show interface fastethernet 0/0 counter
(2) show interface fastethernet 0/0
(3) show version
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