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

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

unknown protcol drop

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

  • LAN Switching and Routing
4 REPLIES
Hall of Fame Super Silver

Re: unknown protcol drop

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

New Member

Re: unknown protcol drop

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

Hall of Fame Super Silver

Re: unknown protcol drop

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

Cisco Employee

Re: unknown protcol drop

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

131
Views
0
Helpful
4
Replies