Routing

I found this link online but i still not sure if this is big issue or not?

 

 

http://www.gossamer-threads.com/lists/nsp/juniper/4868

 

Hello,

 

We have Juniper routers connected to Foundry switch network. Juniper interface reports L3 incompletes but that doesn't increases constantly. It increases randomly. Does anyone else here observed this issue?  

#incomplete
#L3

From JTAC

 
  Policed Discards

Frames that the incoming packet match code discarded because they were not recognized or of interest. Usually, this field reports protocols that the JUNOS software does not handle, such as CDP.

L3 incompletes
This counter is incremented when the incoming packet fails Layer 3 (usually IPv4) sanity checks of the header. For example, a frame with less than 20 bytes of available IP header would be discarded and this counter would be incremented.

L2 channel errors
This counter increments when the software could not find a valid logical interface (that is, something like t3-1/2/3.0) for an incoming frame.

o    L2 mismatch timeouts
Count of malformed or short packets that cause the incoming packet handler to discard the frame as unreadable.


L3 incompletes are usually not a concern unless you have counters that are showing them in the billions or even trillions.  If you have LDP configured on the other side, this could very well cause an L3 incomplete to be logged.  LDP sends hello messages every few seconds and because the interface isn’t configured for LDP, the hello message received would not pass the sanity check.

 

 Note that disabling LDP on the remote end interface did not resolve the issue.

I am having an issue with policed discards.  They are showing up on all 12 interfaces on an M10i. They even show up on interfaces that are disabled. I understand that policed discards are just packets that may be a protocol that Juniper doesn't recognize, but how do I see those packets?  How can I see where they are coming from? 

 

I supsect this is a 12x FE PIC.  The reason the counters increment for all interfaces, is because they all share the same input stream on the I/O manager ASIC, where the drops happen.  It is most often the result of a protocol that the microcode does not recoginize.  Like others have said, these are likely harmless.  There is no easy way to determine on which port(s) those frames arrived, as they are dropped before route lookup.

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@MitchIT wrote:

I am having an issue with policed discards.  They are showing up on all 12 interfaces on an M10i. They even show up on interfaces that are disabled. I understand that policed discards are just packets that may be a protocol that Juniper doesn't recognize, but how do I see those packets?  How can I see where they are coming from? 

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