Re: Strange packet loss symptom exhibited in JunOS 5.2R1.4

From: Chris (chris@cattle-today.com)
Date: Wed Jul 03 2002 - 11:17:17 EDT


Chris,
   I have seen this when the utilization on the Motorola processor on the FEB gets to around 40% or so. If you remember that is the processor that deals with all packets that have to be sent to the RE for processing(ie pings traceroutes and rand routing protocols). The reason you are seeing drops in your traceroute is, because the router knows that it is more important to take care of things like protocols before traceroutes. You should be able to check and see if this is the porblem by doing a show chassis feb
             Chris

lab@router4> show chassis feb
FEB status:
  Temperature 26 degrees C / 78 degrees F
  CPU utilization 1 percent <----------------This is it
  Interrupt utilization 0 percent
  Heap utilization 38 percent
  Buffer utilization 43 percent
  Total CPU DRAM 64 Mbytes
  Internet Processor II Version 1, Foundry IBM, Part number 9
  Start time: 2002-05-02 14:00:51 UTC
  Uptime: 62 days, 1 hour, 4 minutes, 12 seconds

--- Chris Roberts <croberts@bongle.co.uk> wrote:
>ello,
>
>
>I have an M5 and an M10 set up as follows:
>
> \ /
> o------o
> | |
>
>o is an m5 or an m10
>\/ are SONET links
>-| is gigabit ethernet
>
>i.e. a standard redundant pair. These two routers present a
>common VRRP address to the gigabit LAN segment.
>Now the strange thing I am seeing is that the M10 (5.2R1.4)
>seems to exhibit packet loss in traceroutes. The M5 (5.1R2.4)
>doesn't.
>
>From an mtr (apologies in advance about the long lines
>and router names removed to protect the not so innocent):
>
> 1. y.y.y.y ???????????????????.???
> 2. x.x.x.x .......................
> 3. x.x.x.x .......................
> 4. x.x.x.x .......................
>
>where y.y.y.y is the M10.
>I've messed around with this a bit, and it seems that this
>router has a generic problem responding to traceroutes that
>cross the gigabit interface. The wierd thing is that it's
>intermittent, and seems to be load related.
>
>Has anyone seem _anything_ like this before? In this case, the
>testing above was done from a directly connected segment, so
>I've tried the obvious like looking for the route to the
>source flapping, etc, and currently have a case open with
>the JTAC which doesn't seem to be progressing too rapidly.
>
>Anyone got any points on how to debug/diagnose this on a
>Juniper?
>
>Cheers,
>--
>|=========----- -------=======| CCNP - LAIT II
>| Chris Roberts (croberts@bongle.co.uk) | "If at first you don't succeed
>|=======------- -----=========| try a bigger hammer."

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