[j-nsp] Strange Packet Loss Problem
Josef Buchsteiner
josefb at juniper.net
Sat Oct 21 09:26:31 EDT 2006
Christian,
if it is a data corruption on certain bit patterns then
you should see this problem also without rapid pings.
In order to find out where this happen I would
certainly perform a regular ping ( you may need more
packets ) and watch the icmp statistics to confirm that
it is data corruption in case you get icmp chksum
errors. "show system statistics icmp"
To find out if this is local or remote ( you could make
some statements with the icmp statistics already
however I prefer solid results)and you need to put this
sonet link into local loop and encapsulation cisco-hdlc
with no-keepalive. Then you perform the ping again with
bypass routing and interface knob to make sure the
traffic goes out and comes back in and you watch the
packet result and icmp statistics. This way you will
find out if this is local M40 or remote M40.
Once you know this it becomes kinda bit tricky. It
could be the FPC in question that is the trigger but
also other FPCs are contributing in the shared data
buffer which means you would need to turn off one by
one and see if the error stops. If you are left with
the OC-48 then I would suggest to replace this
particular FPC. To sanity check also other links of the
router if possible.
Check also the message log if you ever have seen
anytime ECC error reported. Just one of them is already
enough to give you some hints as you would not need to
do above isolation work
hope this helps
Josef
PS: yes I do have seen such symptoms in the past
and not only on one vendor.
Friday, October 20, 2006, 8:36:09 PM, you wrote:
CK>
CK>
CK> Hi All,
CK>
CK> I am experiencing a strange issue between 2 m40 core routers connect
CK> through an oc48 link
CK>
CK> I experience packet loss only when sending packets between 293 and 599
CK> bytes.
CK>
CK> I am also speaking to cold telecom about the issue to see if it's a
CK> problem with the sonet link, but as of now the link is not taking any
CK> errors or alarms.
CK>
CK> Anyone seen anything strange like this before?
CK>
CK> ckoch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 300
CK> PING 212.71.229.25 (212.71.229.25): 300 data bytes
CK>
CK> !.!!.!!.!!!!.!.!....!!.!!!!!..!..!!.!!!..!!.!!....!!.!...!!!...!.!.!..!.
CK> .!!...!....!..!.!.!!.!!.!!....!.!!!!!!..!..!.!!.!..!!.!!^C
CK> --- 212.71.229.25 ping statistics ---
CK> 129 packets transmitted, 66 packets received, 48% packet loss
CK> round-trip min/avg/max/stddev = 1.023/1.640/34.095/4.035 ms
CK>
CK> ckoch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 400
CK> PING 212.71.229.25 (212.71.229.25): 400 data bytes
CK> !!!!!!!!.!!!!!...!!^C
CK> --- 212.71.229.25 ping statistics ---
CK> 20 packets transmitted, 15 packets received, 25% packet loss
CK> round-trip min/avg/max/stddev = 1.074/1.111/1.348/0.071 ms
CK>
CK> ckoch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 500
CK> PING 212.71.229.25 (212.71.229.25): 500 data bytes
CK> !!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!^C
CK> --- 212.71.229.25 ping statistics ---
CK> 49 packets transmitted, 46 packets received, 6% packet loss
CK> round-trip min/avg/max/stddev = 1.141/1.202/2.514/0.210 ms
CK>
CK> ckoch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 600
CK> PING 212.71.229.25 (212.71.229.25): 600 data bytes
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!^C
CK> --- 212.71.229.25 ping statistics ---
CK> 955 packets transmitted, 954 packets received, 0% packet loss
CK> round-trip min/avg/max/stddev = 1.183/1.526/36.436/1.817 ms
CK>
CK> koch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 292
CK> PING 212.71.229.25 (212.71.229.25): 292 data bytes
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK>
CK> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
CK> !!!!!!!!^C!
CK> --- 212.71.229.25 ping statistics ---
CK> 916 packets transmitted, 916 packets received, 0% packet loss
CK> round-trip min/avg/max/stddev = 0.988/1.146/9.918/1.061 ms
CK>
CK> ckoch at core2.lhr3> ping rapid 212.71.229.25 count 10000 size 293
CK> PING 212.71.229.25 (212.71.229.25): 293 data bytes
CK> ..!!!.!^C
CK>
CK> Christian
CK> _______________________________________________
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CK>
CK>
CK>
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