[j-nsp] strange packet loss without impact

Derick Winkworth dwinkworth at att.net
Mon Jul 4 21:58:39 EDT 2011


1.  Have you thought of running your ping tests *thru* the box rather than *at* 
it?
2.  I see you have pretty symmetrical in/out here, could you be experiencing 
something like a DDOS (router pushing out too many ICMPs)?
3.  Packet capture at all?
4.  19k pps... is this high/normal/low for this interface?  Do you have services 
enabled on it?  J-Series is software router...



________________________________
From: Matthias Brumm <matthias at brumm.net>
To: Christian <cdebalorre at neotelecoms.com>
Cc: juniper-nsp at puck.nether.net
Sent: Mon, July 4, 2011 10:25:38 AM
Subject: Re: [j-nsp] strange packet loss without impact

no, that is not the problem. I have looked into the Juniper definition and
we have one discard routing entry, which should be responsible for this
entry.

the complete output:

show pfe statistics traffic
Packet Forwarding Engine traffic statistics:
    Input  packets:         586522987655                19925 pps
    Output packets:         585165208482                19866 pps
Packet Forwarding Engine local traffic statistics:
    Local packets input                 :           1228194454
    Local packets output                :            713668140
    Software input control plane drops  :                    0
    Software input high drops           :                    0
    Software input medium drops         :                13059
    Software input low drops            :                    0
    Software output drops               :                    0
    Hardware input drops                :                    0
Packet Forwarding Engine local protocol statistics:
    HDLC keepalives            :                    0
    ATM OAM                    :                    0
    Frame Relay LMI            :                    0
    PPP LCP/NCP                :                    0
    OSPF hello                 :                    0
    OSPF3 hello                :                    0
    RSVP hello                 :                    0
    LDP hello                  :                    0
    BFD                        :                    0
    IS-IS IIH                  :                    0
    LACP                       :                    0
    ARP                        :            513852055
    ETHER OAM                  :                    0
    Unknown                    :                    0
Packet Forwarding Engine hardware discard statistics:
    Timeout                    :                    0
    Truncated key              :                    0
    Bits to test               :                    0
    Data error                 :                    0
    Stack underflow            :                    0
    Stack overflow             :                    0
    Normal discard             :            557514914
    Extended discard           :                    0
    Invalid interface          :                    0
    Info cell drops            :                    0
    Fabric drops               :                    0
Packet Forwarding Engine Input IPv4 Header Checksum Error and Output MTU
Error :
    Input Checksum             :               132684
    Output MTU                 :                   34

2011/7/4 Matthias Brumm <matthias at brumm.net>

> Hello!
>
> show pfe statistics traffic is the first command, showing some errors:
>
> Packet Forwarding Engine hardware discard statistics:
>     Timeout                    :                    0
>     Truncated key              :                    0
>     Bits to test               :                    0
>     Data error                 :                    0
>     Stack underflow            :                    0
>     Stack overflow             :                    0
>     Normal discard             :            557491798
>     Extended discard           :                    0
>     Invalid interface          :                    0
>     Info cell drops            :                    0
>     Fabric drops               :                    0
>
> Is "Normal discard" an error or something "Normal", as the name would say.
>
>
> Matthias
>
> 2011/7/4 Christian <cdebalorre at neotelecoms.com>
>
>> **
>>
>> If in doubt run show system processes summary to check for busy process
>> during your peak time.
>> Also you can have some interesting stats with a show pfe statistics
>> traffic
>>
>> Christian
>>
>>
>> Le 04/07/2011 15:33, Matthias Brumm a écrit :
>>
>> Hello!
>>
>> At the moment I am monitoring it with top on UNIX shell, do you have
>> another suggestion? In top this process is idleing.
>>
>> Regards,
>>
>> Matthias
>>
>> 2011/7/4 Christian <cdebalorre at neotelecoms.com>
>>
>> Hi,
>> Try to monitor the fwdd process - when running high it causes packet to
>> drop on these pc's.
>>
>> Christian
>>
>>
>> Le 04/07/2011 13:11, Adam Leff a écrit :
>>
>>  I realize this will sound silly, but have you checked for half-duplex
>> on your interfaces?
>>
>> Those onboard J6350 interfaces are actually 10/100/1000, so if you
>> don't have the speed and link-mode hardcoded,  do a show interfaces
>> extensive ge-0/0/# and check the link partner section to ensure you're
>> running full-duplex.
>>
>> Adam
>>
>> On Jul 4, 2011, at 7:01, Matthias Brumm<matthias at brumm.net>  wrote:
>>
>>  Hello!
>>
>> Since some weeks now, we have a strange packet loss on one of our edge
>> locations.
>>
>> A few days ago an IX informed us about packet loss on our router. The
>> router
>> in place is a J6350. We have a 1 Gig line to us and two 1 Gig lines to
>> some
>> uplinks. Every communication goes through a 1 Gig copper link to a
>> ProCurve
>> 2810-24G. So the external links are connected to the switch and the switch
>> via one cable with the router.
>>
>> The packet loss is strange, because:
>>
>> 1. In smokeping during the busy hours of the day, there are losses of
>> about
>> 5%
>> 2. From my workstation I get packet loss of about 10 up to 50%
>> 3. There are no errors on the switch or router interface (except i.e. VLAN
>> errors)
>> 4. no customers have reported any problems. But there are many customers
>> relying on real time communication (VoIP/RDP)
>> 5. The switch port with the router is showing maximum 200 Mbit
>> 6. The router is showing 20% real-time threads
>>
>> According to the datasheet the J-Series should be able to deliver this
>> performance easily. Or are the onboard Gig-Interfaces the problem? Of
>> course
>> I know, that this physical configuration is a bad idea, and I will change
>> is
>> very soon to ease the load on this particular port.
>>
>> Any other ideas?
>>
>> Regards,
>>
>> Matthias
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