[j-nsp] juniper m5 and flapping pings

[Boris Mimeur]

Hello harry,

I've already experience this kind of behaviour on Juniper routers (not 
too much loaded neither on CPU nor on bandwidth usage).

If ICMP traffic is low-priority, may you tell us which kind of traffic 
is high-priority and maybe the different priority level within a Juniper ?

Does JunOS use any of the FreeBSD kernel options like ICMP_BANDLIM or is 
it more complex than that (it makes sense if we consider this is the 
kernel which sends echo request - if you ping from the router - or 
receives echo request - if it's the target of the ping - ) ?

Following my own results looking like the ones from Florian, it's not 
very obvious to understand when the priority occurs, from my 
understanding it's not rate-limiting, so if it's queueing how does it work ?

Regards,

Boris


Harry Reynolds wrote:
> You should try pinging through the box. Locally generated ICMP traffic
> is low-priority and may experience significant jitter. There is no way
> to alter the priority (or lack of) in JUNOS software, so the best bet is
> to generate the traffic elsewhere.
> 
> HTHs.
>  
> 
> 
>>-----Original Message-----
>>From: juniper-nsp-bounces at puck.nether.net 
>>[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of 
>>Florian Taeger
>>Sent: Monday, March 28, 2005 5:50 AM
>>To: Erdem Sener
>>Cc: juniper-nsp at puck.nether.net
>>Subject: RE: [j-nsp] juniper m5 and flapping pings
>>
>>I'm pinging via the box ... I tried different servers ... 
>>everywhere the same problem. I even changed switches etc. It 
>>must be the m5 causing this problem.
>>but why ...
>>
>>Regards
>>
>>Florian
>>
>>Quoting Erdem Sener <erdem.sener at borusantelekom.com>:
>>
>>
>>>Hi Florian,
>>>
>>>Are you pinging 'from' the box itself or "via" the box? In 
>>
>>case you're 
>>
>>>experiencing this "from" the box, you should check whether 
>>
>>if you have 
>>
>>>logging enabled on a firewall filter applied to interface(s).
>>>
>>>You could also do a "show chassis cfeb" and check the CPU status.
>>>
>>>Cheers,
>>>Erdem
>>>
>>>
>>>>-----Original Message-----
>>>>From: juniper-nsp-bounces at puck.nether.net
>>>>[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Florian 
>>>>Taeger
>>>>Sent: Monday, March 28, 2005 4:37 PM
>>>>To: juniper-nsp at puck.nether.net
>>>>Subject: [j-nsp] juniper m5 and flapping pings
>>>>
>>>>Hi everybody,
>>>>
>>>>I'm just experiencing some very strange behaviour of a m5 
>>
>>router. The 
>>
>>>>router is used to speek bgp with around 200 peers and with 3x 
>>>>1000Base-SX and 4x 100Base-TX interfaces.
>>>>Everything seems to work properly, but every 45 to 60 seconds the 
>>>>pings to all external targets jump up to 40ms (or even
>>>>80ms) for some ms. Then everything works fine again at <5ms.
>>>>I tried to change the chassis to a m10 but the problem itself does 
>>>>not disappear. I even changed the pics, but again the 
>>
>>problem did not 
>>
>>>>disapear. I don't think the router engine causes this problem - 
>>>>everything else workes fine (routing itself, ...).
>>>>
>>>>So I'm not quite sure what could cause this behaviour. The 
>>
>>router is 
>>
>>>>at a cpu load < 30% ...
>>>>
>>>>Does anyone of you know this issue? Any suggestions? I do 
>>
>>not have a 
>>
>>>>spare routing engine, so I'm not able to change this part at the 
>>>>moment. Everything else (chassis, pics) were changed in the past - 
>>>>without any change of the problem.
>>>>
>>>>Best regards,
>>>>
>>>>Florian
>>>>
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