[j-nsp] Junipers and broadcast storm issues

[Mark Johnson]

Hi,

I've set this up in the lab and can replicate the problem by simply looping 
a couple of ports on a connected switch with spanning tree disabled. OSPF, 
BGP, fail.

Interestingly, I connected an old 7200 NPE-200 (admittedly at 100Mb while 
the Juniper is at Gig) and while its CPU hit 99% it stayed up and ran fine.

I guess the issue is that the crap coming from the switch is going to the RE 
and the internal PFE-RE 100Mb link is getting saturated (as with the MPLS 
vulnerability released today). There is a default arp policer in place and I 
did try setting my own at 3Mb/s with no difference so the crap isn't simply 
arp packets.

Can anyone give any pointers please (especially someone from Juniper)?

Kind regards,

Mark


>> -----Original Message-----
>> From: Mark Johnson [mailto:juniper-nsp at avensys.net]
>> Sent: 06 February 2005 22:54
>> To: juniper-nsp at puck.nether.net
>> Subject: [j-nsp] Junipers and broadcast storm issues
>>
>>
>> Hi,
>>
>> I'm a little disappointed so far in the way my M7i's handle
>> broadcast storms
>> at peering points. I'm hoping someone on the list could
>> enlighten me if this
>> is normal or if I can improve my config.
>>
>> Previously, with Cisco 7200 routers, I have seen increased
>> CPU on the router
>> during such events but it has never impacted traffic flowing
>> through the
>> router.
>>
>> The first broadcast storm was when an IXP's link went
>> unidirectional. It was
>> a FE port. Our monitoring system showed that a few ping tests
>> that went
>> through the affected router were dropped. I raised a ticket
>> with Imtech who
>> provide support but couldn't provide any reason for packets
>> passing through
>> the router to be dropped. They just pointed out that all the packets
>> arriving would need to be processed by the RE and this might
>> max out the RE
>> or the link to the RE.
>>
>> The second storm was on a GigE port when an IXP had a port
>> looped by a
>> member. The event was a little longer than the first one and
>> the effects a
>> bit more severe. MRTG 5 minute average showed that the port
>> received about
>> 70Mb/s and 140kpps. MRTG also showed that the RE/FE CPU
>> utilisation only
>> increased marginally and stayed below 20%.
>>
>> Our monitoring system showed that traffic flowing through the
>> router was
>> degraded. The routers logs showed no OSPF or BGP drops (other
>> than those to
>> the affected IXP) and there were no other entries whatsover
>> in the router's
>> log.
>>
>> Any advice appreciated.
>>
>> Kind regards,
>>
>> Mark
>>
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