[j-nsp] M20 buffer fault?

[Michael Loftis]

--On October 27, 2005 7:40:58 AM +1300 Gordon Smith <gsmith at wxc.co.nz> 
wrote:

> Hi all,
>
> Just came across an odd problem with one of our M20's - I've got JUNOS
> 7.4 on there for testing at the moment. I noticed that the router had
> become unresponsive, and when I went and had a look at it, both RE's
> were online as masters.

That's a fairly common FreeBSD problem....but I was pretty sure that those 
items went dynamic late in 4.x series, or atleast the initial computation 
did...but...looking at my 7.3R1.5 M7i I see kern.maxusers: 32  -- however 
kern.ipc.nmbufs is reasonable at 101356 on my box, which indicates it's 
gettinc computed based on RAM.... however If you're seeing it you in theory 
can try and add

kern.maxusers=256

in /boot/loader.conf.local on both REs and restart.  Should force it to 
push up the number of mbufs allocated, no matter what the compile time 
setting is.  This tunable isn't available except at boot time, and I 
honestly have no idea if there's a 'Juniper' way of fixing that tunable up 
in loader.conf (which I think JunOS does maintain).  You also might want to 
try pushing it up in steps, 32, 64, 96, and so on and checking your free 
RAM from 'top' -- if you turn it up too high and there's not enough memory 
the system may not boot.

It does sound like you're getting some sort of max number of open 
descriptors.  mbufs are used for quite a lot of things.  NMBCLUSTERS is the 
compile time variable.

>
> In the logs, this is what was occurring right up until I reset the box:
>
> Oct 26 21:37:49  jcore2 /kernel: Out of mbuf clusters - adjust
> NMBCLUSTERS or increase maxusers!
> Oct 26 21:37:49  jcore2 /kernel: Out of mbufs (error count: 1)
> Oct 26 21:37:49  jcore2 /kernel: Out of mbufs (error count: 1)
> Oct 26 21:37:49  jcore2 /kernel: Out of mbuf clusters (error count: 1)
> Oct 26 21:37:50  jcore2 /kernel: Out of mbufs (error count: 1)
>
>
> At the moment, the router is split into logicals (for vertical
> aggregation), running BGP and IS-IS. Nothing really unusual. There are
> still some unconfigured peers, but I wouldn't think that unconfigured
> peers knocking on the door would cause resource exhaustion.
>
> Anyone have any info on this? It's not a fault I've seen before...
>
>
> Cheers,
> Gordon
>
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