Re: [load balancing] F5 LTM marking nodes down

From: Omachonu Ogali <oogali [izzat] gmail.com>
Date: Wed Nov 07 2007 - 12:22:18 EST

Not necessarily, as you can limit the filter to only capture traffic
generated by source and destination IP pairs of the standby unit and
the server, which should bring up a small amount of data.

Even if they're doing SNAT automap, there will still be next to no
traffic on the standby unit, because it's in standby.

oo

On Nov 7, 2007 11:42 AM, LeMay, John <JLeMay@khov.com> wrote:
>
> I agree, however increasing those timeouts may hide the issue or as I
> stated possibly indicate a timing issue. The trace is ideal, but
> depending on how much traffic is going through the device that may be
> like looking for a needle in a haystack.
>
>
> --
> John LeMay
> K. Hovnanian Companies, LLC
> Systems Engineer
> Ph. 732 383-2195
> jlemay@khov.com
>
> -----Original Message-----
> From: lb-l-bounces@vegan.net [mailto:lb-l-bounces@vegan.net] On Behalf
>
> Of Omachonu Ogali
> Sent: Wednesday, November 07, 2007 11:22
> To: Load Balancing Mailing List
> Subject: Re: [load balancing] F5 LTM marking nodes down
>
> But if the issue was the frequency of the monitor, he would be seeing
> intermittent up/down events from both units, not just the standby. A
> network sniff is really needed to see exactly what is going on.
>
> oo
>
> On Nov 7, 2007 10:48 AM, LeMay, John <JLeMay@khov.com> wrote:
> >
> >
> >
> > A possible resolution, really a workaround, may be to use custom
> > monitors for http and icmp with increased timer and interval values.
> > I've done this in the past for different reasons, and it doesn't tell
> > you where the issue is of course. If you do go this route, F5 has
> > recommended to me in the past that the timeout should always equal
> > three times the interval plus one second (the online help recommends
> > the same). This may even give a clue to the root cause of the issue.
> > If you increase the timeout and interval and the issue goes away,
> chances are the issue is latency of some sort.
> >
> > If you can get this to happen at predictable times, you could always
> > run tcpdump on the standby box during that time period and see if
> > there are any clues in the trace.
> >
> > --
> > John LeMay
> > K. Hovnanian Companies, LLC
> > Systems Engineer
> > Ph. 732 383-2195
> > jlemay@khov.com
> >
> >
> >
> > ________________________________
> >
> > From: lb-l-bounces@vegan.net [mailto:lb-l-bounces@vegan.net] On Behalf
>
> > Of Julian Grunnell
> > Sent: Wednesday, November 07, 2007 10:14
> > To: lb-l@vegan.net
> > Subject: [load balancing] F5 LTM marking nodes down
> >
> >
> >
> >
> > Hi - got a query regarding alerts that a STANDBY LTM 1500 is
> > generating, we have a pair of LTM 1500's in an ACTIVE / STANDBY setup
> using vlangroups.
> > Version 9.3.0 is installed. The nodes behind the LTMs are Microsoft
> > 2003 IIS 6.0 servers using ACTIVE / PASSIVE NIC teaming.
> >
> > We see on a daily basis the STANDBY LTM marking nodes as DOWN and then
>
> > UP for both icmp and HTTP health checks, often a minute or two
> > inbetween the state changes, the ACTIVE LTM NEVER logs anything.
> >
> > At the times the alerts are seen the guys that admin the web servers
> > cannot see anything wrong at all - the servers are up and running. And
>
> > the guys that admin the network infrastructure cannot see any errors
> > at all from any of the switchports. What I have seen is that when the
> > STANDBY LTM has the node marked DOWN I can both ping the node in
> > question and make a port 80 connection from the STANDY LTM which is
> just bizarre.
> >
> > If anyone has any ideas on where the problem might lie, things that
> > would be worth checking or even better have had this problem before
> > and how to resolve it I would appreciate it!!
> >
> > Thanks - Julian.
> >
> >
> > Julian Grunnell
> > 3rd Line Technical Support
> > Pipex Communications
> >
> > Tel: 01296 300227
> > Mob: 07803 649593
> > Web: http://www.pipex.com/
> >
> > This e-mail is subject to: http://www.pipex.net/disclaimer.html
> >
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Received on Wed Nov 7 12:22:46 2007

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