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New Member

IP SLA Issues

Hi all,

I'm having an issues with a IP SLA I created which is controlling a static route. It works but is a little unreliable.

ip sla 1

icmp-echo 87.85.165.76 source-interface Vlan2 (this is a static host I use)

timeout 20000

threshold 2

frequency 30

ip sla schedule 1 life forever start-time now

Periodically when i run "sh track" it shows last change x minutes ago rather than days. The overall status appears to be "up" however.

Track 100

Response Time Reporter 1 reachability

Reachability is Up

15 changes, last change 00:03:23

Latest operation return code: Over threshold

Latest RTT (millisecs) 39

Tracked by:

STATIC-IP-ROUTING 0

Is there a way I can make this less sentative - I would ideally like it to only declare "down" after 30 secs with timeout of 20000 to rule out a flapping link?

9 REPLIES
New Member

Re: IP SLA Issues

mate you have put the frequency 30 ......its in seconds so after every 30 second it will query.....change that and you will be fine

hope it helps

New Member

Re: IP SLA Issues

Posted by: rasoftware - 244 Fulwood road

Jan 2, 2009, 8:05am PST

Hi all,

I'm having an issues with a IP SLA I created which is controlling a static route. It works but is a little unreliable.

I originally had it set to 15 but it seemed worse.

Do I understand this correctly -

Target- icmp-echo 87.85.165.76 source-interface Vlan2

Timeout - timeout 20000

Number of failures - threshold 2

Every x seconds - frequency 30

So every 30 secs, request ping within 20000ms, if two fail (threshold) - declare it down?

I always see to have this line in sh track

Latest operation return code: Over threshold

Re: IP SLA Issues

Use the delay command in the "track" part of your config:

delay (tracking)

To specify a period of time to delay communicating state changes of a tracked object, use the delay command in tracking configuration mode. To disable the delay period, use the no form of this command.

delay {up seconds [down seconds] | [up seconds] down seconds}

no delay {up seconds [down seconds] | [up seconds] down seconds}

More info:

http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_prb_mult_track_ps6441_TSD_Products_Configuration_Guide_Chapter.html

Hope that helps.

Cheers,

Martin

New Member

Re: IP SLA Issues

Hi Martin,

Thanks I worked this one out - it's been up for 3 days now without reporting a change using the delay up 10 sec down 30 secs.

Stability is key for my config and I only want failover if it been down for a minute or more.

It is much more stable now.

Thanks for the reply.

Re: IP SLA Issues

Hi,

Your Question:

Is there a way I can make this less sentative - I would ideally like it to only declare "down" after 30 secs with timeout of 20000 to rule out a flapping link?

Declare down after 30 seconds:

Command "frequency 30"

Rule a flapping link ?

Commadn " timeout 20000" (not sure that what is defined"

-----

Remove the static route if the link is down more than 30 seconds and not flapping.

The flapping can occur in minutes and you link may be up for 5 min and then again down or may be down in 1 min 2wice.

------------

This works great for me 5 min.

Paramites needed:

num-packets 3

frequency 300

remove

timeout 20000

threshold 2

When the route goes off. This will wait for 5 min down to replace the route.

So if your link flaps in this 5 min it will shift to backup unless it gest 3 packests in 5 min probe.

Once its down. It changes it route.

Now best part it will stay on the other route unless gain it recives prove of 5 min stable 3 packtes from the icmp-echo ip.

so if the link flaps on icp-echo ip provided it will not relace the route. Once the link is stable it will replace the route.

Downtime not more than 5 sec,

But for the first swicth over it depends on the frequency.

do decide about the frequesy you need to set.

Hope this helps

Regards,

pravin

New Member

Re: IP SLA Issues

Thanks Pravin,

I think i've cracked it with the 20000ms, freq 30sec, threshold 2.

Adding delay down 30 sec up 10 has prevented the status changing.

I believe if it missing two pings of a very high latency in 60 sec - it then starts count down - so a max 90 sec before failover. This seems to prevent "flapping" of the route due to a few missed pings when the link is really fine.

The sh track now corresponds to the router uptime, before I was getting a status change every 5 mins or so when the link was fine.

Since I have a VPN working over it - this was causing the tunnel to drop etc which is not good for the terminal users behind it.

I will investigate the "num packets" line as this might provide further more accuracy. I suspect my one just sends a single ping each 30 secs rather than 3 which should provide less false positives

Re: IP SLA Issues

Thats good to know that the problem is solved.

New Member

Re: IP SLA Issues

Hello Guys,

Do you have any idea on how to clear the "show track" statistics?

MOE#show track

Track 1

Response Time Reporter 1 reachability

Reachability is Up

57 changes, last change 10:14:49

Latest operation return code: OK

Latest RTT (millisecs) 40

Thanks,

Georges

Re: IP SLA Issues

hi,

copy the output for show run sla monitor xxx

config t

no sla monitor xxx

check track it will be 0

then paste back the configs for sla monitor 123

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