01-02-2009 08:05 AM - edited 03-04-2019 03:18 AM
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?
01-02-2009 08:24 AM
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
01-02-2009 08:31 AM
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
01-06-2009 04:16 AM
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:
Hope that helps.
Cheers,
Martin
01-06-2009 04:21 AM
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.
01-06-2009 06:36 AM
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
01-06-2009 07:34 AM
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
01-06-2009 11:08 PM
Thats good to know that the problem is solved.
02-03-2009 03:06 AM
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
02-03-2009 04:18 AM
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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