IP SLA never recovers after a failure.

[thomas947]

Pretty simple, using an IP SLA icmp-echo with HSRP for failover.

ip sla 1

icmp-echo 192.168.0.1

frequency 30

ip sla schedule 1 life forever start-time now

It works, unless the ping times out.  Once it does, it will never return a success again unless I delete the SLA and re-enter it.  This is on an 881 with IOS 15.0(1)M4.  I have tried a variety of timeout values, no luck. This does NOT happen on our routers running 12.4 with the same commands.  On those, the expected behavior occurs-the SLA returns success once the pinged IP is back up.  So the below output indicates 44 consecutive successes followed by 45 consecutive failures even though the IP is indeed returning a response.

IPSLA operation id: 1

Type of operation: icmp-echo

        Latest RTT: NoConnection/Busy/Timeout

Latest operation start time: 11:22:37.023 MST Fri Sep 2 2011

Latest operation return code: Timeout

Number of successes: 44

Number of failures: 45

Operation time to live: Forever

[Amit Aneja]

So, you are saying that the SLA stats keeps on incrementing the no. of failures even when you can ping 192.168.0.1 manually from the router?

[thomas947]

Yes, that is correct.  I am tracking the SLA, and the tracking output shows down even though the router can ping just fine:

Track 1

  IP SLA 1 state

  State is Down

    11 changes, last change 00:29:40

  Latest operation return code: Timeout

  Tracked by:

    HSRP Vlan1 1

Even though:

Sending 5, 100-byte ICMP Echos to 192.168.0.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 24/24/28 ms

[Amit Aneja]

Could you share the complete name of the IOS, license you have on the router?

Also, what is the source interface that you are using for this ping? Could you share the config of that port as well?

[thomas947]

I have tried using both interfaces as icmp-echo source, with the same results.  I do want to stress that this works fine, until the first failure.

Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.0(1)M4, RELEASE SOFTWARE (fc1)

License Information for 'c880-data'

    License Level: advipservices   Type: Permanent

    Next reboot license Level: advipservices

interface FastEthernet4

description WAN Interface

bandwidth 12122

ip address 192.168.0.2 255.255.255.252

ip access-group r2_in_acl in

no ip redirects

no ip unreachables

no ip proxy-arp

ip verify unicast reverse-path

ip flow ingress

ip nat outside

ip inspect r2_fw out

ip virtual-reassembly

duplex auto

speed auto

no cdp enable

!

!

interface Vlan1

description LAN Interface

ip address 192.168.1.2 255.255.255.0

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

ip nat inside

ip virtual-reassembly

standby 1 ip 192.168.1.10

standby 1 priority 106

standby 1 preempt

standby 1 track 1 decrement 5

standby 1 track 2 decrement 5

standby 1 track 3 decrement 25

[Amit Aneja]

It for sure looks like a bug to me, I looket at various bugs on 15.0 for IP SLA, but couldn't find a specific one that matches the behavior exactly. I am leaving for day. Will keep you posted if I find a matching bug or anything which could explain this behavior.

[ptoomath01]

I am having the same issue. Did you find a fix for this problem?

[thomas947]

Yes, an update to IOS 15.1(not sure exactly which revision) fixed it.

[ptoomath01]

Thanks Thomas,

Would be be able to find the version or perhaps a cisco Bug ID?

Would appreciate your help...

Peter.

Peter Toomath

Mobile 022 2234444

On 30 January 2012 17:51, thomas947 <

[thomas947]

The version that fixed the problem is

Version 15.1(4)M1

I am not aware of any Cisco bug ID for this.  I opened a case with TAC and this was the just the last thing we tried, just to see if it worked.