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Paul McGurn
Frequent Contributor

IP SLA on IOS 15.1 responders not working

I'm seeing a pattern when trying to use IP SLA udp-jitter configurations where the responder is running IOS 15.1.  In this scenario, I've verified 3 different routers all acting the same.  The "sh ip sla stat" command will output like this:

IPSLA operation id: 3Type of operation: udp-jitter

Latest RTT: NoConnection/Busy/Timeout
Latest operation start time: 17:33:17 est Sat Nov 17 2012
Latest operation return code: Timeout

I have a 3825 with IOS 15.1(4)M3 advanced enterprise, acting as the source/polling router for 5 other routers.

R1 is a 2851 running IOS 12.4(24)T1 advanced enterprise.  This works.

R2 is a 2821 running IOS 12.4(24)T3 spservices  .  This works.

R3 is a 2921 running IOS 15.1(4)M3 universal with the UC license.  This does not work.

R4 is a 2921 running IOS 15.0(1)M3 universal.  This works.

R5 is a 2921 running IOS 15.1(4)M4 universal with the UC license.  This does not work.

R6 is a 2801 running IOS 12.4(22)T2 advanced enterprise.  This works.

There are no ACL's in place, and connectivity is verified in both directions via ping and traceroute to be working as expected.

The config for each destination router on the 3825 is identical, except for the port, per the comments above.  I see the UDP port get opened on the target routers.  When running "debug ip sla trace 0" on the routers that do not work, it looks like the following happens:

  1. The 3825 sends a control message
  2. R3 acts on that message by opening the port identified in that message (16484) in my config.
  3. The port remains open for exactly 25 seconds
  4. R3 tears down the port

R3's udp-jitter config on the 3825:

ip sla 3 

udp-jitter <R3's IP> 16484 source-ip <3825's IP> codec g729a advantage-factor 2 tag *** Jitter test to R3 *** frequency 30
ip sla schedule 3 life forever start-time now

R3's IP SLA Responder config

ip sla responder

ip sla responder auto-register <3825's IP> endpoint-list autolist client-id R3

I will note that the configuration guide says to use either "ip sla responder" or the more detailed version like I have above.  The "ip sla responder" command is automatically added when you add the more detailed command.  I have tried R3 and R5 with just "ip sla responder" and with the more detailed syntax,

to no avail.  Both show as Registered when running "sh ip sla responder" locally.  At this stage, I can run IP SLA udp-jitter against anything but a router running on IOS 15.1.  I even tested this by configuring IP SLA on R3 to poll the 3825, and that also fails.

Can anyone confirm whether they've had success with this on IOS 15.1 as a responder?