ChrisB

I've spent half my day trying to get some IP SLA (VoIP UDP jitter) monitors working in IOS with no joy. I've got icmp-echo working but want the additional stat's the jitter tests can provide.

Anyone got these working on routers before?

HHxx

Sorry Chris, I have never looked into that. We use a package called Prognosis that seems to do all that for us.

Saw something funny today that I haven't seen before. Fired up a Cat 4500 and saw this:

ROM: 12.2(44r)SG3
Darkside Revision 4, Jawa Revision 20, Tatooine Revision 140, Forerunner Revision 1.74

P1Fanatic

I only use the icmp-echo for HSRP tracking of ethernet WAN reachability so have not used it for Jitter. Do you have an issue with the configuration itself or the showing of the jitter stats?

I guess you already checked Cisco.com but in case you havent I found this page which mentions that you need to enable a responder on the target device before you can configure a jitter operation on the monitoring device:

http://www.cisco.com/en/US/prod/coll...cd804fb392.pdf

Cheers
Simon

hodgy0_2

not something basic like making sure debugging/monitoring is enabled and writing to the correct terminal

ChrisB

Thanks guys.

I've got a beefy Cisco document - 270 pages for a little bedtime reading.

The setup I'm trying to get it working on is a triangle of routers, with a VPN tunnel between each. I've tried adding "ip sla responder" but that didn't work, so I've also tried "ip sla responder udp-echo <ipaddress> port <port>". The Cisco doc's doesn't make it clear if the <ipaddress> should be ip address of the router sending the probe or the router which is the responder. I've tried both and it didn't work - one probe reports a timeout, the no-connection.

I'm not sure all is happy lower down the config though. I can ping from one router to the other, but I if traceroute from one router to a device behind another router (over the VPN), the first hop times-out and the 2nd hop is the device replying.

hodgy0_2

is icmp enabled on the first hop device?

ChrisB

Possibly not - do you need "permit icmp" in the VPN ACL? Or is:

access-list 105 permit ip 192.168.10.0 0.0.0.255 192.168.20.0 0.0.0.255

enough?

hodgy0_2

do you have physical access to these devices

if you don't -- i.e. some are remote devices you might want to use the "reload in" command

especially if you are playing about with ACL's -- as you can loose connection -- but if you have set the "reload in" command to say 20 mins -- the router will reboot with it's original configuration and you will be able to re-connect

after a successful ACL change just undo the reload command

also what I would say is that VPN is a point to point technology, so you will not be able to ping any intermediate devices using the VPN tunnel

P1Fanatic

permit ip will be fine as encompasses all IP protocols including ICMP.

Can you ping that device behind your 2nd router as you mention you can ping between the routers but then change to tracing to the device behind.

Going back to the IP sla responder - if you check the link I posted it says you just configure using the command "rtr responder". Just tried this myself and looks like its a hidden command as not listed nor can you tab it out:

uuk205607-gw#conf t
Enter configuration commands, one per line. End with CNTL/Z.
uuk205607-gw(config)#rtr responder
uuk205607-gw(config)#^Z

It then adds this line to the running config:

ip sla monitor responder

Cheers
Simon

ChrisB

Thanks for the tips Hodgy.

I've just picked up a 2651XM and a 2611XM (both 12.4 Advanced IOS) on eBay so I can test on my desk rather than on remote ADSL routers.

Simon, this is my SSH session on the router 192.168.10.1:

Going to leave the IP SLA till my little test setup arrives but I'm intrigued as to why the traceroute dies on the first hop.

hodgy0_2

No worries Chris

you only make the mistake of locking yourself out of a router halfway across the world -- and have to ring the DataCentre to get it rebooted once

P1Fanatic

Or set the reload in xxxx, make your change without losing connection then get distracted with a phonecall etc only to realise you forgot to cancel the reload and the device reboots

Ive managed that at least a couple of times lol

Simon