tools for latency issues?

[hmc250000]

what tools are best recommended that can help idenitify slow routers or fiewalls with intermittent latency issues?

We are having jitter intermittently on voip calls possibly because of a lag in some hops

In a single trace (for example in windows) to a destiny it is sometimes hard to see which hop is causing the issues.

Pingplotter is helpful but not free.

[Joseph W. Doherty]

You might consider using a SLA test against each hop.

That, or any other synthetic test, though, won't really show the same results as might be happening to transit traffic on those devices.

Do you have QoS end-to-end (which is often a requirement for VoIP)?

[hmc250000]

Thanks, I think you brought up a good point. We have QOS enabled on all internal network devices. Our ISP however does not have it enabled. It worked fine that way for a long time. 

When I run pingplotter our firewall (sonicwall) and the ISP router show fused as one hop.That hop shows high intermittent latency spikes (2000ms) but I have hard time find out which one is the culplrit. 

i will have to find out how sla can be used to monitor jitter but don't know if it's worth investing my time for this. 

[Georg Pauwen]

Hello,

on a side note, I assume the SonicWall is the last hop under your control ? What QoS settings do you have configured on the SonicWall ? Does the firewall preserve the DSCP and/or 802.1p markings ?

[hmc250000]

yes, the sonicwall is the last hop on our internet network however i don't manage it nor do I have access to it. I was told QOS was configured (trust dscp). 

Would ip sla udp jitter be a good way to find out where the congestion occurs exactly? Would it be helpful if i configure it on the L3 switch on the internal network? If so how do I best do this?

Thanks.