I'm trying to guage network performance using the UDP-jitter and ICMP-jitter operations for a specific network segment. We have a voice encoders that stream the audio over IP using UDP across the network. The issue we are experiencing is out-of-sequence packets; these packets show up as artefacts on the receiving end audio output. I understand that UDP is a connectionless protocol that doesn't provide any mechanism for sequencing. This is where teh SLA monitors come in.
I'm seeing statistics across the monitors that are inconsistent with each other. They aren't off just a little from each other; they are off quite a bit. The UDP-jitter operation (40006) isn't reporting any out-of-sequence packets (I can only see the last two hours, so I just changed the history to 24 hours). Operations 40001 and 40002 (ICMP-jitter) seem to report no packets as out-of-sequence or all packets as out-of-sequence. Operation 40002 is reporting around 50% packet loss. This is a false report. Operation 40006 is reporting 0% packet loss and the CODECs would be unusable if this were the case. Operations 50001 and 50002 were just configured so I don't have much history on them. Operation 50001 seems to be running clean, but 50002 has a lot of unprocessed packets.
You may have noticed that the operations that traverse the satellite link have a TOS of 172 (DSCP 43). This is done to ensure the the SLA monitor doesn't step on the CODEC traffic (DSCP EF, which is assigned to the LLQ). That's not to say that the traffic isn't prioritized; it is guaranteed bandwidth across the link. Also, there is no congestion on the network. I have also checked QoS policy-maps and there are no drops for the assoiciated queues. The circuits are up and stable. One circuit is a little dirty, but it the error rate is pretty low 0.003%.
So, my question is two part:
1. Why am I recieving out-of-sequence packets?
2. Has anyone else had this problem or a similar problem with the ICMP-jitter operation?
I have included a basic diagram and the statistics I have been able to collect thus far.
