VoIP packet loss not seen on Cisco switches?

[dvtestguy]

Have a VoIP gen tool able to generate 24k end-points (12k calls) to run into a Cisco lab network (See connection below), and the VoIP Gen tool claims that ports bandwidth is 100% for the Codec G.729 for each of the four ports connected.

VoIP Caller (ports 0-3) <--> 6506 (ports f4/17-20) <--> Gb Trunk to a 3550 <--> (ports f0/17-20) <--> VoIP Terminate (ports 5-8).

Problems seen are;
1. When I start this VoIP traffic generator (over the connected cisco ports via VLANs 100-103) I'm getting huge amounts of packet loss from my VoIP Gen and not seen on the Cisco ports.

2. Calls are not being connected due to obvious Packet Loss from the VoIP Gen, but not on the Cisco ports?

I can see the mac-address table increment (as expected) and no ARP entries (other than the mgt ip of the VoIP test device.

Am I missing something as far as;
-MAC-Addresses not releasing or exceeded the max amount?
-ARP entires exceeded?
-VLANs exceeded?
-Why wouldn't I see Packet Loss on the Cisco ports if my traffic-gen tool is reporting them?
-Would Ether-Channel work in this config?

Any ideas?

Thanks,

 

[burtsbees]

What is the QoS config that you have? How much bandwidth do you have dedicated for VoIP?

Burt

 

[burtsbees]

Oh---did you do a "sh int" on one of the problem ports, and it shows no drops?

Burt

 

[dvtestguy]

Hey Burt...

QoS isn't setup as I'm using VLANs to encapsulate the VoIP.

sh int doesn't show any drops...which doesn't seem right if the traffic gen shows substantial packet loss.

 

[burtsbees]

I am a bit braindead at the moment, so forgive me if I don't understand. Without prioritizing VoIP traffic, the bandwidth may be being used for different things, like video or data, not leaving enough for VoIP. The other packets are going through, so there are no drops on the interface. Your application would see dropped VoIP packets, because that is what it is designed to do---without QoS, the interface lets whatever go through with the default queueing mechanism, fifo (first in, first out). First come, first serve. I could be way off on this one, though,l since I am not quite sure about encapsulating VoIP traffic with vlans. What about "sh int vlan xxx" on the VoIP vlan?

Burt