Bandwidth Management on TZ-170...does it work? 1

[ajharn]

Hi,

I've got a TZ170 with ehahnced OS running the latest firmware. I have enabled Bandwidth Management on a rule to cover 4 inbound VoiP channels (sip traffic is coming from the internet. I'm running on a full T1. And I've been told that each VoiP channel only uses a max of 64K. I have enabled BWM on my VoiP access rule and I have ramped it up to as high as 75% guaranteed inbound bandwidth (90 Maximum). But it seems to have no effect. If I download a large file then call in on the VoiP line, the voice quality is poor. When there is normal (low)traffic on the T1, call quality is good.

When a single call is in progress, the BWM tracking reports that only about 5-6% of bandwidth is in use.

The BWM doesn't seem to be doing its job as advertised. I'm not sure how proceed. Any advice would be appreciated.

Thanks,
AJ

 

[joepc]

I think you also need to enable it on the WAN interface and specify how much bandwidth you have before you can manage it.

 

[ajharn]

Thanks, Joe. I had already enabled it in the WAN interface. You have to do that before you can turn it on for any rule.

I've been back and forth with Sonicwall about this. They've logged in remotely and we've tried several configurations. The bottom line, is that guaranteeing bandwidth is not enough. For instance, I guaranteed the traffic 50% of the bandwidth...the traffic only actually uses 6% of the bandwidth. So the TZ-170 allows other non-voip traffic to use the other 94% anyway, since the VoiP doesn't need it. But VoiP packets immediately start dropping in this case.

So I had to manually, reflexively throttle other traffic to guarantee more availability for the VoiP. So I had to create rules on HTTP and other traffic types that set their MAXIMUM bandwidth.

This essentially worked, but even when HTTP is only allowed to use 20% of the bandwidth and a VoiP Call is only using 6% of the bandwidth, VoiP data still drops to a lesser extent. I think it comes down to the TZ-170 just not having good enough throughput.

Yes, QoS is enabled with DSCP marking and VoiP traffic marked top priority and all other traffic given lower priority. No, I don't have any UTM services putting further load on my CPU.

I will probably have to dedicate a second WAN connection to the VoiP calls, as I expect a need to expand in the future. As is, my current config works alright, because I have very little traffic to interfere with the VoiP at most times.

But for others dealing with this issue. The key is that Guaranteeing bandwidth for your VoiP services is not terribly effective. You need to create rules for all other services and throttle their "Maximum" bandwidth.

Good luck to all.