How much bandwidth should you have for VOIP calls??

[SY]

if only voice traffi - then 20 call (upstream usage will be 80 kbps per call)

Ehhhhh, that is 20 voice paths that represents in 12 calls concurrent. Unless I am really wrong somewhere...... that can happen.

Henk, Could you please share your knowledge? Seems we speak about completely different things, isn't it?

P.S. I just cannot catch what is "20 voice paths that represents in 12 calls concurrent". Where do these "20 voice paths" represent "12 calls concurrent"?

 

[Ralph]

I am not getting somthing here

I have been monitoring my 3CX server network interface using perfomance monitor with the Network Interface -> Bytes Total/sec counter.

During a single 2 way phone call the amount of bandwidth used throughout the call never exceeds 44k in total.

Im using G711 with Polycom Soundpoint IP 501 phones. How am I not using the 160k total bandwidth your guys are talking about? Am I using the wrong counter?

Thanks again

 

[Anonymous]

I am revering to Voice Channels or also known as Erlangs. This is the amount of traffic that can be handled in an hour, using the BHT (busy hour).

Do a bit of a google, to explain the topic here will take a fair bit of posting. (I also do not understand it fully but you that is how things go).

 

[Anonymous]

Re: I am not getting somthing here

I have been monitoring my 3CX server network interface using perfomance monitor with the Network Interface -> Bytes Total/sec counter.

During a single 2 way phone call the amount of bandwidth used throughout the call never exceeds 44k in total.

Im using G711 with Polycom Soundpoint IP 501 phones. How am I not using the 160k total bandwidth your guys are talking about? Am I using the wrong counter?

Thanks again

Well is it Bytes or Bits your counting?

Aslo (to put this to bed) the 80k is the best to go buy (SY's numbers) see it all depends on so many things (give an take a few bits and bytes).

G711 is an uncompressed codec, with a max MOS score of 4.1 Which is pretty good quality, as a fact the best atm. GSM for example is 3.3/3.4 max.

The bandwidth required is depending on what transport layour you use as the payload either fits or does not fit in a packet. That is why G711 over ATM is asking for trouble.

Conclusion:
The exact bandwidth might not be relevant for what we use the system for, unless you go into 100's of calls at the same time you might want to look at your network config. But for the 10 odd concurrent calls you should have not many troubles.

If you want to know what 10 concurrent calls represent to in BW i would recomment do use the Erlang plus 5-10% to cater for the management stuff.

Hope this helps.
For now Ill settle with SY's numbers (I just been hassling him )

 

[Ralph]

Did QOS have a significant impact on your VOIP performance?

Good afternoon ITFarmer,

You mentioned that you had implemented QOS. Did this have a significant impact on your VOIP performance? Have you noticed a decrease in other performance areas as a result?

Thanks again

 

[Anonymous]

QoS is mainly to give VoIP priority above other traffic. This only plays if your network is maxed out.

I run a community network with voice, data and realtime video streaming. On bad days we flood our 54mbps for our wireless that is when you notice that you do not have any noticable delays.

Recently I moved VoIP to another network segment for testing and playing (trying to stay ahead of the rest of you guys, but that is getting harder I noticed ).

So conclusing, QoS does not make things go faster it makes things go smoother.

Hope that answers you question, keep in mind that all your elements in the network have to support QoS, especially on the edge.

 

[Ralph]

Thanks ITFarmer

Thanks ITFarmer,

I am leaning toward moving the VOIP to an entirely seperate network (seperate hardware, etc.) that will run paralell to our existing network.

After the dust settles a bit, I am going to take another look at our baselines. The way hardware prices are dropping this might be feasable.

Thanks again

 

[tjabaut]

That would really negate the benefits of moving to VoIP; running everything on the same backbone. If you are running into performance problems on your LAN chances are you need to employ some type of QoS to prioritize the VoIP traffic. You would assign your voice traffic the highest priority such as a 7 and give all other traffic say a 3.

You can also virtually partition your network with the use of VLANs. This is how we partition our networks if there is any congestion.