Codec Bandwidth Calculation

[Kosh76]

We are in the process of linking or remote sites with a layer 3 MPLS links. The main office has a 1G connection and out of it 5MB is configured as EF. The rest of the sites are on 200MB links with 1MB EF. We hope to mark all Voice Traffic as EF (DSCP 46).

My quesiton is simple: How many g711 calls (conversations) can I put on a 5mb (ef) link? Even though G711 is 64K -22k overheads = 87k (approx). When calculationg bandwidth you x2 87K = 174k (approx).

1. When calcualting bandwidth, do you calculate bi directional for a coversation?
2. How many calls can happen simulteneously on a 5mb link?
3. If the link is full duplex, will this rule change.

Appreciate any help and explanation.

 

[telcodog]

For G.711 codecs, use 100kbps for each call. It's actually a little less than that but that's the accepted rule of thumb. So technically you can have 500 simultaneous calls on on 5Mbps link.

That being said, bandwidth is not the only issue you look at. Latency is the big one, but if you have QOS control from end-t-end you should be OK.

 

[Kosh76]

Really? I thought you can only have a bout 50 calls

http://bostonvoicenet.com/blog/2011/03/qa-how-many-sip-calls-can-a-t1-circuit-handle/

 

[phoneguy610]

I think his math was a little off 50 is the correct number.

you can also use g 729 if available, that only uses about 10k

from what I have seen g.729 uses closer to 80k but it is a good rule of thumb to overestimate a bit like mentioned above

and it is the same bandwith up and down so if that mpls is 5mb one way but only .5 the other, you need to take that into account

ddcommllc.com
Avaya/Toshiba/SyntelSolutions

ACIS

"Will work for stars

 

[telcodog]

Sorry, I meant to type 50!