[Asterisk-Users] Bandwidth: to seperate or not to seperate

Derek Conniffe derek at rivertower.ie
Thu Feb 9 02:01:17 MST 2006

Hi Rich,

Thanks for replying to this question - the decision is confusing me a lot :)

You said:
"Help us understand exactly what this "incoming traffic flooding the
bandwidth" is suppose to mean. Are you running something else besides web
and voip through this link?  If not, then what is "flooding" your 

You are right about web page serving not using much incoming bandwidth (good for one-sided QoS management).  I was inaccurate by saying "hosting webpages" - we also have all email traffic and host racked servers for customers of ours too (and I have them on a lower QoS in the Netfilter/Wondershaper setup).  Actually, typically, the servers are business customers and probably don't use much bandwidth at all but I can't be sure that one of them would not, at any time, upload data from their mega-high-speed office connection - its a bit of an unknown.

It's a bit of a bummer that inbound traffic shaping cannot be done - considering that its a data-center setup as opposed to an office/home setup (kind of a so-close-but-so-far type thing).

Thinking about it now, before paying money for something we don't need, I should probably try to graph bandwidth usage (which opens a can of worms too - I'm used to MRTG but it would only show a 5 minute average and not instant peaks that would affect VoIP quality - have you ever used any other graphing tools?).

I remember when I first started playing with Netfilter & TC for QoS I was really surprised to find that very few people seem concerned with QoS routing which is amazing.

Thanks again for your opinions!


Rich Adamson wrote:

>>RE: Bandwidth.  We have an asterisk server sharing bandwidth with other 
>>[web] servers in cabinets that we rent in a large data-center and all is 
>>working fine.  But I'm concerned that web traffic could affect the VoIP 
>>quality (my tests so far haven't showed this [yet!].  Currently I'm 
>>running a server with Netfilter (iptables) between all the servers and 
>>the Internet with Forward rules and I'm also including a "wondershaper" 
>>type QoS ruleset with TC to priortise the outgoing VoIP traffic (I say 
>>outgoing because this is really the only thing I can shape on the 
>>connection as far as I can see).
>If your web server is oriented around simply serving up static pages with
>no one "uploading" data to it, then the majority of the web traffic will
>be outbound traffic. (eg, user clicks on a link, small amount of inbound
>traffic to communicate that click, followed by lots of outbound traffic
>reppreenting the new page(s) to be viewed.)
>The wondershaper function should prrioritze that mix of traffic just fine.
>>My choice, going forward, is to either buy more bandwidth and magically 
>>implement better QoS or the other option is to bring in a separate patch 
>>cable, with separate bandwidth, and a different IP address range 
>>directly to the asterisk and dedicate bandwidth to it and it alone.
>The above is certainly possible, but probably not the most cost effective
>use of total bandwidth. Based on the words provided, the single link
>bandwidth should be sized to handle the maximum number of voice channels
>to be used plus a small amount for web traffic. 
>>In a way the sharing of bandwidth with QoS would appear to be the better 
>>value option but I can't see that the TC QoS can really be up to the 
>>task (again partially this is because I can only control the outgoing 
>>traffic shaping - there is nothing I can do about the incoming traffic 
>>flooding the bandwidth).
>Help us understand exactly what this "incoming traffic flooding the
>bandwidth" is suppose to mean. Are you running something else besides web
>and voip through this link?  If not, then what is "flooding" your 
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Derek Conniffe
Rivertower Ltd
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