[Asterisk-Users] Managed Switches QoS to deal with network bottleneck

[Mark Tinka]

On Thursday 02 March 2006 11:46, Dana Harding wrote:
> Good Day Everybody,

Hi.

> I'm convinced that a QoS-based approach is the way to
> ensure file transfers do not interrupt VoIP traffic.  
> (not to mention the fact that I don't want to have to
> dig a ditch in the ground to run another cable parallel
> to the existing link).

I've always said (I work for an ISP), apart from your 
customer and upstream links, what other links does a 
network expect to saturate? My basis for this thought is 
that local, core, internal bandwidth is cheap to install, 
maintain and upgrade.

Let's say your switches are "switching" Layer 2 frames 
like they should, are you already reaching 75% of the 
switch's switching capacity? Of course, the amount of 
bandwidth you can push through a single switch will 
depend on the vendor and model - but let's say you have a 
decent switch that can dos ome 80Mbps before it falls 
over, have you started hitting this already?

Let's look at your cabling - Cat-5 is generally good 
enough to run 100Mbps (sometimes 1000Mbps). Then again, 
you could run use fibre to interconnect the switches over 
a 1Gbps port trunk.

Either way, buying a switch that will do 10/100/1000Mbps 
per port including uplink ports, and support fibre uplink 
connectivity, is much better than trying to run QoS on a 
LAN. QoS has its own complications, but is really 
unnecessary on a well (read: over) engineered LAN; I 
think.

Just get yourself small 2950T Cisco switches (they have 2x 
1Gbps uplink ports), or a 3750 Cisco switch that has 
Gig-E support on all switch ports. Both are relatively 
inexpensive for the amount of bandwidth you'll achieve.

Cheers,

Mark.
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