(OT) Re: [Wylug-help] QOS over transparrent bridge using Linux?

[Rik Wade]

> On Monday 09 Aug 2004 10:13 pm, Gary Stainburn wrote:

>> Connecting the two new sites to the existing one are 10MB transparrent
>> bridges.  All 3 sites are using the same subnet and network traffic is
>> working fine.
>>
>> However, we have a problem with our switchboards, which use VoIP to
>> connect to erach other over the 10MB links.  Because the bridging is
>> transparrent, there is no QOS facilities, and the VoIP has to fight
>> with normal traffic causing the audio to 'Clip'.   Is there any way I
>> could use a pair of Linux boxen to proile the traffic and enable a QOS
>> facility?

Can you run MRTG against these bridges (or get other stats) to see what
the traffic levels are? You may find that the network is running a bit
"hot" to support VoIP. Can it be upgraded to 100Mb/s? Adding bandwidth is
often a cheaper solution than implementing QoS.
> The only response I got from this was one from Jim, suggesting that I
> look into using a managed switche, and suggested Ciscos.
>
> As this looks like the only solution, can anyone suggest a suitable
> switch - Cisco or otherwise - that will allow the priority of VoIP
> traffic over normal data.

> We have three sites in a daisy-chain setup, so three switches talking
> to each other would be needed.

Do you mean:

A--B--C

or
    A
   / \
  B---C

just being picky over the "talking to each other", which implies that they
are meshed.
A "clever" switch from someone like Cisco may well be the way to go, but
I'm not sure how you're going to implement the QoS at layer 2.
VoIP is just an application running over IP. The IP packets can be marked
with IP Precedence (or other such) markings. They can then be inspected by
a router and queued accordingly. This is, however, all done at layer 3.
I have no experience of doing LAN Ethernet QoS but understand that it can
be done. If you're looking at this solution be very sure to precisely
state your requirements to your equipment vendor. Googling for "ethernet
qos bridge" gave me some hits.
It would be dead easy to do at layer 3.
--
rik