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

[Gary Stainburn]

On Wednesday 18 Aug 2004 9:53 am, Rik Wade wrote:
> > 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.

I don't think that the traffic's a problem but it's worth checking out.   I
don't know what MTRG is, but I'm asuming it's some form of network analyser.
As the existing switch connects directly to the bridge link, surely anything
listening would miss most of the traffic?

>
> > 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.

Sorry. The setip is:

A -> link-> B -> link -> C

> 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.

I've been quoted for some Cisco Layer 3 switches by the telco providing the
links, but after adding installation etc., they're talkingover £8K.

Personally, I've no ideas what I'm looking at here, but something like

http://www.pcwb.com/servlets/Catalogue?id=(463671)&shop=PCWBD

looks like it can do the job for a lot cheaper price.  Anyone know why I
shouldn't get something like this?

--
Gary Stainburn

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