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

[Jim Jackson]

I've not yet done QoS, but am aware that it is possible at layer 2.
We make extensive use of Cisco 2950 switches - there are several models
Goto the cisco web site www.cisco.com for details - I think the cheapest
is a 24 ports 10/100 switch - can't say what they would cost you, but I
believe quoted list is near 800 UKP - a decent cisco supplier should be
able to give you a discount.

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a008007e8de.html

details how you do QoS and setting up QoS on a 2950 switch. You may need
the enhanced software image not the standard one.

hope that helps :-)
Jim



On Wed, 18 Aug 2004, Gary Stainburn wrote:

> 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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