[cisco-voip] QoS in distributed cluster

Tue Dec 13 07:51:10 EST 2005

As they say, 'it depends'.  If your links are saturated, you have to pay extra
attention to how you play with your traffic.  If not, then it isn't quite so
bad.  Are you running more than 10 mbps thorugh your primary links?  If so,
then you really need to pay extra attention to the
class-map/policy-map/service-policy configurations for bandwidth, policing, and
shaping on the devices in the 10mbps links.  Again Cisco's DQOS books go into a
fair amount of detail on how to do this, especially with how to deal with
congestion in networks.  As experiementation, you can even rate-limit your
100mbps links to 10mbps to simulate what will happen on your 10mbps links.

You've also checked that your WAN links are all full-duplex and are configured
as such, and are working with zero errors?

The idea though is that you can not 'set and forget'.  You have to monitor and
test your configurations.  Commands like 'sho policy-map interface ..' help you
identify what is happening with the various queues.

When setting priority queues, various switches have various number of egress
queues, with the priorty queue not always being the same.  You'll have to did
through Cisco's documentation to work out the specifics.  Some of the DQOS
course notes help with a number of your switch types.

Using NBAR and SLA/SAA in conjunction with Cricket and some third party config
help you monitor in-depth the QoS portions of your configs to see what is
getting through and what is getting dropped.

Quoting Ruben Montes <Ruben.Montes at eu.didata.com>:

> Thanks for you response.
> 
> Yes, I'm using L3 in the devices: MSFC3 in the 6500, the 4232L3 in a
> 4006 with CatOs and a C4506 with L3.
> Now, my RTT aprox is 12ms, but I would like to configure QoS in all the
> network to have all the voice and intra-cluster traffic controlled.
> 
> I would use autoqos in the C45006 because this is the only device that
> supports that functionality. I would do a similar mapping in the 4000
> and the 6500. Do you think it would be enough?
> 
> Regards,
> 
> Ruben
> 
> -----Mensaje original-----
> De: Ray Burkholder [mailto:ray at oneunified.net] 
> Enviado el: martes, 13 de diciembre de 2005 13:10
> Para: Ruben Montes
> Asunto: Re: [cisco-voip] QoS in distributed cluster
> 
> Hi There,
> 
> As an AVVID practitioner, I would highly recommend you review Cisco's
> DQOS
> course notes and text book (if you havn't already).  They explain the
> queueing
> structures available in switches and how to configure them in light of
> prioritizing prec 3 and prec 5 traffic.  In summary though, with
> properly
> configured switch QOS, you would be making use of 2 or 4 or more queues
> in each
> switch type, and they take care of queueing requirements.  I find the
> auto-qos
> functions in each switch type very handy in figuring out the
> peculiarities of
> each switch.
> 
> In addition, for the WAN or MAN or WLAN that you have, are you using
> layer 3
> switching in the devices?  Recent Cisco best practices indicate that
> alot of
> segmentation is a good thing.
> 
> One more thing, for distributed clusters, Cisco requires that one way
> between
> callmanagers must not be more than 20ms, or 40ms round trip.
> 
> Many of the Cisco devices have SLA/SAA/RTT capabilities so you can
> monitor this
> in real time.
> 
> In addition, by using some Cricket addons, you can monitor your network
> wide QOS
> statistics quite readily for delays, jitter, drops, and losses.
> 
> Quoting Ruben Montes <Ruben.Montes at eu.didata.com>:
> 
> > 	Hello,
> > 
> > 	 
> > 
> > 	I have a distributed cluster. The publisher is located in one
> > city and the subscriber is in another one. The network is a LAN-to-LAN
> > with all L2 interfaces.
> > 
> > 	In the best case, there are two 100MB hops between the
> > CallManagers, and in the worst case (redundant path) two 10MB hops.
> I'm
> > a little bit worried about that and I would like to configure QoS. We
> > have a bunch of devices between the CCMs:
> > 
> > 	-         C6500 with sup720
> > 
> > 	-         C4500 with 4232L3
> > 
> > 	-         C3548
> > 
> > 	-         C4506
> > 
> > 	 
> > 
> > 	My question is if it enough to mark the interesting traffic and
> > map it to a high priority egress queue in all the path, or if it is
> > necessary to agreggate policiers to limit the traffc.
> > 
> > 	 
> > 
> > 	If I had a WAN I would configure CWFQ, but in this case, which
> > do you think is the best option?
> > 
> > 	 
> > 
> > 	Regards,
> > 
> > 	 
> > 
> > 	Ruben
> > 
> > 
> > -- 
> > Scanned for viruses and dangerous content at 
> > http://www.oneunified.net and is believed to be clean.
> > 
> > 
> 
> 
> -- 
> Ray Burkholder
> http://www.oneunified.net
> ray at oneunified.net
> 441 505 7293
> 
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-- 
Ray Burkholder
http://www.oneunified.net
ray at oneunified.net
441 505 7293

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