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I need some guru help on this one.

I am dealing with several Wide Area Networks which have or are
implementing VoIP. Here is an example of a network:

Host Site = 1.5MB
Remote Site A = 512K
Remote Site B = 768K
Remote Site C = 512K
Remote Site D = 768K
Remote Site E = 960K

These are private circuits all brought back to a VLAN on the carrier’s
network (Layer 2).

The ones that have implemented QoS, are either incomplete or not setup
properly. They are having Voice Quality issues, such as, when someone
downloads a large file from the internet, from a remote site to the host
site, any calls going across those circuits get crushed and the quality
stinks. This, to me, is a sign that the QoS is not working properly.

I have recommended some traffic shaping policies, basically determining
how much bandwidth is needed for voice at each location, then putting a
policy in place that allows data (all but voice), to have X amount of
bandwidth on the circuits, and leaving the rest for Voice.

The big question that I have is:

How, with the Cisco IOS, would you handle the fact that a remote site
could be flooded with data? Meaning the aggregate of the bandwidth of
sites C,D, and E could flood site A. Is there a concept/technique that
addresses this possibility? I made some suggestions about redesigning
the network, and keeping all servers central, and minimizing data
traffic between remote sites. I have to think there is something in
Cisco’s QoS options that would address this, so Voice always has
priority and NEVER takes a hit.

I hope I explained this well enough. I appreciate any help. Please
yell at me if I am missing something important!

TIA,

Mike

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Hello Mike,

traffic-shaping, for voice, is not a good solution. You have to
implement LLC (Low Latency Queueing), so voice will be priority queued.
Additionally you have to make sure that your voice traffic is marked
with the right TOS/DSCP Parameters. For more information look at the
IOS configuration guides at CCO
(http://www.cisco.com/univercd/home/home.htm) They are listed under the
IOS Menue.

BNFH

bastardnetworkerfromhell wrote:
> Hello Mike,
>
> traffic-shaping, for voice, is not a good solution. You have to
> implement LLC (Low Latency Queueing), so voice will be priority queued.
> Additionally you have to make sure that your voice traffic is marked
> with the right TOS/DSCP Parameters. For more information look at the
> IOS configuration guides at CCO
> (http://www.cisco.com/univercd/home/home.htm) They are listed under the
> IOS Menue.
>
> BNFH
>

Thanks!

Anybody else?

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"Mike" <> wrote in message
news:...
> I need some guru help on this one.
>
> I am dealing with several Wide Area Networks which have or are
> implementing VoIP. Here is an example of a network:
>
> Host Site = 1.5MB
> Remote Site A = 512K
> Remote Site B = 768K
> Remote Site C = 512K
> Remote Site D = 768K
> Remote Site E = 960K
>
> These are private circuits all brought back to a VLAN on the carrier’s
> network (Layer 2).

this shows that there is some contention in the carrier network - if each
remote sends data to the centre, some packets are going to be dropped.

so - unless the carrier understands drop precedence so that your Voip
traffic gets through preferentially under congestion, you are going to have
voice quality issues.
>
> The ones that have implemented QoS, are either incomplete or not setup
> properly. They are having Voice Quality issues, such as, when someone
> downloads a large file from the internet, from a remote site to the host
> site, any calls going across those circuits get crushed and the quality
> stinks. This, to me, is a sign that the QoS is not working properly.

you need to check if this happens between sites as well. time for some
testing.....
>
> I have recommended some traffic shaping policies, basically determining
> how much bandwidth is needed for voice at each location, then putting a
> policy in place that allows data (all but voice), to have X amount of
> bandwidth on the circuits, and leaving the rest for Voice.
>
> The big question that I have is:
>
> How, with the Cisco IOS, would you handle the fact that a remote site
> could be flooded with data? Meaning the aggregate of the bandwidth of
> sites C,D, and E could flood site A. Is there a concept/technique that
> addresses this possibility?

there are 2 basic approaches.

1 limit the flow so that drops dont happen (i.e. limit the data rates from
the remote sites).
2 mark the traffic so that high priority stuff gets better treatment inside
the telco network.

I made some suggestions about redesigning
> the network, and keeping all servers central, and minimizing data
> traffic between remote sites. I have to think there is something in
> Cisco’s QoS options that would address this, so Voice always has
> priority and NEVER takes a hit.

cisoc QoS on your routers cant influence what happens elsewhere in the
network.
>
> I hope I explained this well enough. I appreciate any help. Please
> yell at me if I am missing something important!
>
> TIA,
>
> Mike
>
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Regards

Stephen Hope - return address needs fewer xxs