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
>
>