Performing Advanced Configuration Tasks
Let’s do a quick review of what we’ve accomplished thus far, so we can be clear
about what’s left to do:
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A Word about Regions and Device Pools
In the system configuration of CCM, you have to create device pools and
regions that deal with how the phone call is treated. These two conditions
do more for quality of service than any other configuration. There
are two basic types of compression and voice handling: g.711, which
uses the full 64 Kbps PRI channel when high bandwidth is available, and
g.729, which compresses the voice packet down to 8 Kbps for transmission
across low speed WAN links such as 56 Kbps frame relay. There are,
however, several other compression types, some that go as low as 5.3
Kbps, but that require more advanced (and more expensive) DSP modules.
When these high-complexity DSPs are employed, you’ll need to use
gateways such as the Cisco 3600 and AS5000 Series devices.
Where and when would you need such high level hardware,
though? The previously mentioned 1750 and 2600 class gateways using
the voice modules can provide adequate voice compression and mixing
for up to four conversations, but fall short when more than four simultaneous
conversations are needed. The 3640 gateway, for instance, can
accept up to 12 DSP modules that each have three individual DSP processors,
with each DSP processor handling one conversation. Also, when
conference calls and bridging are needed, one DSP processor is required
for every three participants in the call. DSP processors can be co joined
for larger conferencing needs, but require the usage of more capable
gateways such as the Catalyst line of switches. These Model 4000 and
Model 6000 Series Catalyst switches utilize the 8-port T-1 DSP module,
with each module supporting three individual DSP processors. However,
these 24 combined processors provide much more VoIP capabilities than
do the lower end gateways.
This diatribe is not meant to say that the 1750 and 2600 class gateways
are not sufficient to do the job—far from it. They each have their
particular place in life as well as an associated cost. Chapter 11 will go
into these more advanced issues in greater detail.
Configuring & Implementing…
362 Chapter 10 • Designing and Implementing Single Site Solutions
1. Installed CCM server.
2. Created or updated DHCP and DNS to support CCM and the phones.
3. Performed physical installation of the phones.
4. Verified phones start up correctly.
Next, we’re going to perform the advanced tasks needed to make the phone
fully operational. Please note that this will not be a step-by-step configuration
since your needs may vary. Instead, the functional areas will be presented and
discussed.
First on the list is to create what can be called regions in CCM.A region is an
area of phones overseen by CCM, which tells them how they should communicate
with phones outside their region.With phones located on the local network, using
g.711 compression (or lack thereof) allows the phone to have the highest quality of
voice with the least demanding processing requirements. Since the 3524 switch is
Fast Ethernet capacity, using g.711 on the local network makes the best sense.To
designate a region, go to the System menu on the CCM Administration screen
and choose Region (see Figure 10.12).