Typical Small Site Traditional Data Network
Internet
Router
3524 Switch
Network
Printer
Server
Server
Typical Small Site Telephone Network
Public Branch
Exchange (PBX)
Telecomm
Office PBX
Connection to
the Carrier
OfficeJet Fax
Traditional Telephones
Therefore, in order for this typical small site system to accommodate VoIP
and AVVID solutions, these two systems must first be merged onto a suitable network
infrastructure.Today’s typical data network uses category-5 twisted pair
cabling as a minimum, which easily supports voice and data networking.While
this is a good start, the LAN must also support moves, adds, and changes for
Ethernet connectivity on a very easy-to-maintain network infrastructure.This
means that for a period of time, the two systems will remain apart and operate as
parallel systems just like they did before all of this first started.
As the merger of the two systems begins, there is a distinct order to the
migration, as stated in the following:
1. Connect the new AVVID-capable system to the external telco provider.
2. Install and configure supporting VoIP and AVVID systems onto the
updated network.
3. Begin replacing the standard analog telephone devices with the new
VoIP devices, usually one at a time to ensure a smooth transition.
Though these seem like three short steps, it might take two weeks to complete
them for 30 users. One of the most important aspects of small site VoIP solutions is
to make certain the proper hardware is used the first time around so this critical
capital expense is done only once.Having the proper LAN hardware also ensures
that the installation and migration goes as smoothly as possible.When this migration
completes, the new VoIP system will look something like Figure 10.3.
The forthcoming sections will help you understand how to perform this
migration, and how to create your very own new VoIP-capable network. For
now, you must understand that in Figure 10.3, the solid lines are for the data
VLAN, the dashed lines for the Voice VLAN, and also realize that the router performs
routing between the VLANs when necessary.This configuration makes certain
that data packets do not interfere with voice packets, and ensures the proper
quality of service in the networking devices required to maintain the proper
voice quality.This small site solution was accomplished by deploying the following
Cisco equipment:
A Model 2621 router with 16MB of flash memory, Cisco IOS version
12.1(5)T8, 48MB of memory for the operating system and shared
buffers.The IOS you use will probably differ from this due to your own
requirements.
One Primary Rate Interface (PRI) module for the telco central office
connection.
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One Model 3524 In-line power Ethernet switch to provide power for
the Cisco Model 7960 IP phones.
Cisco Model 7960 IP phones, which support multiple lines, speed
dialing, conferencing, and multiple feature support.This phone is actually
a two-port Ethernet switch that provides 10/100 Mbps Ethernet connectivity
for the desktop computer, as well as connectivity to the 3524
In-line power switch.
A Cisco CallManager Server, which provides the core PBX functionality.
A Cisco Unity Messaging Server, which provides voice mail capabilities
interconnected via Microsoft Exchange Server v5.5 for voice/messaging
interaction.