Does the Customer Need Clustering?
Your next task is to decide whether or not clustering is required, and what
should be the configuration of these clusters.The first step in this process is to
total up the number of IP phones required, as well as the total device weight of
IP telephony devices on the network.
There are 2,000 IP phones on the headquarters campus, and 40 IP phones at
each of the 20 remote sites. Using the formula, that tabulates as 2,000 + (20 x
40) = 2,800 IP phones.
Device weights are as follows:
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122 Chapter 4 • AVVID Clustering
2,800 phones @ 1 unit each = 2,800 units
1,400 voice mail accounts @ 3 units each = 4,200 units
50 analog gateways @ 3 units each = 150 units
2 T1 gateways @ 72 units each = 144 units
22 MCUs @ 45 units each = 990 units
This gives a grand total of 8,284 device units.
A single CallManager server will support up to 2,500 IP phones, and you
require 2,800, so you can immediately see that you need to use clustering. Even
if this were not the case, a single CallManager server can only support 5,000
device units, and you require 8,284. In addition, you require clustering to facilitate
the customer’s reliability requirements.