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A similar approach assesses the availability in Cleveland, and is shown in
System Availability in
Table 58: Weighted System Availability in Cleveland
Full Solution Availability Projected
% of traffic generated in Atlanta
downtime minutes in Atlanta
% of traffic generated in Boston
downtime minutes in Boston
% of traffic between Atlanta and Boston
Annual downtime minutes due to failure in
Atlanta, WAN, and in Boston
% of traffic generated in Cleveland
Annual downtime minutes in Cleveland
% of traffic between Atlanta and Cleveland
Annual downtime minutes due to failure
in Atlanta, WAN, and in Cleveland
% of traffic between Boston and Cleveland
Annual downtime minutes due to failure
in Boston, WAN, and in Cleveland
Aggregated Downtime
System Availability = 99.5%
As reflected in
bottleneck in this configuration is the single WAN link supporting the call control signaling
between the headquarters and either of the branch offices. Case Study II demonstrates the
effect of a LSP on improving the local availability for the branch offices.
Case Study II (99.6% Availability)
In this configuration, the call processing signaling traffic has higher availability value in the
Cleveland office. In addition, Atlanta IP traffic is enhanced by implementation of N+1 IP
resources.
The LSP in Cleveland is the alternate gatekeeper and call controller for the IP phones and
the G700 Media Gateways located in the Cleveland site.
N+1 IPSI, C-LAN and Media Processor circuit packs in Atlanta. This is done by distributing
the call control link to the port networks (the G650 media gateways) over two IP links,
supported by two IPSI circuit packs, and increasing the number of C-LAN circuit packs by
one. Such distribution of resources allows for IP phone service availability in the event of a
link or device failure.
Cleveland.
Table 58: Weighted System Availability in
Weighted Downtime minutes.
Annual
(43.3% + 14.2%)
Annual
(16% + 2%)
(5.2% + 5.2%)
(7% + 0.4%)
(2.7% + 2.2%)
(0.9% + 0.9%)
2388 minutes
(151 + 947 + 547 + 390 + 258 + 95)
Cleveland, the main availability
Design for High Availability
Table 58: Weighted
263 = 151
5260 = 947
5260 = 547
5260 = 390
5260 = 258
5260 = 95
Issue 3.4.1 June 2005
265
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