Page 264 - Using MIS

232 Chapter 6 The Cloud

Chicago Site

Local Area
Network 1

Remote
Client
Figure 6-21
Remote Access Using VPN;
Apparent Connection

In either case, once the Internet connection is made, VPN software on the remote user’s
computer establishes a connection with the VPN server in Chicago. The VPN client and VPN
server then have a secure connection. That connection, called a tunnel, is a virtual, private
pathway over a public or shared network from the VPN client to the VPN server. Figure 6-21 il-
lustrates the connection as it appears to the remote user.
To secure VPN communications over the public Internet, the VPN client software encrypts,
or codes (see Chapter 10, page 385), messages so their contents are protected from snooping.
Then the VPN client appends the Internet address of the VPN server to the message and sends
that package over the Internet to the VPN server. When the VPN server receives the message, it
strips its address off the front of the message, decrypts the coded message, and sends the plain
text message to the original address inside the LAN. In this way, secure private messages are
delivered over the public Internet.

Using a Private Cloud

A private cloud is a cloud that is owned and operated by an organization for its own benefit.
To create a private cloud, the organization creates a private internet and designs applications
using Web services standards just as shown in Figure 6-19 (page 229). The organization then
creates a farm of servers and manages those servers with elastic load balancing just as the
cloud service vendors do. Because of the complexity of managing multiple database serv-
ers, most organizations choose not to replicate database servers. Figure 6-22 illustrates this
possibility.

Private Cloud
Browsers in
Browsers in
Browsers
Sales Dept in
Browsers
Sales Dept in
Browsers
Sales Dept in
Browsers
Sales Dept in
Sales Dept Browsers in
Browsers in
Sales Dept Browsers in
Browsers
Sales Customer in
Customer
Browsers in
Elastic Load Service
Customer
Customer
Balancer Service
Inventory Service
Application Inventory Service
service requests Application
& responses
Inventory & Other service requests
Applications & responses
Web servers
Database server Browsers in
Browsers in
Browsers in service requests & Accounting
Browsers in
Browsers in responses Accounting
Browsers
Shipping in Accounting
Shipping in
Browsers
Shipping in
Browsers
Shipping DBMS DB
Shipping
Database Server
Figure 6-22
Private Cloud for Inventory and
Other Applications