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Lesson 3Design Decisions for a Proxy Server Solution
ObjectiveExplain factors that determine the appropriateness of Proxy Server Solution

Design Decisions for a Proxy Server Solution

When using Proxy Server, your design decisions for an internet-connectivity solution must be based on the security requirements, the network configuration, the number of Internet-exposed resources, and the number of geographically distributed locations for the organization. Proxy Server is an appropriate solution for Internet connectivity if:
  1. Internet and private network access is restricted on a user-by-user basis or on a resource-by-resource basis
  2. The private network is in a routed or non-routed environment
  3. A number of private network resources need to be shared with Internet-based users
  4. The private network encompasses multiple geographic locations
Question: Proxy Server is an appropriate solution only if the private network is in a routed environment (True or False?).
Anwser: False. The private network may be in either a routed or non-routed environment.
In the next lesson, you will learn the benefits of integrating Proxy Server with other networking services.


Proxy Server Design Requirements and Constraints

Before you create your Proxy Server design, you must gather the requirements and constraints, both business and technical, of the organization. As you create your design, you make design decisions based on the requirements and constraints that you collect. The list of the design requirements and constraints that you collect includes
  1. Characteristics of the data transmitted through the proxy server, including
    1. The amount of data transmitted through the proxy server
    2. The confidentiality of the data transmitted through the proxy server
  2. Resources in the private network that must be accessed by Internet-based users
  3. Plans for future network growth
  4. Characteristics of existing proxy server including
    1. Protocols in use in the private network
    2. Proxy server placement
    3. Wide area network (WAN) connections in use
    4. Response times for applications that access resources through the proxy server(s)
  5. Acceptable percentage of time that users require access through the proxy server(s)

Proxy Server Design Decisions

After you determine the business and technical requirements and constraints, apply the information you gathered to make Proxy Server design decisions. To create your Proxy Server design, you must choose the
  1. Types of connections, persistent or nonpersistent, that each proxy server must support
  2. Types of Proxy Server clients that must be supported by each proxy server
  3. Connection technologies, including T1, Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN), Digital Subscriber Line (DSL), or X.25, that each proxy server must support
  4. Dynamic routing protocols or manual routing table entries that each router must support
  5. Multiple connections and multiple proxy servers to improve availability and performance
  6. Criteria that you will adopt to filter traffic
The lessons that follow in this chapter provide the information required for you to make specific Proxy Server design recommendations.

Internet Connectivity Designs

The most common solution that you will provide in your designs is found in Internet connectivity designs. In Internet connectivity designs, you connect private networks to the Internet. Your primary concern in Internet connectivity designs is to provide Internet access for private network users and to give private network resources access to Internet users. Typically, in Internet connectivity designs, the proxy server takes the place of a firewall. As a result, security is one of your primary concerns in Internet connectivity designs.