- Understanding the Model
- Identifying Key Components
- Applying Architectural Principles
- Applying the Model to FijiNet
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Identifying Key Components
After analyzing business and functional requirements (see Chapter 2), the initial step in modeling an ISP architecture is to identify key components.
In general, key components are uniform among most designs; at the minimum, there should be ISP services running within an operating environment on an operating platform. As shown in FIGURE 1, the core of this model consists of ISP services, operating environment, and operating platform.
TIP
The differences in a design are typically in the selection of services, an operating environment, and the operating platform, all of which are based on business requirements and preferences.
ISP Services
ISP services are usually categorized into four types: basic services, value-added services, infrastructure services, and operation and management services. The following paragraphs describe each of these.
Basic Services
Basic services are common services offered by ISPs to residential and business subscribers. As shown in FIGURE 2, basic services are email, web hosting, and Internet news. Although not listed, Internet access and FTP (file transfer protocol) are considered basic services; they are required for connectivity and content uploads, respectively.
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FIGURE 2 Basic Services
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Internet News |
Post news on the Internet |
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Web Hosting |
Host personal web pages |
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Send and receive email |
Value-Added Services
Value-added services are special services offered to provide additional value to existing subscribers, to attract new subscribers, and to differentiate services from those offered by competitors. FIGURE 3 shows a sample of value-added services an ISP might offer.
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FIGURE 3 Value-Added Services
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Calendar |
Schedule appointments |
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Search Engine |
Online search capabilities |
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WebMail |
Email via web browser |
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IR Chat |
Internet relay chat (IRC) |
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Short Messaging Service |
Send text messages via short messaging service (SMS) |
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Address Book |
Personal address book |
What constitutes value-added services varies among ISPs and changes quickly as competitors follow leaders. Samples of value-added services are calendar, search engine, WebMail, IRC, SMS, and address book.
To add value, these services enhance a user's experience and provide tools that users want conveniently at their fingertips. Large ISPs today are aiming to be one-stop portals for everything from web surfing to online shopping.
As new services become more common, many ISPs subsequently convert value-added services to basic services.
Infrastructure Services
Infrastructure services are services that are absolutely critical to support other ISP services running within an infrastructure. These services run in the background and are transparent to users. Infrastructure services are the workhorses of infrastructure functions. FIGURE 4 shows the minimum required infrastructure services.
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FIGURE 4 Infrastructure Services
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DNS |
Domain name system is for name resolution. |
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LDAP |
Lightweight directory access protocol (LDAP) is for authentication and authorization. |
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RADIUS |
Remote access dial-in user service (RADIUS) is for remote access authentication. |
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NTP |
Network time protocol (NTP) is for time synchronization. |
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DHCP |
Dynamic host configuration protocol (DHCP) is for dynamic host configurations for client systems. |
Operation and Management Services
Operation and management services are services that allow system administrators to maintain an environment and provide business continuity through uptime. These services are critical to the operation and management of an ISP. Routine tasks such as performing nightly backups, changing tapes, restarting services, installing software patches and upgrades, and monitoring ensure that the environment is working well.
FIGURE 5 shows operation and management services. Although these services are technically a form of infrastructure services and play a support role within an infrastructure, one or more of these services might not be an absolute requirement, depending upon an ISP's business requirements.
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FIGURE 5 Operation and Management Services
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JumpStart |
Automates system installation and management tasks. |
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Monitoring |
Monitors system utilization, intrusions, service availability, etc. |
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Provisioning |
The two categories of provisioning are user and services. User provisioning consists of new user registration, care, and billing. Service provisioning consists of installing new software, patch updates, and software upgrades. |
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Back Up |
Nightly backup for data protection and disaster recovery. |
Operating Environment
An operating environment (OE) consists of an operating system (OS) and bundled tools and applications to provide a total solution with seamless integration. Most vendors offer a wide selection of packages for their OS, with different tools and applications.
NOTE
Most Internet tools are developed in UNIX_ before they are ported to other platforms, which may be a consideration when choosing an OE.
Most vendors include applications with an OE. These applications can be commercial, open source, or a combination of both. Commercial applications are usually high-end applications for enterprise environments, and licensing for these applications varies among vendors. Open source applications are usually lower-end applications with limited functionality and features, and licensing agreements are commonly provided under general public license (GPL).
Operating Platform
An operating platform is the underlying hardware platform that supports the operating environment. This hardware includes network equipment, enterprise servers, storage, etc.