Enterprise Composite Network Model

The newer Cisco model—the Enterprise Composite Model—is significantly more complex and attempts to address the major shortcoming of the Hierarchical Design Model by expanding the older version and making specific recommendations about how and where certain network functions should be implemented. This model is based on the principles described in the Cisco Architecture for Voice, Video, and Integrated Data (AVVID).

The Enterprise Composite Model is broken up into three large sections:

■ Enterprise Campus—The portion of the design that is like the old hiearchical model.

■ Enterprise Edge—The connections to the public network.

■ Service Provider Edge—The different public networks that are attached.

The first section, the Enterprise Campus, looks like the old Hierarchical model with some added details. The Enterprise Campus is shown in Figure 1-2. It features six sections:

■ Campus Backbone—The center of the network, like the old "core".

■ Building Distribution—Intermediate devices that route from the core to access devices.

n Building Access—Connections for end systems. n Management—Command, control, and auditing features. n Edge Distribution—A distribution layer out to the WAN. n Server Farm—For Enterprise services.

The Enterprise Edge (shown in Figure 1-3) details the connections from the campus to the Wide Area Network and includes:

■ E-Commerce—Externally accessible services that have ties to internal data stores.

■ Internet Connectivity—Connectivity to outside services.

FIGURE 1-2 THE ENTERPRISE CAMPUS

FIGURE 1-2 THE ENTERPRISE CAMPUS

THE EVOLVING NETWORK MODEL

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FIGURE 1-3 THE ENTERPRISE EDGE

FIGURE 1-3 THE ENTERPRISE EDGE

Enterprise Edge

Service Provider Edge

THE EVOLVING NETWORK MODEL

THE EVOLVING NETWORK MODEL

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The Service Provider Edge consists of the public networks that facilitate wide-area network connectivity:

■ Internet Service Provider (ISP)—Public connectivity

■ Public Switched Telephone Network (PSTN)—Dial up

■ Frame Relay, ATM, and PPP—Private connectivity

Figure 1-4 puts together the various pieces: Campus, Enterprise Edge, and Service Provider Edge. Security implemented on this model is described in the Cisco SAFE (Security Architecture for Enterprise) blueprint.

FIGURE 1-4 THE COMPLETE ENTERPRISE COMPOSITE MODEL

FIGURE 1-4 THE COMPLETE ENTERPRISE COMPOSITE MODEL

Enterprise Campus

Enterprise Edge

Service Provider Edae

Enterprise Campus

Enterprise Edge

Service Provider Edae

SONA and IIN

Modern converged networks include different traffic types, each with unique requirements for security, QoS, transmission capacity, and delay. These include:

■ Voice signaling and bearer

■ Core Application traffic, such as Enterprise Resource Programming (ERP) or Customer Relationship Management (CRM)

■ Database Transactions

■ Multicast multimedia

■ Network management

■ "Other" traffic, such as web pages, e-mail, and file transfer

Cisco routers are able to implement filtering, compression, prioritization, and policing (dedicating network capacity). Except for filtering, these capabilities are referred to collectively as QoS.

Note

The best way to meet capacity requirements is to have twice as much bandwidth as needed. Financial reality, however, usually requires QoS instead.

Although QoS is wonderful, it is not the only way to address bandwidth shortage. Cisco espouses an ideal called the Intelligent Information Network (IIN).

IIN describes an evolutionary vision of a network that integrates network and application functionality cooperatively and allows the network to be smart about how it handles traffic to minimize the footprint of applications. IIN is built on top of the Enterprise Composite Model and describes structures overlaid on to the Composite design as needed in three phases.

Phase 1, "Integrated Transport," describes a converged network, which is built along the lines of the Composite model and based on open standards. This is the phase that the industry has been transitioning to for the last few years, and the Cisco Integrated Services Routers (ISR) are an example of this trend.

Phase 2, "Integrated Services," attempts to virtualize resources, such as servers, storage, and network access and move to an "on-demand" model.

By "virtualize" Cisco means that the services are not associated with a particular device or location. Instead, many services can reside in one device to ease management, or many devices can provide one service that is more reliable.

An ISR brings together routing, switching, voice, security, and wireless. It is an example of many services existing on one device. A load balancer, which makes many servers look like one, is a second example.

VRFs are an example of taking one resource and making it look like many. Some versions of IOS are capable of having a router present itself as many virtual router forwarding (VRF) instances, allowing your company to deliver different logical topologies on the same physical infrastructure. Server virtualization is another example. The classic example of taking one resource and making it appear to be many resources is the use of a virtual LAN (VLAN) and a virtual storage area network (VSAN).

Virtualization provides flexibility in configuration and management.

Phase 3, "Integrated Applications," uses application-oriented networking (AON) to make the network application-aware and to allow the network to actively participate in service delivery.

An example of this phase 3 IIN systems approach to service delivery is Network Admission Control (NAC). Before NAC, authentication, VLAN assignment, and anti-virus updates were separately managed. With NAC in place, the network is able to check the policy stance of a client and admit, deny, or remediate based on policies.

IIN allows the network to deconstruct packets, parse fields, and take actions based on the values it finds. An ISR equipped with an AON blade might be configured to route traffic from a business partner. The AON blade can examine traffic, recognize the application, and rebuild XML files in memory. Corrupted XML fields might represent an attack (called schema poisoning), so the AON blade could react by blocking that source from further communication. In this example, routing, an awareness of the application data flow, and security are combined to allow the network to contribute to the success of the application.

Services-Oriented Network Architecture (SONA) applies the IIN ideals to Enterprise networks. Figure 1-5 shows how SONA breaks down the IIN functions into three layers:

■ Network Infrastructure—Hierarchical converged network and attached end systems.

■ Interactive Services—Resources allocated to applications.

■ Applications—Includes business policy and logic.

FIGURE 1-5 IIN AND SONA COMPARED

THE EVOLVING NETWORK MODEL

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FIGURE 1-5 IIN AND SONA COMPARED

IIN Phases

SONA Framework Layers

Business Apps

Middleware

Collaboration Apps

Middleware

Application Networking Services

Infrastructure Services

Network

Clients

Vlan

Continue reading here: Hot Standby Router Protocol HSRP

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