Since the inception of packet-based communications, networks have always offered a forwarding service. Forwarding is the fundamental activity within an internetwork. In IP, this forwarding service was built on the assumption that end nodes in the network were intelligent, and that the network core did not have intelligence. With advances in networking software and hardware, the network can offer an increasingly rich, intelligent set of mechanisms for forwarding information. Interactive services add intelligence to the network infrastructure, beyond simply moving a datagram between two points.
For example, through intelligent network classification, the network distinguishes and identifies traffic based on application content and context. Advanced network services use the traffic classification to regulate performance, ensure security, facilitate delivery, and improve manageability.
Network applications such as IP telephony support the entire enterprise network environment— from the teleworker to the campus to the data center. These applications are enabled by critical network services and provide a common set of capabilities to support the application's networkwide requirements, including security, high availability, reliability, flexibility, responsiveness, and compliancy.
Recall the layers of the Cisco SONA framework, illustrated in Figure 3-14. The SONA interactive services layer includes both application networking services and infrastructure services.
Figure 3-14 Cisco SONA Framework
Places in the Network
For example, the following infrastructure services (shown earlier in Figure 3-8) enhance classic network functions to support today's applications environments by mapping the application's requirements to the resources that they require from the network:
■ Security services: Ensure that all aspects of the network are secure, from devices connecting to the network to secured transport to data theft prevention
■ Mobility services: Allow users to access network resources regardless of their physical location
■ Storage services: Provide distributed and virtual storage across the infrastructure
■ Voice and collaboration services: Deliver the foundation by which voice can be carried across the network, such as security and high availability
■ Compute services: Connect and virtualize compute resources based on the application
■ Identity services: Map resources and policies to the user and device
Examples of network services imbedded in the infrastructure services include the following:
■ Network management: Includes LAN management for advanced management of multilayer switches; routed WAN management for monitoring, traffic management, and access control to administer the routed infrastructure of multiservice networks; service management for managing and monitoring service level agreements (SLAs); and VPN security management for optimizing VPN performance and security administration.
■ High availability: Ensures end-to-end availability for services, clients, and sessions. Implementation includes reliable, fault-tolerant network devices to automatically identify and overcome failures, and resilient network technologies.
■ QoS: Manages the delay, delay variation (jitter), bandwidth availability, and packet loss parameters of a network to meet the diverse needs of voice, video, and data applications. QoS features provide value-added functionality, such as network-based application recognition for classifying traffic on an application basis, Cisco IOS IP SLAs (previously called the service assurance agent) for end-to-end QoS measurements, Resource Reservation Protocol signaling for admission control and reservation of resources, and a variety of configurable queue insertion and servicing functions.
■ IP multicasting: Provides bandwidth-conserving technology that reduces network traffic by delivering a single stream of information intended for many recipients through the transport network. Multicasting enables distribution of videoconferencing, corporate communications, distance learning, software, and other applications. Multicast packets are replicated only as necessary by Cisco routers enabled with Protocol Independent Multicast and other supporting multicast protocols that result in the most efficient delivery of data to multiple receivers.
To support network applications efficiently, deploy the underlying infrastructure services in some or all modules of the enterprise network as required. These design elements can be replicated simply to other enterprise network modules as the network changes. As a result, modularization to small subsets of the overall network simplifies the network design and often reduces the network's cost and complexity.
The following sections explore some of the infrastructure services and application networking services. Network management services are described in the "Network Management Protocols and Features" section later in this chapter.
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