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Cisco routers and access servers run the industry-leading Cisco IOS software. This software ensures robust, reliable internetworks by supporting both LAN and WAN protocols, optimizing WAN services, and controlling internetwork access. In addition, Cisco IOS software allows centralized, integrated, and automated installation and management of all router and access server products.
This chapter contains the following sections:
Cisco IOS software is the platform that delivers network services and enables networked applications. Its software capabilities include those that are most fundamental for building networks and most robust for introducing new, leading-edge applications.
Connectivity, security, scalability, reliability, and management services are the foundation for all networks. Cisco IOS software seamlessly links disparate media and devices across the broadest set of protocols. It also protects corporate resources from intrusion by supporting comprehensive security features, including access control, authentication, and encryption. The most mission-critical operations can depend on Cisco IOS software to reliably deliver applications today and to scale to meet the increasing demands of tomorrow's network. Management services inherent in Cisco IOS software provide visibility that allows you to grow the network to keep up with rapidly changing business requirements.
As businesses rely on the network to deliver applications, the network must offer services to optimize these applications. Cisco IOS software provides network services, including IBM, voice, multimedia, and quality of service, which enable networked applications.
Cisco IOS software supports users and applications throughout the enterprise and provides security and data integrity for the internetwork. Cisco IOS software manages resources cost effectively by controlling and unifying complex, distributed network information. It also functions as a flexible vehicle for adding new services, features, and applications to the internetwork.
Cisco IOS software provides many internetwork benefits, which are described in the following sections:
Scalability provides the flexibility required to address all of the key issues facing internetworks as organizations evolve. Cisco IOS software uses scalable routing protocols to avoid needless congestion, overcome inherent protocol limitations, and bypass many of the obstacles that result from the complex scope and geographical dispersion of an internetwork.
Cisco IOS software reduces network costs by efficiently using network bandwidth and resources while eliminating the need for static routes. Advanced Cisco IOS features such as route filtering, protocol termination and translation, smart broadcasts, and helper address services combine to create a flexible, scalable infrastructure that can keep pace with evolving network requirements.
Cisco IOS software is reliable and adaptive because it identifies the best network paths and routes traffic around network failures.
Policy-based Cisco IOS features such as route filtering and route redistribution save network resources by preventing data from being unnecessarily broadcast to nodes that do not need it. Priority output queuing and custom queuing grant priority to important sessions when network bandwidth is scarce. Load balancing uses every available path across the internetwork to preserve valuable bandwidth and improve network performance. Cisco IOS software also provides the most effective and efficient scaling available for network applications that require transparent or source-route bridging algorithms.
Depending on the product you purchased, your Cisco device connects terminals, modems, microcomputers, and networks over serial lines to LANs or WANs. Cisco products provide network access to terminals, printers, workstations, and other networks.
On LANs, terminal services support TCP/IP on UNIX machines with Telnet and rlogin connections, IBM machines with TN3270 connections, and Digital machines with LAT connections. You can use the router or access server's protocol translation services to make connections between hosts and resources running different protocols including router and access server connections to X.25 machines using X.25 PAD.
Access servers provide remote configuration through Telnet and Digital Equipment Corporation's Maintenance Operation Protocol (MOP) connections to virtual ports.
Cisco IOS software supports four types of server operation:
Because most network costs are expended on WAN switching and bandwidth requirements, a cost-effective internetwork must optimize all WAN-related operations. Optimization increases network throughput while reducing delay time. It also reduces costs by eliminating unnecessary traffic and selecting the most economical WAN links available.
Cisco IOS software seamlessly accommodates circuit-switched WAN services such as Integrated Services Digital Network (ISDN), switched T1, and dial-up telephone lines. Cisco IOS software innovations such as dial-on-demand access and dial backup capabilities provide cost-effective alternatives to point-to-point switched leased lines. Support for advanced, packet-switched services such as X.25, Frame Relay, Switched Multimegabit Data Service (SMDS), and ATM extends the internetwork across the broad range of WAN interface alternatives now available.
In addition to remote node WAN connectivity with ARA, SLIP, PPP, or XRemote, other WAN services include dial-on-demand routing (DDR) of IP and IPX, X.25, Frame Relay, and SMDS.
Cisco IOS software provides an array of network management and security capabilities designed to meet the needs of today's large, complex internetworks. Integrated management simplifies administrative procedures and shortens the time required to diagnose and fix problems. Automated operations reduce hands-on tasks and make it possible to manage large, geographically dispersed internetworks with a small staff of experts located at a central site.
Cisco IOS software provides several important management features that are built into every Cisco router and access server. These management features include configuration services, which lower the cost of installing, upgrading, and reconfiguring routers and access servers, as well as comprehensive monitoring and diagnostic services. In addition, Cisco IOS software provides valuable information and services for router management applications developed by Cisco and its partners. Cisco applications, known collectively as CiscoWorks, offer administrators a wide-ranging suite of operational, design, and management capabilities that increase productivity and reduce costs.
Cisco IOS management services are matched by their security capabilities. Cisco IOS software includes a diverse tool kit for partitioning resources and prohibiting access to sensitive or confidential information and processes. Multidimensional filters prevent users from knowing that other users or resources are even on the network. Encrypted passwords, dial-in authentication, multilevel configuration permissions, and accounting and logging features provide protection from--and information about--unauthorized access attempts.
This section describes how Cisco IOS software is packaged and helps you determine which Cisco IOS software features apply to the various Cisco hardware platforms offered. It also describes the feature set packaging available with Cisco IOS Release 11.2 and later releases.
This catalog introduces a new software product, Cisco IOS software feature packs. A software feature pack consists of a CD-ROM that contains software images and a Windows 95 application, which loads the images onto a router. Software feature packs are available only for Cisco IOS Release 11.2. Each Cisco IOS Release 11.2 feature pack CD contains one or more feature sets and, for the Cisco AS5200 feature packs, modem software. If you don't have Windows 95, you can load the images with Windows 3.1 and a TFTP server application.
Cisco IOS feature packs are primarily used as a means of software distribution by resellers, who load their customers' selection of router software at the resellers' sites. However, you can use feature packs in any situation that requires an alternative to standard software distribution (that is, factory installation of software, diskettes, Flash memory cards, or Cisco Connection Online download).
Each Cisco IOS Release 11.2 software feature pack box contains the following items:
With the introduction of Cisco IOS Release 11.2, feature sets were updated to make it easier to select the exact feature sets you need. Feature set names were simplified and made more consistent across Cisco hardware platforms. In addition, you can add options to the standard feature set offerings. These options provide additional features and value based on the hardware platform selected. Cisco also continues to offer specialized feature sets for key applications.
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