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Accessible but Secure Access-layer routers must both be accessed and be used to connect to a variety of WAN services, while maintaining security to keep hackers out. com Fault-Tolerant Topologies 15 The following Cisco IOS features support these requirements: Dedicated and switched WAN support You can create a direct connection with Cisco routers using basic or digital services (a T1, for example). 25, and ATM to give you options to meet cost, location, and traffic requirements. Exterior protocol support Both Exterior Gateway Protocol (EGP) and Border Gateway Protocol (BGP) are supported by the Cisco IOS.

When used properly in network design, it makes networks more predictable. It helps us to define and expect at which levels of hierarchy we should perform certain functions. You would ask your boss, not your subordinate, for a raise because of their relative positions in the business hierarchy. That is what the hierarchy defines. Likewise, you can use tools such as access lists at certain levels in hierarchical networks and avoid them at others. Let’s face it: large networks can be extremely complicated, with multiple protocols, detailed configurations, and diverse technologies.

2 5 An expanded hierarchical network Main Office Regional Offices Sales Offices Manageability Hierarchical networks are easier to manage than other types of networks because they are easier to troubleshoot. For example, anyone familiar with Ethernet will know what great fun it is to troubleshoot 10Base2 (a coaxnetwork infamous for poor troubleshooting avenues). If the network is down, where do you begin (assuming you lack sophisticated diagnostic tools)? You’ll need more cable when installing 10BaseT, but the cost is almost always justified because troubleshooting a star network is so much easier than troubleshooting a bus network.