Objective Area #2: Implementation & Operations

This area covers the following topics:

• Configure routing protocols given user requirements.
• Configure IP addresses, subnet masks, and gateway addresses on routers and hosts.
• Configure a router for additional administrative functionality.
• Configure a switch with VLANS and inter-switch communication.
• Implement a LAN.
• Customize a switch configuration to meet specified network requirements.
• Manage system image and device configuration files.
• Perform an initial configuration on a router.
• Perform an initial configuration on a switch.
• Implement access lists.
• Implement simple WAN protocols.

Routers can be configured for network routes and discovery via routing protocols. Manually configured, connected and static routes are usually preferred since they have some of the lowest administrative distances. For the exam, remember when viewing the routing table of a Cisco router, you will see two values in brackets -- such as [100/2] -- which indicates the administrative distance and hop count or other metric. Also indicated next to each route in the table is whether it is a connected route (C), static route (S), or was learned dynamically via a routing protocol (with designations such as R for RIP and I for IGRP).

RIP and IGRP are fairly simple to configure. For RIP the IOS command would be router rip followed by the network statement. For IGRP it is router igrp 10, which includes an autonomous system number, followed by a network statement.

Tip: When an interface is configured for passive routing, the interface will accept but not advertise network routes.

Once again, this section of the exam relies heavily on your knowledge of subnetting. You may be presented with a simple network diagram consisting of subnets, routers and hosts, and be asked to identify the proper assignment of IP addresses. Read each and every address carefully as the answer may not always be obvious!

Every CCNA should understand what happens within a Cisco switch and the bridging functions of a network. You'll want to be familiar with STP (Spanning Tree Protocol), VLANs, and the switching methods cut-through and store-and-forward. Cut-through switching is a preferred method when media collisions are low and latency at the switch cannot be tolerated. Store-and-forward, on the other hand, is needed when media collisions are high and a higher latency is acceptable.

VLANs have become a popular implementation method to connect network clients and their preferred servers logically, through the switched networks, without having to connect them to the same physical switch. The network administrator generally configures vLANs within the switches. They offer levels of security and control plus limit network broadcast traffic, much like routers.

Referring back to the Cisco white paper mentioned earlier (link above), using extended access lists you can deny telnet traffic to a router's interface; for example, ip access-list 101 deny tcp any any eq telnet (don't forget to also add a permit statement such as ip access-list 101 permit ip any any or all traffic will be denied). You would then apply the access list to the filtered interface: ip access-group 101 in.

There are many things to configure to prepare an interface for a frame relay connection, and you should be intimately familiar with all of them. Memorize the different frame relay, DLCI configurations and LMI types. Frame relay encapsulation types are cisco and ietf with cisco being the default. DLCIs are locally significant and only represent the connection identifier from the router to the frame switch. LMI types are ansi, cisco and q933a. When there is a mismatch between two routers, communication will not take place.

ISDN and DDR configuration is new to the CCNA list of topics--not ISDN as a protocol, but as a complete understanding of how to configure ISDN and dial-on-demand routing (DDR). To begin with, here is a great reference for study: http://www.cisco.com/warp/public/793/access_dial/ddr_dialer_profile.html.

Be sure you understand the components and commands of a dialer profile and the order of configuration: