Sunday, May 2, 2010

Router user interface

Router user interface
2.1.2 This page will review the Cisco IOS. The IOS is a core technology that extends across most of the Cisco product line. Its operation details may vary on different internetworking devices.


The CLI environment can be accessed several ways. Typically, the CLI is accessed through a console session. A console uses a low speed serial connection directly from a computer or terminal to the console connection on the router. A CLI session can also be accessed remotely through a dialup connection using a modem connected to the router AUX port. Neither of these methods require that the router have any IP services configured. A third method of accessing a CLI session is to Telnet to the router. To establish a Telnet session to the router, at least one interface must be configured with an IP address, and virtual terminal sessions must be configured for login and passwords.

The next page discusses the different user modes that are available for Cisco IOS.

Module 2: Introduction to Routers / Overview / The purpose of Cisco IOS software

Module 2: Introduction to Routers
Overview: Cisco technology is based on the Cisco IOS, which is the software that controls the routing and switching functions of network devices. A solid understanding of the IOS is essential for a network administrator. This module will introduce the main features of the IOS and will provide practice in working with the IOS. All network configuration tasks, from the most basic to the most complex, require a strong foundation in the basics of router configuration. This module will provide the tools and techniques for basic router configuration that will be used throughout this course.


This module covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND 640-811 exams. -

Students who complete this module should be able to perform the following tasks:

• Describe the purpose of the IOS
• Describe the basic operation of the IOS
• Identify various IOS features
• Identify the methods to establish a command-line interface (CLI) session with the router
• Alternate between the user executive (EXEC) and privileged EXEC modes
• Establish a HyperTerminal session on a router
• Log into a router
• Use the help feature in the command line interface
• Troubleshoot command errors

The purpose of Cisco IOS software 
2.1.1 As with a computer, a router or switch cannot function without an operating system. This page will review the Cisco IOS. It is the embedded software architecture in all of the Cisco routers and is also the operating system of the Catalyst switches. Without an operating system, the hardware does not have any capabilities. The Cisco IOS provides the following network services:


• Basic routing and switching functions
• Reliable and secure access to networked resources
• Network scalability

The next page will discuss the Cisco IOS environment for a router.

Saturday, April 24, 2010

Summary of Module 1 Semester 2

Summary
This page summarizes the topics discussed in this module.


The major difference between a WAN and a LAN is the geographical area that is covered. A LAN connects workstations, printers, servers, and other devices within a building or other small area. A WAN is used to connect multiple LANs, typically over a large geographical area. The primary characteristics of a WAN include the ability to connect devices separated by wide geographical areas, the use of service companies to make these connections, and the serial connections used to access bandwidth.

There are several organizations that define and manage the standards used for WAN design such as ITU-T, ISO, IETF, and EIA.

WANs operate at the physical layer and the data link layer, which are Layers 1 and 2 of the OSI reference model. The devices used in a WAN, such as routers, CSU/DSUs, modems, and communication servers, operate at the physical layer. At the data link layer, the protocols determine how frames are carried between systems. A router can act as a LAN or a WAN device because it operates at the network layer, which is Layer 3.

Routers are specialized computers that use the Cisco IOS software to run configuration files. The main internal components of a router are as follows:

• The CPU, which executes instructions in the operating system
• RAM or DRAM to store the routing tables
• NVRAM to provide storage for the startup configuration file
• Flash memory to hold the IOS
• ROM for the POST
• Interfaces to connect to a PC or modem

There are three basic external connections on a router:
• LAN interface
• WAN interface
• Management interface

Management is used for the initial setup of the router and for troubleshooting. Most routers provide a console port, which is an EIA-232 asynchronous serial port. Some routers include an auxiliary port. A rollover cable and an RJ-45 to DB-9 adapter are used to connect the router console port to a PC.

In a LAN environment, the router is a host that communicates with the LAN through a hub or a switch. It is connected using a straight-through cable. A WAN is a little more complicated. The DTE is connected from the CPE to the service provider through a DCE device, which is typically a modem or CSU/DSU. This device converts the data from the DTE to a form recognized by the service provider. WAN services include leased line, circuit-switched, or packet-switched. Four considerations are used to select the proper cable:

• The type of connection to the Cisco device
• The type of network system that will be connected, which is DTE or DCE
• The signaling standard
• The type of connector on the cable

Connecting WAN interfaces

Connecting WAN interfaces
1.2.7 This page discusses the different forms of WAN connections.


A WAN uses many different technologies to make data connections across a broad geographic area. WAN communication services are usually leased from service providers. WAN connection types include leased line, circuit-switched, and packet-switched.

For each type of WAN service, the customer premises equipment (CPE), which is often a router, is the DTE. This is connected to the service provider through a DCE device, which is commonly a modem or CSU/DSU. This device is used to convert the data from the DTE into a form acceptable to the WAN service provider.

Perhaps the most commonly used router interfaces for WAN services are serial interfaces. Answer the following questions to select the proper serial cable:

• What is the type of connection to the Cisco device? Cisco routers may use different connectors for the serial interfaces. The interface on the left is a Smart Serial interface. The interface on the right is a DB-60 connection. It is important to select the correct serial cable to connect the network system to the serial devices. This is a critical part in setting up a WAN.

• Is the network system connected to a DTE or DCE device? DTE and DCE are the two types of serial interfaces that devices use to communicate. The key difference between these two is that the DCE device provides the clock signal for the communications on the bus. The device documentation should specify whether it is DTE or DCE.

• Which signaling standard does the device require? For each different device, a different serial standard could be used. Each standard defines the signals on the cable and specifies the connector at the end of the cable. Device documentation should always be consulted for the signaling standard.

• Is a male or female connector required on the cable? If the connector has visible projecting pins, it is male. If the connector has sockets for projecting pins, it is female.

This page concludes Module 1. The next page will provide a summary of the main points from this module.

Console port connections / Connecting router LAN interfaces

Console port connections
1.2.5 This page will provide more information about the console port.


The console port is a management port that is used to provide out-of-band access to a router. It is used to set up the initial configuration of a router and to monitor it. The console port is also used for disaster recovery procedures.

A rollover cable and an RJ-45 to DB-9 adapter are used to connect a PC to the console port. Cisco supplies the necessary adapter to connect to the console port.

The PC or terminal must support VT100 terminal emulation. Terminal emulation software such as HyperTerminal is usually used.

The following are steps to connect a PC to a router:

1. Configure terminal emulation software on the PC for the following:

• The appropriate COM port
• 9600 baud
• 8 data bits
• No parity
• 1 stop bit
• No flow control

2. Connect the RJ-45 connector of the rollover cable to the router console port.

3. Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter.

4. Attach the female DB-9 adapter to a PC.

Connecting router LAN interfaces
1.2.6 This page will teach students how to connect LAN interfaces.


A router is usually connected to a LAN through an Ethernet or Fast Ethernet interface. The router is a host that communicates with the LAN through a hub or a switch. A straight-through cable is used to make this connection. A 10BASE-TX or 100BASE-TX router interface requires Category 5, or better, unshielded twisted-pair (UTP) cable, regardless of the router type.

In some cases the Ethernet connection of the router is connected directly to the computer or to another router. For this type of connection, a crossover cable is required.

The correct interface must be used. If the wrong interface is connected, it can damage the router or other networking devices. Many different types of connections use the same style of connector. For example Ethernet, ISDN BRI, console, AUX, integrated CSU/DSU, and Token Ring interfaces use the same eight-pin connector, which is RJ-45, RJ-48, or RJ-49. Students can use the Lab Activity and the Interactive Media Activity to practice LAN interface connections.

The next page will discuss WAN interface connections.

Management port connections

Management port connections
1.2.4 This page will introduce the console and auxiliary (AUX) ports, which are also known as the management ports. These asynchronous serial ports are not designed as networking ports. The console port is required for the configuration of the router. Not all routers have an auxiliary port.


When the router is first put into service, there are no networking parameters configured. Therefore the router cannot communicate with any network. To prepare for initial startup and configuration, attach an RS-232 ASCII terminal, or attach the rollover cable to a personal computer running terminal emulating software such as HyperTerminal, to the system console port. Then configuration commands can be entered to set up the router.

After the initial configuration is entered into the router through the console or auxiliary port, the router can be connected to the network to troubleshoot or monitor it.

The router can also be remotely configured through the configuration port across an IP network using Telnet or by dialing to a modem connected to the console or auxiliary port on the router.

The console port is also preferred over the auxiliary port for troubleshooting. This is because it displays router startup, debugging, and error messages by default. The console port can also be used when the networking services have not been started or have failed. Therefore, the console port can be used for disaster and password recovery procedures.

The next page contains more information about console ports.

Router physical characteristics / Router external connections

Router physical characteristics
1.2.2 This page will help students identify the location of different components on a router.


It is not critical to know the location of the physical components inside the router to understand how to use the router. However in some situations, such as adding memory, it can be very helpful.

The exact components used and their location varies between router models. Figure identifies the internal components of a 2600 router.

Figure shows some of the external connectors on a 2600 router.

The next page will describe the external connections on a router.

Router external connections
1.2.3 This page will describe the three basic types of connections on a router, which are LAN interfaces, WAN interfaces, and management ports.


LAN interfaces allow routers to connect to the LAN media. This is usually some form of Ethernet. However, it could be some other LAN technology such as Token Ring or FDDI.

WANs provide connections through a service provider to a distant site or to the Internet. These may be serial connections or any number of other WAN interfaces. With some types of WAN interfaces, an external device such as a CSU is required to connect the router to the local connection of the service provider. With other types of WAN connections, the router may be directly connected to the service provider.

The function of management ports is different from the other connections. The LAN and WAN connections provide network connections through which packets are forwarded. The management port provides a text-based connection for the configuration and troubleshooting of the router. The common management interfaces are the console and auxiliary ports. These are EIA-232 asynchronous serial ports. They are connected to a communications port on a computer. The computer must run a terminal emulation program to provide a text-based session with the router. Through this session the network administrator can manage the device.

The next page will provide a detailed explanation of management ports.