24 Feb 2009 ITCN1

Introduction to Computer Networking

M Clements

24 Feb 2009ITCN2

Last Week ………

Virtual Week All outstanding work completed Hopefully!

24 Feb 2009ITCN3

This Week

Other ways to login to a routerTELNET, Console cableDCE and DTESerial Data Links Saving router configurationsTFTP server

24 Feb 2009ITCN4

Logging into a router

Packet Tracer is TOO easy In a real situation, logging into a router will need to be

setup as part of configuration Off the shelf, you MUST login via a console cable and

a PC Console cable is often flat, blue and connected to the

RS232 (serial port) of a PC and the Console port of the router

Use a program such as hyperterminal

24 Feb 2009ITCN5

Establishing a Hyperterminal Session

All Cisco routers include an EIA/TIA-232 asynchronous serial console port (RJ-45).

Cables and adapters are needed to connect a console terminal (an ASCII terminal or PC running terminal emulation software) to the console port.

24 Feb 2009ITCN6

Using TELNET to login

TELNET is also commonly used Need to set up the TELNET line on the router 5 TELNET lines possible 0 – 4 Can be configured together or separately Need a TELNET password or no

communication is possible Remember TELNET is insecure

24 Feb 2009ITCN7

Password Configuration

24 Feb 2009ITCN8

Adds, Moves, and Changes

24 Feb 2009ITCN9

Saving your Router Configuration

Can be saved to NVRAM on router Can be saved on a PC Uses Trivial File Transfer Protocol TFTP Must configure a TFTP server on PC first Limited functionality given Always put server root in C:\

24 Feb 2009ITCN10

Using the copy running-config tftp Command

24 Feb 2009ITCN11

Using the copy tftp running-config Command

24 Feb 2009ITCN12

Long distance Data Transfer

Ethernet has limited range so can’t be used Must use another service E.g. modem, frame-relay, ATM Need to change line coding, voltages etc Line converter must be used Can be onboard router or external device Carries our data, but in a different format Translated back at far end of link

24 Feb 2009ITCN13

Crossing Distances

PC works using parallel buses Cannot use parallel for long distances Cable cost increases greatly Skew problems occur Solution is serial i.e. bit by bit

24 Feb 2009ITCN14

Parallel Data Transfer

24 Feb 2009ITCN15

Serial Data Transfer

24 Feb 2009ITCN16

DCE Data Circuit-Terminating Equipment or

Data Communication Equipment A DCE terminates a network circuit Converts bits received from the DTE to the

proper bit encoding for the network DCE provides bit clocking for the DTE DCE equipment includes modems,

CSUs/DSUs and switch interfaces

24 Feb 2009ITCN17

DTE Data Terminal Equipment Strictly the interface between PC parallel

circuitry and a serial device Serial devices: modem, CSU/ DSU Router serial interface is DTE PCs serial port is DTE

24 Feb 2009ITCN18

Identifying DTE and DCE

• DCE always has to be at each end of a long-distance or WAN link

•It converts serial data from PC to line voltages, coding etc used on the long-distance link

24 Feb 2009ITCN19

Serial cablesSerial cables

Each cable has a DCE end and a DTE endEach cable has a DCE end and a DTE end

Clearly marked – do not mix upClearly marked – do not mix up

24 Feb 2009ITCN20

Summary

Login via TELNET or Console cable Setup console & TELNET passwords first DCEs always go in pairs at each end of a long

distance data connection DTE is serial connection on PC/ router Can use a TFTP server to

– save or load configurations– Upgrade IOS version