24 Feb 2009ITCN 1 Introduction to Computer Networking M Clements

24 Feb 2009 ITCN 2 Last Week ……… Virtual Week All outstanding work completed Hopefully!

24 Feb 2009 ITCN 3 This Week Other ways to login to a router TELNET, Console cable DCE and DTE Serial Data Links Saving router configurations TFTP server

24 Feb 2009 ITCN 4 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 2009 ITCN 5 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 2009 ITCN 6 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 2009 ITCN 7 Password Configuration

24 Feb 2009 ITCN 8 Adds, Moves, and Changes

24 Feb 2009 ITCN 9 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 2009 ITCN 10 Using the copy running- config tftp Command

24 Feb 2009 ITCN 11 Using the copy tftp running- config Command

24 Feb 2009 ITCN 12 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 2009 ITCN 13 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 2009 ITCN 14 Parallel Data Transfer

24 Feb 2009 ITCN 15 Serial Data Transfer

24 Feb 2009 ITCN 16 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 2009 ITCN 17 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 2009 ITCN 18 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 2009 ITCN 19 Serial cables Each cable has a DCE end and a DTE end Clearly marked – do not mix up

24 Feb 2009 ITCN 20 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