Introduction to Computer Networking

1. Introduction to Computer Networking M Clements ITCN

2. Last Week ……… • Virtual Week • All outstanding work completed • Hopefully! 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 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 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. 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 ITCN

7. Password Configuration ITCN

8. Adds, Moves, and Changes 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:\ ITCN

10. Using the copy running-config tftp Command ITCN

11. Using the copy tftp running-config Command 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 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 ITCN

14. Parallel Data Transfer ITCN

15. Serial Data Transfer 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 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 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 ITCN

19. Serial cables Each cable has a DCE end and a DTE end Clearly marked – do not mix up 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 ITCN