DHCP - PowerPoint PPT Presentation

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  1. DHCP MM Clements

  2. Last Week ………… • Protocol architecture needed to contain a set of communication rules • TCP/ IP dominates world communications • SMTP, FTP & TELNET all rely on TCP/ IP • Port numbers are associated with application processes in Transport Layer • IP addressing is dealt with in the Internet layer ENS

  3. This Week ………. • Dynamic Host Configuration Protocol • Automatic provision of information to clients at boot • Comparison with BOOTP • Sequence of operation • Practical work ENS

  4. DHCP DHCP works by providing a process for a server to allocate the IP information to clients. Clients lease the information from the server for an administratively defined period. ENS

  5. BOOTP and DHCP Differences • DHCP defines mechanisms through which clients can be assigned an IP address for a finite lease period. • This lease period allows for re-assignment of the IP address to another client later, or for the client to get another assignment, if the client moves to another subnet. ENS

  6. DHCP vs. BOOTP • Clients may also renew leases and keep the same IP address. • DHCP provides the mechanism for a client to gather other IP configuration parameters, such as WINS and domain name. ENS

  7. Major DHCP Features • Automatic Allocation • Manual Allocation • Dynamic Allocation ENS

  8. DHCP Operation ENS

  9. The Order of DHCP Message Transmission ENS

  10. Packet Tracer’s DHCP server ENS

  11. DHCP setup in PT 5.2 • Needs a pool name to identify the range • Needs a default gateway • Need DNS server IP address • Needs the subnet mask • Needs a start address • Needs a total user number ENS

  12. PT 5.2 DHCP Interface Details of the LAN can be entered into the DHCP settings tab of Packet Tracer 5.2. ENS

  13. Domain Name System • The domain name system uses a client/ server approach to the problem. • Your computer sends a request to a domain name server: • What is the IP address for www.gre.ac.uk ? • The server looks up the corresponding IP number and replies: • ENS

  14. Domain Name System • Maps IP addresses to URLs • Replaces original hosts.txt file (history) • A-Record maps IP to URL • Extra URLs can be mapped to original URL using CNAME (canonical name) • System is used globally – is open to abuse - beware ENS

  15. Packet Tracer’s DNS tab ENS

  16. More DNS next week ENS

  17. Conclusion • DHCP widely used • Successor to BOOTP • Provides basic IP addressing information to PCs • Addresses leased from server • Can be implemented on server or router ENS