1. Bootstrap And Autoconfiguration (BOOTP, DHCP)

2. System Startup IP stack designed with many parameters
IPv4 or IPv6 address
an address mask,
network prefix,
addresses of a default router
addresses of a name server.
Values filled in when system starts

3. Two possible sources of information
System Startup
Two possible sources of information
Local storage device (e.g., disk)
Server on the network

4. RARP ???

5. RARP - Disadvantage direct access to the network hardware
reply contains only one small piece of information, client's 4- octet IP address
it cannot be used on networks that dynamically assign hardware addresses.

6. BOOTstrap Protocol (BOOTP)
Dynamic Host Configuration Protocol (DHCP)
Neighbor Discovery Protocol (NDP, IPv6 – ND)

7. BOOTstrap Protocol (BOOTP)
Early alternative to RARP
BOOTP operates in the client-server paradigm and requires only a single packet exchange.
Obtained configuration parameters from a server - IP address, the address of a router, and the address of a server.
Used UDP

8. Using IP To Determine An IP Address
BOOTP uses UDP to carry messages and that UDP messages are encapsulated in IP datagrams for delivery.
Destination ??
Reply??

9. The BOOTP Retransmission Policy
UDP uses IP for delivery
messages can be delayed, lost, delivered out of order, or duplicated
To guard against corruption, BOOTP requires that UDP use checksums.
To handle datagram loss, BOOTP uses the conventional technique of timeout and retransmission

10. BOOTP Message Format

11. Dynamic Host Configuration Protocol (DHCP)

12. Replaces and extends BOOTP
DHCP
Replaces and extends BOOTP

13. DHCP
DHCP allows a computer to acquire all the configuration information it needs in a single message
IP with Subnet Mask

14. DHCP allows a computer to obtain an IP address quickly and dynamically
manager must configure a DHCP server by supplying a set of IP addresses.

15. DHCP DHCP used to obtain parameters for an IP stack
DHCP uses IP and UDP to obtain the parameters
Stack must be initialized before being initialized

16. DHCP runs as application Using IP To Determine An IP Address
Limited Broadcast
Using IP To Determine An IP Address
Uses UDP to carry messages

17. Retransmission Policy
Client handles retransmission
Initial timeout selected at random
Timeout for successive retransmissions doubled

18. DHCP Server not in Local Network??
Relay Agent

19. DHCP address assignment
manual configuration
manager can configure specific address for a specific computer
automatic configuration
DHCP server assign a permanent address when a computer first attaches to the network
dynamic configuration
server "loans" an address to a computer for a limited time

20. Dynamic Address Assignment
Client is granted a lease on an address
Server specifies length of lease
At end of lease, client must renew lease or stop using address
Actions controlled by finite state machine

21. DHCP Address Acquisition States

22. DHCP Message Format

23. DHCP Options And Message Type