1. Engineering Workshops Stateless Autoconfiguration

2. Engineering Workshops Why does this matter? Manual configuration of individual machines before connecting them to the network should not be required. –Address autoconfiguration assumes that each interface can provide a unique identifier for that interface (i.e., an "interface token") Plug-and-play communication is achieved through the use of link-local addresses –Small sites should not need stateful servers A large site with multiple networks and routers should not require the presence of a stateful address configuration server. Address configuration should facilitate the graceful renumbering of a site's machines

3. Engineering Workshops Stateless Autoconfiguration Generate a link local address Verify this tentative address Is ok. Use a neighbor solicitation with the tentative address as the target. ICMP type 135 If the address is in use a neighbor advertisement Message will be returned. ICMP type 136 If no response Assign the address to the Interface. At this point the Node can communicate On-link. Fail and go to manual Configuration or choose A different interface token

4. Engineering Workshops Stateless Autoconfiguration Assign address to Interface. Node joins the All Routers Multicast group. FF02::1 Sends out a router Solicitation message to That group. ICMP type 133 Router responds with a Router advertisement. ICMP type 134

5. Engineering Workshops Stateless Autoconfiguration Look at the “managed address configuration" flag If M= 0 proceed with Stateless configuration If M=1 stop and Do statefull config. Look at "other stateful configuration" flag If O = 0 finish If O= 1 use statefull Configuration for other information

6. Engineering Workshops Router Solicitation Type = 133Code = 0Checksum Reserved Possible options: Source link layer Address

7. Engineering Workshops Router Advertisement Type = 134Code = 0Checksum Cur Hop LimitM O Reserved Router Lifetime Reachable TIme Retransmission Timer Possible Options: -Source Link Layer address -MTU -Prefix Information

8. Engineering Workshops Neighbor Solicitation Type = 135Code = 0Checksum Reserved Target Address Possible Option: Source Link Layer Address

9. Engineering Workshops Neighbor Advertisment Type = 136Code = 0Checksum R S O Reserved Target Address Possible Option: Source Link Layer Address

10. Engineering Workshops Prefix Option typelengthPrefix lengthL A Reserved Valid Lifetime Preferred Lifetime reserved Prefix list

11. Engineering Workshops Router Solicitation Options Prefix Information This should include all prefixes the router is aware of Flag bits: –On-link = 1 Prefix is specific to the local site –Autonomous Configuration bit = 1 Use the prefix to create an autonomous address

12. Engineering Workshops Router Solicitation Options Prefix Information Valid Lifetime –32-bit unsigned integer. The length of time in seconds before an address is invalidated. Preferred Lifetime –32-bit unsigned integer. The length of time in seconds before an address is depreciated.

13. Engineering Workshops Stateless autoconfig Routers are to send out router advertisements at regular intervals at the all hosts address. –This should update lifetimes. Note that stateless autoconfig will only configure addresses. –It will not do all the host configuration you may well want to do.

14. Engineering Workshops Stateful configuration When you do not wish to have stateless configuration done you will need to provide a configuration server (DHCP most likely) to provide configuration information to the hosts as they come up.