Stateless Autoconfiguration Engineering Workshops Why does this matter

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Stateless Autoconfiguration Engineering Workshops

Stateless Autoconfiguration Engineering Workshops

Why does this matter? • Manual configuration of individual machines before connecting them to

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 Engineering Workshops

Stateless Autoconfiguration Generate a link local address Verify this tentative address Is ok. Use

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 Fail and go to manual Configuration or choose A different interface token If no response Assign the address to the Interface. At this point the Node can communicate On-link. Engineering Workshops

Stateless Autoconfiguration Assign address to Interface. Node joins the All Routers Multicast group. FF

Stateless Autoconfiguration Assign address to Interface. Node joins the All Routers Multicast group. FF 02: : 1 Sends out a router Solicitation message to That group. ICMP type 133 Router responds with a Router advertisement. ICMP type 134 Engineering Workshops

Stateless Autoconfiguration Look at the “managed address configuration" flag If M= 0 proceed with

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

Router Solicitation Type = 133 Code = 0 Checksum Reserved Possible options: Source link

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

Router Advertisement Type = 134 Code = 0 Cur Hop Limit M O Reserved

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

Neighbor Solicitation Type = 135 Code = 0 Checksum Reserved Target Address Possible Option:

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

Neighbor Advertisment Type = 136 Code = 0 Checksum RSO Reserved Target Address Possible

Neighbor Advertisment Type = 136 Code = 0 Checksum RSO Reserved Target Address Possible Option: Source Link Layer Address Engineering Workshops

Prefix Option type length Prefix length L A Reserved Valid Lifetime Preferred Lifetime reserved

Prefix Option type length Prefix length L A Reserved Valid Lifetime Preferred Lifetime reserved Prefix list Engineering Workshops

Router Solicitation Options Prefix Information • This should include all prefixes the router is

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 Engineering Workshops

Router Solicitation Options Prefix Information • Valid Lifetime – 32 -bit unsigned integer. The

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. Engineering Workshops

Stateless autoconfig • Routers are to send out router advertisements at regular intervals at

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. Engineering Workshops

Stateful configuration • When you do not wish to have stateless configuration done you

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. Engineering Workshops