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Dynamic Host Configuration Protocol for IPv6

• draft-ietf-dhc-dhcpv6-28.txt (currently with RFC-Editor) • Similar to DHCPv4, but
– – – – Supports IPv6 addressing and configuration needs Is the “stateful” auto-configuration protocol for IPv6 (“M” bit) Is the “other” (non-address) configuration protocol for IPv6 (“0” bit) Clean design • New optimized packet format (no BOOTP legacy) • 16-bit option space, 16-bit option lengths • Uses encapsulation (some messages/options encapsulate others) – Client may obtain many addresses (not just one)
2003/01/20 1

EUD/X/PD AD03:0117 Rev PA8

nodes use DHCPv6 to obtain addresses and more – These are not mutually exclusive! – Duplicate address detection (DAD) used to avoid duplicated addresses • Link-local address always available – A node always creates a link-local address (stateless) – Allows for direct communication between nodes on a link – DHCPv6 client therefore has an address it can use EUD/X/PD AD03:0117 Rev PA8 2003/01/20 2 .IPv6 Concepts • IPv6 auto-configuration – Stateless .nodes configure addresses themselves with information from routers (if available). no managed addresses – Stateful .

routers update lifetimes • For stateful addresses. DHCPv6 server updates lifetimes (similar to DHCPv4 lease extension) EUD/X/PD AD03:0117 Rev PA8 2003/01/20 3 .IPv6 Concepts • IPv6 addresses have preferred & valid lifetimes – Preferred means address may be used to initiate communications – Valid means address is usable for communications (for existing connections or for pending queries) – After valid lifetime expires. address is no longer usable • For stateless addresses.

DHCPv6 Operation Solicit Advertise Client selects one Advertise .Server B’s Advertise Request Client can now use addresses and parameters for lifetimes T I M E Reply DHCP Server A DHCP Client Renew Client renews lifetimes starting at T1 time DHCP Server B Reply Release EUD/X/PD AD03:0117 Rev PA8 2003/01/20 4 Client releases addresses when shutting down .

provide client configuration information but no addresses – Confirm / Reply .assist in determining whether client moved – Reconfigure .More on DHCPv6 – Client sends messages to link-local multicast address – Server unicasts response to client – Information-Request / Reply .allow servers to initiate a client reconfiguration – Basic client/server authentication capabilities in base standard – DHCP Unique Identifier (DUID) used to identify clients & servers – Identity Association ID (IAID) used to identify a collection of addresses – Relay Agents used when server not on-link – Relay Agents may be chained EUD/X/PD AD03:0117 Rev PA8 2003/01/20 5 .

DHCPv6 Basic Message Format 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-type | transaction-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • SOLICIT • ADVERTISE • REQUEST • CONFIRM • RENEW • REBIND • REPLY EUD/X/PD AD03:0117 Rev PA8 2003/01/20 6 • RELEASE • DECLINE • RECONFIGURE • INFORMATION-REQUEST • RELAY-FORW • RELAY-REPL . (variable) . options .

DHCPv6 Option Format & Base Options 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-data | | (option-len octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • Client Identifier • Server Identifier • Identity Association for Non-temporary Addresses • Identity Association for Temporary Addresses • IA Address • Option Request • Preference • Elapsed Time • Relay Message EUD/X/PD AD03:0117 Rev PA8 2003/01/20 7 • Authentication • Server Unicast • Status Code • Rapid Commit • User Class • Vendor Class • Vendor-specific Information • Interface-Id • Reconfigure Message • Reconfigure Accept .