2013년 9월 25일 수요일

DHCPv6

Fundamentals



  • DHCPv6 clients listen on port 546, servers and relays listen on port 547

  • DHCPv6 clients and servers (relays) communicate via link-local multicast addresses

    • All_DHCP_Relay_Agents_and_Servers and All_DHCP_Servers multicast addresses are used




All_DHCP_Relay_Agents_and_Servers : FF02:0:0:0:0:0:1:2(All-dhcp-agents)
IPv6 multicast MAC addresses : 33:33:00:01:00:02

DHCPv6 to DHCPv4 Message Comparison


-DHCPv6 Message Type                  -DHCPv4 Message Type 
SOLICIT (1) DHCPDISCOVER
ADVERTISE (2) DHCPOFFER
REQUEST (3), RENEW (5), REBIND (6) DHCPREQUEST
REPLY (7) DHCPACK / DHCPNAK
RELEASE (8) DHCPRELEASE
INFORMATION-REQUEST (11) DHCPINFORM
DECLINE (9) DHCPDECLINE
CONFIRM (4) none
RECONFIGURE (10) DHCPFORCERENEW
RELAY-FORW (12) none
RELAY-REPLY (13) none

Client Identification



  • DHCPv6 DUID (DHCP Unique Identifier) as defined in RFC3315

    • Link-layer address plus time - generated and stored at startup

    • Link-layer - generally used if network interface is permanent or unchangeable

    • Vendor assigned unique identifier based on enterprise identifier




DHCPv6 Type



  • Stateless DHCPv6

    • Two message exchange (INFORMATION-REQUEST, REPLY) between a DHCPv6 client and server
          Server  Client
      | <---- | INFORMATION-REQUEST
      | ----> | REPLY
      V V




  • Stateful DHCPv6

    • Four message exchange (SOLICIT, ADVERTISE, REQUEST, REPLY)

    • Rapid Commit may be employed which uses only two message (SOLICIT, REPLY)
          Server  Client
      | <---- | SOLICIT (Rapid Commit)
      | ----> | ADVERTISE
      | <---- | REQUEST
      | ----> | REPLY (Rapid Commit)
      V V