IPv 6 Prefix Delegation Options for DHCPv 6
- Slides: 12
IPv 6 Prefix Delegation Options for DHCPv 6 Ole Troan, Ralph Droms IETF-53 1
PD Options for DHCPv 6 • New options for DHCPv 6 for delegation of prefixes – Prefix Request option: Requesting Router indicates interest in obtaining prefixes – Prefix Delegation option: Delegating Router assigns prefixes to Requesting Router IETF-53 2
Delegation from ISP to subscriber AAA service Delegating router ISP core network Aggregation device CPE Requesting router Subscriber link IETF-53 Subscriber link 3
Initial delegation • Requesting router indicates interest in prefix delegation by including Prefix Request in Solicit message • Delegating router indicates availability of prefix(es) by including Prefix option in Advertise message • Requesting router asks for prefix(es) in Request message • Delegating router delegates prefixes by including Prefix option in Reply message IETF-53 4
Delegation extension • Requesting router requests extension of lease on prefix(es) in Rebind/Renew message • Delegating router extends lease in Reply message IETF-53 5
Prefix Request option format 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_PREFIXREQ | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | prefix-length | num-global | num-site | +-+-+-+-+-+-+-+-+-+-+-+-+ num-global – number of global prefixes requested num-site – number of site-scoped prefixes requested IETF-53 6
Prefix Option format 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_IAPREFIX | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | lease-duration | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | prefix-length | IPv 6 -prefix | +-+-+-+-+ (variable length) |. . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ lease-duration – controlled by delegating router; requesting router derives preferred and valid lifetimes IPv 6 -prefix – padded to even octet boundary (/35 prefix occupies 5 octets) IETF-53 7
Collateral damage from DHCPv 6 • Clearly defined rules for use of DHCP messages when requesting router restarts, reconnects to link, etc. • DUID from DHCP allows delegating router to identify requesting router – for example, for lease renewal or static prefix assignment • Relay function and use of multicast allows for centralized service implementation • DHCP can carry other configuration information; spec includes process for defining additional options • Reconfigure message allows forced renumbering IETF-53 8
Status of DHCPv 6 specification • Specification has passed WG last call • Internet AD has responded with editorial comments • Authors will rev spec and publish new draft • Next rev of spec will be ready for IETF last call IETF-53 9
Simplifying DHCP • Requesting and delegating routers can implement prefix delegation function without address assignment or “identity associations” • IPsec with link-local addresses (may) eliminate need for DHCP authentication • Only a subset of messages and protocol specification required for prefix delegation and configuration • Guidelines for prefix delegation and configuration requirements to be published as Internet Draft IETF-53 10
Open Issues • Two message exchange (Informationrequest/Reply) for prefix delegation • Use of IPsec for authentication if requesting router has address of appropriate scope • Use of anycast (e. g. , for NBMA networks) • Name: Dynamic Host Configuration Protocol – – IETF-53 Dynamic Node Configuration Protocol? Dynamic Configuration Protocol? Simple Configuration Protocol? Droms-Haberman Configuration Protocol? 11
Delegation from ISP to subscriber AAA service f. Authenticate Aggregation ISP core network device Authorizeg Advertisei i. Reply Solicith h. Request CPE is assigned 2000: 0: 100: : /48 CPE assigns 2000: 0: 100: 1: /64 and 2000: 0: 100: 2: /64 to other “downstream” interfaces IETF-53 CPE Subscriber link 12