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Lower Layer Independence Desirable for hosts to be able to configure themselves on multiple networks without adding configuration code specific to a new link layer. Multi-homed hosts becoming popular Examples: WWAN/WLAN phones Counter-examples RFC 903 (RARP) RFC 1661 (PPP IPCPv4) Assigns IP addresses instead of using BOOTP/DHCP NAS devices did not act as BOOTP/DHCP servers at the time (now common) IPv6CP (RFC 2472) only assigns link identifier, not prefix RFC 1877 (IPCPv4 Extensions for Name Service Configuration) PPPEXT WG has resisted equivalent IPv6CP extensions IPCP allocation no longer FCFS, requires IETF Consensus (RFC 3818) DHCPINFORM can be implemented over PPP instead IKEv2 CFG_REQUEST/REPLY (Section 2.19, 3.15) Allows IKEv2 peer to request configuration from its peer Support for configuration of IPv4/IPv6 address, netmask, prefix, DHCPv4/v6 server, DNS server, WINS server, routes WINS not even defined for IPv6! Need to avoid chicken/egg problem (need inner address to configure tunnel mode SA, but can’t obtain inner address without a tunnel mode SA) Alternative mechanism still needed for other configuration parameters Alternative is multi-stage setup, snopping of IP address configuration by VPN server (RFC 3456) |