Ch. 28 (CCNA 2001-301) vol 1: Implementing IPv6 Addressing on Hosts

Duplicate Address Detection (DAD)

A term used in IPv6 to refer to how hosts first check whether another host is using a unicast address before the first host uses that address.

IPv6 neighbor table

The IPv6 equivalent of the ARP table. A table that lists IPv6 addresses of other hosts on the same link, along with their matching MAC addresses, as typically learned using Neighbor Discovery Protocol (NDP).

Neighbor Advertisement (NA)

A message defined by the IPv6 Neighbor Discovery Protocol (NDP), used to declare to other neighbors a host's MAC address. Sometimes sent in response to a previously received NDP Neighbor Solicitation (NS) message.

Neighbor Discovery Protocol (NDP)

A protocol that is part of the IPv6 protocol suite, used to discover and exchange information about devices on the same subnet (neighbors). In particular, it replaces the IPv4 ARP protocol.

Neighbor Solicitation (NS)

A message defined by the IPv6 Neighbor Discovery Protocol (NDP), used to ask a neighbor to reply with a Neighbor Advertisement, which lists the neighbor's MAC address.

on-link prefix

An IPv6 subnet prefix, advertised by a router in an NDP Router Advertisement (RA) message, that identifies to on-link hosts a subnet considered to exist on the local link.

permanent IPv6 address

When using IPv6 SLAAC, a host creates an address with an infinite preferred and valid lifetime, making the address permanent, using the address when listening for incoming connections to any services running on that host.

preferred lifetime

In the context of IPv6 addresses, a timer applied to a SLAAC-created address defining how long the address is preferred, meaning the host uses the address for new and existing application flows.

Prefix Discovery

IPv6 neighbor discovery protocol (NDP) function, specifically part of the Router Advertisement (RA) message, in which the router supplies a list of IPv6 subnet prefixes and prefix lengths that exist on the local link.

Router Advertisement (RA)

A message defined by the IPv6 Neighbor Discovery Protocol (NDP), used by routers to announce their willingness to act as an IPv6 router on a link. These can be sent in response to a previously received NDP Router Solicitation (RS) message.

Router Solicitation (RS)

A message defined by the IPv6 Neighbor Discovery Protocol (NDP), used to ask any routers on the link to reply, identifying the router, plus other configuration settings (prefixes and prefix lengths).

stateful DHCPv6

A term used in IPv6 to contrast with stateless DHCP. Stateful DHCP keeps track of which clients have been assigned which IPv6 addresses (state information).

Stateless Address Autoconfiguration (SLAAC)

A feature of IPv6 in which a host or router can be assigned an IPv6 unicast address without the need for a stateful DHCP server.

Stateless DHCPv6

A term used in IPv6 to contrast with stateful DHCP. Stateless DHCP servers don't lease IPv6 addresses to clients. Instead, they supply other useful information, such as DNS server IP addresses, but with no need to track information about the clients (state information).

temporary IPv6 address

When using IPv6 SLAAC, a host creates an address with a relatively short preferred and valid lifetime, usually days long for each, making the address temporary. The host uses the temporary address for outgoing application connections.

valid lifetime

In the context of IPv6 addresses, a timer applied to a SLAAC-created address defining how long the address is valid, meaning the host can continue to support existing application flows using the address.