HP 2520-8 Configuration Manual page 25

N o t e :
Track neighbor (local) routers.
■
Neighbor Discovery enables functions such as the following:
■ router and neighbor solicitation and discovery
■ detecting address changes for devices on a VLAN
identifying a replacement for a router or router path that has become
■
unavailable
■ duplicate address detection (DAD)
■ router advertisement processing
neighbor reachability
■
■ autoconfiguration of unicast addresses
■ resolution of destination addresses
changes to link-layer addresses
■
An instance of Neighbor Discovery is triggered on a device when a new
(tentative) or changed IPv6 address is detected. (This includes stateless,
stateful, and static address configuration.) ND operates in a per-VLAN scope;
that is, within the VLAN on which the device running the ND instance is a
member. Neighbor discovery actually occurs when there is communication
between devices on a VLAN. That is, a device needing to determine the link-
layer address of another device on the VLAN initiates a (multicast) neighbor
solicitation message (containing a solicited-node multicast address that corre-
sponds to the IPv6 address of the destination device) on the VLAN. When the
destination device receives the neighbor solicitation, it responds with a
neighbor advertisement message identifying its link-layer address. When the
initiating device receives this advertisement, the two devices are ready to
exchange traffic on the VLAN interface. Also, when an IPv6 interface becomes
operational, it transmits a router solicitation on the interface and listens for a
router advertisement.
Neighbor and router solicitations must originate on the same VLAN as the
receiving device. To support this operation, IPv6 is designed to discard any
incoming neighbor or router solicitation that does not have a value of 255 in
the IP Hop Limit field. For a complete list of requirements, refer to RFC 246.
When a pair of IPv6 devices in a VLAN exchange communication, they enter
each other's IPv6 and corresponding MAC addresses in their respective
neighbor caches. These entries are maintained for a period of time after
communication ceases, and then dropped.
To view or clear the content of the neighbor cache, refer to "Configuring a
Static IPv6 Address on a VLAN" on page 1-9.
IPv6 Addressing Configuration
Neighbor Discovery (ND)
1-13