IPv6 Routing | 453IPv6 Neighbor DiscoveryIPv6 NDP is supported on platforms c e s zNeighbor Discovery Protocol (NDP) is a top-level protocol for neighbor discovery on an IPv6 network. Inlieu of ARP, NDP uses “Neighbor Solicitation” and “Neighbor Advertisement” ICMPv6 messages fordetermining relationships between neighboring nodes. Using these messages, an IPv6 device learns thelink-layer addresses for neighbors known to reside on attached links, quickly purging cached values thatbecome invalid.With ARP, each node broadcasts ARP requests on the entire link. This approach causes unnecessaryprocessing by uninterested nodes. With NDP, each node sends a request only to the intended destinationvia a multicast address with the unicast address used as the last 24 bits. Other hosts on the link do notparticipate in the process, greatly increasing network bandwidth efficiency.Figure 21-3. NDP Router RedirectNote: If a neighboring node does not have an IPv6 address assigned, it must be manually pinged to allowthe IPv6 device to determine the relationship of the neighboring node.Note: To avoid problems with network discovery, Dell Force10 recommends configuring the static routelast or assigning an IPv6 address to the interface and assigning an address to the peer (the forwardingrouter’s address) less than 10 seconds apart.
