Neighbor Discovery Protocol

The Neighbor Discovery Protocol (NDP), as defined in RFC 2461, defines mechanisms for the following functions:

In IPv4, MAC address resolution is done by ARP. For IPv6, this functionality is handled by NDP. The router maintains a cache of IPv6 addresses and their corresponding MAC addresses and allows the system to respond to requests from other nodes for the MAC address of the IPv6 addresses configured on the interfaces.

Also supported is router discovery—the ability to send out router advertisements that can be used by a host to discover the router. The advertisements sent out contain the prefixes and configuration parameters that allow the end nodes to auto-configure their addresses. The switch also responds to requests from nodes for router advertisements.

The following settings can be configured on an interface to manage router advertisements:
  • Settings to control the sending of router advertisements over the interface periodically and to control responding to router solicitations
  • The maximum time between sending unsolicited router advertisements
  • The minimum time between sending unsolicited router advertisements
You can configure the following values, that are advertised by the switch:
  • Managed address configuration flag
  • Other stateful configuration flag
  • Link MTU
  • Retransmit timer
  • Current hop limit
  • Default lifetime
  • Reachable time
Additionally, you can configure the following values for each prefix on the prefix list associated with an interface:
  • Valid lifetime of the prefix
  • On-link flag
  • Preferred lifetime of the prefix
  • Autonomous flag


Unlike ExtremeWare, the ExtremeXOS software does not support host processing of neighbor router advertisements.