Neighbor Discovery Protocol
The Neighbor Discovery Protocol (NDP), as defined in RFC 2461, defines mechanisms for the
following functions:
- Resolving link-layer addresses of the IPv6 nodes residing on the
link.
- Locating routers residing on the attached link.
- Locating the address prefixes that are located on the attached
link.
- Learning link parameters such as the link MTU, or Internet parameters
such as the hop limit value that has to be used in the outgoing packets.
- Automatic configuration of the IPv6 address for an interface.
- Detecting whether the address that a node wants to use is already in
use by another node, also known as Duplicate Address Detection (DAD).
- Redirecting the traffic to reach a particular destination through a
better first-hop.
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
Note
Unlike ExtremeWare, the ExtremeXOS software does not
support host processing of neighbor router advertisements.
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