Users Guide

Neighbor Discovery Protocol (NDP)

The neighbor discovery protocol for IPv6 is dened in RFC 2461 as part of the Stateless Address Autoconguration protocol. It replaces the

Address Resolution Protocol used with IPv4. NDP denes mechanisms for solving the following problems:

• Router discovery — hosts can locate routers residing on a link

• Prex discovery — hosts can discover address prexes for the link

• Parameter discovery

• Address autoconguration — conguration of addresses for an interface

• Address resolution — mapping from IP address to link-layer address

• Next-hop determination

• Neighbor unreachability detection (NUD) — determine that a neighbor is no longer reachable on the link.

• Duplicate address detection (DAD) — allow a node to check whether a proposed address is already in use.

• Redirect — the router can inform a node about a better rst-hop.

NDP uses the following ve ICMPv6 packet types in its implementation:

• Router Solicitation

• Router Advertisement

• Neighbor Solicitation

• Neighbor Advertisement

• Redirect

IPv6 Router Advertisement (RA) Guard

The IPv6 RA guard provides support to perform conditional forwarding or blocking of the router advertisement messages that are received

at the network device platform. This functionality analyzes and lters the RAs sent by the devices and compares the conguration

information on the layer 2 device with the RA frame. Once the layer 2 device validates the content of the RA frame against the

conguration, it forwards the RA to its unicast or multicast destination. On failure to validate the RA frame content, the RA frame is

dropped.

The IPv6 RA guard supports two dierent modes:

• Host mode — When a policy with device role as host is applied on an interface, all the RA packets are dropped without validation. You

can also congure the host mode policy with VLAN option to drop the RA packets on that specic VLAN and port.

• Router mode — When a policy with device role as router is applied on an interface, all the RA packets are validated based on the

conguration information in the policy. Similarly, you can also apply this mode over any specic VLAN and the validation is performed

only for that particular VLAN RA packets.

To congure the IPv6 RA guard, use the following Dell Networking OS commands.

Neighbor Discovery Protocol (NDP) 1003