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ISCOM2600G-HI (A) Series Configuration Guide
5.4 NDP
5.4.1 Introduction
Neighbor Discovery Protocol (NDP) is a neighbor discovery mechanism used on IPv6 devices
in the same link. It is used to discover neighbors, obtain MAC addresses of neighbors, and
maintain neighbor information.
NDP obtains data link layer addresses of neighbor devices in the same link, namely, MAC
address, through the Neighbor Solicitation (NS) message and Neighbor Advertisement (NA)
message.
Figure 5-3 Principles of NDP address resolution
As shown in Figure 5-3, take Switch A for example. Switch A obtains the data link layer
address of Switch B as below:
Step 1 Switch A sends a NS message in multicast mode. The source address of the NS message is the
IPv6 address of Layer 3 interface on Switch A, and the destination address of the NS message
is the multicast address of the requested node of the Switch B. The NS message even contains
the data link layer address of Switch A.
Step 2 After receiving the NS message, Switch B judges whether the destination address of the NS
message is the multicast address of the request node corresponding to the IPv6 address of
Switch B. If yes, Switch B can obtain the data link layer address of Switch A, and sends a NA
message which contains its data link layer address in unicast mode.
Step 3 After receiving the NA message from Switch B, Switch A obtains the data link layer address
of Switch B.
By sending ICMPv6 message, IPv6 NDP even has the following functions:
5.4.2 Preparing for configurations
Scenario
IPv6 NDP not only implements IPv4 ARP, ICMP redirection, and ICMP device discovery, but
also supports detecting whether the neighbor is reachable.
Verify whether the neighbor is reachable.
Detect duplicated addresses.
Discover routers or prefix.
Automatically configure addresses.
Support redirection.
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