Address resolution, Neighbor reachability detection, Table 8 – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
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Table 8 ICMPv6 messages used by ND
ICMPv6 message
Type
Function
Neighbor Solicitation (NS)
message
135
Acquires the link-layer address of a neighbor.
Verifies whether a neighbor is reachable.
Detects duplicate addresses.
Neighbor Advertisement
(NA) message
136
Responds to an NS message.
Notifies the neighboring nodes of link layer changes.
Router Solicitation (RS)
message
133
Requests for an address prefix and other configuration
information for autoconfiguration after startup.
Router Advertisement (RA)
message
134
Responds to an RS message.
Advertises information such as the Prefix Information options and
flag bits.
Redirect message
137
Informs the source host of a better next hop on the path to a
particular destination when certain conditions are satisfied.
Address resolution
This function is similar to the ARP function in IPv4. An IPv6 node acquires the link-layer addresses of
neighboring nodes on the same link through NS and NA message exchanges.
shows how
Host A acquires the link-layer address of Host B on a single link.
Figure 46 Address resolution
The address resolution operates in the following steps.
1.
Host A multicasts an NS message. The source address of the NS message is the IPv6 address of the
sending interface of Host A and the destination address is the solicited-node multicast address of
Host B. The NS message contains the link-layer address of Host A.
2.
After receiving the NS message, Host B judges whether the destination address of the packet is its
solicited-node multicast address. If yes, Host B learns the link-layer address of Host A, and then
unicasts an NA message containing its link-layer address.
3.
Host A acquires the link-layer address of Host B from the NA message.
Neighbor reachability detection
After Host A acquires the link-layer address of its neighbor Host B, Host A can use NS and NA messages
to check whether Host B is reachable.
1.
Host A sends an NS message whose destination address is the IPv6 address of Host B.