F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Network Management Configuration Guide-6PW100

672
ICMPv6 messa
g
e T
yp
e Function
Neighbor Advertisement
(NA) message
136
Responds to an NS message.
Notifies the neighboring nodes of link layer changes.
Router Solicitation (RS)
message
133
Requests 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.
1676BAddress 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.
2852HFigure 358 shows how
Host A acquires the link-layer address of Host B on a single link.
Figure 358 Address resolution
The address resolution operates as follows:
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 determines 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.
1677BNeighbor 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.
2. If Host A receives an NA message from Host B, Host A decides that Host B is reachable. Otherwise,
Host B is unreachable.