3Com MSR 50 Series Configuration Manual page 660

660 C 46: IP 6 B
HAPTER V ASICS
C
ONFIGURATION
"Neighbor reachability detection" on page 661
■
"Duplicate address detection" on page 661
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"Router/prefix discovery and address autoconfiguration" on page 662
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"Redirection" on page 663
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Table 38 lists the types and functions of ICMPv6 messages used by the NDP.
Table 38 Types and functions of ICMPv6 messages
ICMPv6 message
Neighbor solicitation (NS)
message
Neighbor advertisement (NA)
message
Router solicitation (RS)
message
Router advertisement (RA)
message
Redirect message
The NDP mainly provides the following functions:
Address resolution
Similar to the ARP function in IPv4, a node acquires the link-layer addresses of
neighbor nodes on the same link through NS and NA messages.
how node A acquires the link-layer address of node B.
Number Function
135 Used to acquire the link-layer address of a
neighbor
Used to verify whether the neighbor is
reachable
Used to perform a duplicate address
detection
136 Used to respond to an NS message
When the link layer changes, the local node
initiates an NA message to notify neighbor
nodes of the node information change.
133 After started, a node sends an RS message
to request the router for an address prefix
and other configuration information for the
purpose of autoconfiguration.
134 Used to respond to an RS message
With the RA message suppression disabled,
the router regularly sends an RA message
containing information such as address
prefix and flag bits
137 When a certain condition is satisfied, the
default gateway sends a redirect message
to the source host so that the host can
reselect a correct next hop router to
forward packets.
Figure 196 shows