Cisco ASA 5505 Configuration Manual page 476

Configuring Neighbor Solicitation Messages
Information About Neighbor Solicitation Messages
Neighbor solicitation messages (ICMPv6 Type 135) are sent on the local link by nodes attempting to
discover the link-layer addresses of other nodes on the local link. The neighbor solicitation message is
sent to the solicited-node multicast address. The source address in the neighbor solicitation message is
the IPv6 address of the node sending the neighbor solicitation message. The neighbor solicitation
message also includes the link-layer address of the source node.
After receiving a neighbor solicitation message, the destination node replies by sending a neighbor
advertisement message (ICPMv6 Type 136) on the local link. The source address in the neighbor
advertisement message is the IPv6 address of the node sending the neighbor advertisement message; the
destination address is the IPv6 address of the node that sent the neighbor solicitation message. The data
portion of the neighbor advertisement message includes the link-layer address of the node sending the
neighbor advertisement message.
After the source node receives the neighbor advertisement, the source node and destination node can
communicate.
Figure 25-1
ICMPv6 Type = 135
Src = A
Dst = solicited-node multicast of B
Data = link-layer address of A
Query = what is your link address?
Neighbor solicitation messages are also used to verify the reachability of a neighbor after the link-layer
address of a neighbor is identified. When a node wants to verifying the reachability of a neighbor, the
destination address in a neighbor solicitation message is the unicast address of the neighbor.
Neighbor advertisement messages are also sent when there is a change in the link-layer address of a node
on a local link. When there is such a change, the destination address for the neighbor advertisement is
the all-nodes multicast address.
Licensing Requirements for Neighbor Solicitation Messages
The following table shows the licensing requirements for this feature:
Model License Requirement
All models Base License.
Cisco ASA 5500 Series Configuration Guide using ASDM
25-2
Figure 25-1 shows the neighbor solicitation and response process.
IPv6 Neighbor Discovery—Neighbor Solicitation Message
A and B can now exchange
packets on this link
Chapter 25
ICMPv6 Type = 136
Src = B
Dst = A
Data = link-layer address of B
Configuring IPv6 Neighbor Discovery
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