Cisco PIX 500 Series Configuration Manual page 198

Configuring IPv6
Figure 12-1
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.
You can configure the neighbor solicitation message interval and neighbor reachable time on a
per-interface basis. See the following topics for more information:
•
•
Configuring the Neighbor Solicitation Message Interval
To configure the interval between IPv6 neighbor solicitation retransmissions on an interface, enter the
following command:
hostname(config-if)# ipv6 nd ns-interval value
Valid values for the value argument range from 1000 to 3600000 milliseconds. The default value is 1000
milliseconds.
This setting is also sent in router advertisement messages.
Configuring the Neighbor Reachable Time
The neighbor reachable time enables detecting unavailable neighbors. Shorter configured times enable
detecting unavailable neighbors more quickly; however, shorter times consume more IPv6 network
bandwidth and processing resources in all IPv6 network devices. Very short configured times are not
recommended in normal IPv6 operation.
To configure the amount of time that a remote IPv6 node is considered reachable after a reachability
confirmation event has occurred, enter the following command:
hostname(config-if)# ipv6 nd reachable-time value
Cisco Security Appliance Command Line Configuration Guide
12-8
IPv6 Neighbor Discovery—Neighbor Solicitation Message
A and B can now exchange
packets on this link
Configuring the Neighbor Solicitation Message Interval, page 12-8
Configuring the Neighbor Reachable Time, page 12-8
ICMPv6 Type = 136
Src = B
Dst = A
Data = link-layer address of B
Chapter 12 Configuring IPv6
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