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Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring IPv6 Neighbor Discovery
Information About IPv6 Neighbor Discovery
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.
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.
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.
Duplicate Address Detection
During the stateless autoconfiguration process, Duplicate Address Detection verifies the uniqueness of
new unicast IPv6 addresses before the addresses are assigned to interfaces (the new addresses remain in
a tentative state while Duplicate Address Detection is performed). Duplicate Address Detection is
performed first on the new link-local address. When the link-local address is verified as unique, then
Duplicate Address Detection is performed all the other IPv6 unicast addresses on the interface.
Duplicate Address Detection is suspended on interfaces that are administratively down. While an
interface is administratively down, the unicast IPv6 addresses assigned to the interface are set to a
pending state. An interface returning to an administratively up state restarts Duplicate Address Detection
for all of the unicast IPv6 addresses on the interface.
When a duplicate address is identified, the state of the address is set to DUPLICATE, the address is not
used, and the following error message is generated:
%ASA-4-325002: Duplicate address
ipv6_address
/
MAC_address
on
interface
Summary of Contents for 5505 - ASA Firewall Edition Bundle
Page 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Page 61: ...P A R T 1 Getting Started with the ASA ...
Page 62: ......
Page 219: ...P A R T 2 Configuring High Availability and Scalability ...
Page 220: ......
Page 403: ...P A R T 2 Configuring Interfaces ...
Page 404: ......
Page 499: ...P A R T 2 Configuring Basic Settings ...
Page 500: ......
Page 533: ...P A R T 2 Configuring Objects and Access Lists ...
Page 534: ......
Page 601: ...P A R T 2 Configuring IP Routing ...
Page 602: ......
Page 745: ...P A R T 2 Configuring Network Address Translation ...
Page 746: ......
Page 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
Page 846: ......
Page 981: ...P A R T 2 Configuring Access Control ...
Page 982: ......
Page 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
Page 1062: ......
Page 1093: ...P A R T 2 Configuring Application Inspection ...
Page 1094: ......
Page 1191: ...P A R T 2 Configuring Unified Communications ...
Page 1192: ......
Page 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
Page 1334: ......
Page 1379: ...P A R T 2 Configuring Advanced Network Protection ...
Page 1380: ......
Page 1475: ...P A R T 2 Configuring Modules ...
Page 1476: ......
Page 1549: ...P A R T 2 Configuring VPN ...
Page 1550: ......
Page 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
Page 1966: ......
Page 2059: ...P A R T 2 System Administration ...
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Page 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Page 2099: ...P A R T 2 Reference ...
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