Configuring A Dual Ip Stack On An Interface; Configuring Ipv6 Duplicate Address Detection - Cisco 7604 Configuration Manual

Configuring a Dual IP Stack on an Interface

Configuring a Dual IP Stack on an Interface
FWSM supports the configuration of both IPv6 and IPv4 on an interface. You do not need to enter any
special commands to do so; simply enter the IPv4 configuration commands and IPv6 configuration
commands as you normally would. Make sure you configure the default route for both IPv4 and IPv6.

Configuring IPv6 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 and the address is
not used. If the duplicate address is the link-local address of the interface, the processing of IPv6 packets
is disabled on the interface and an error message is issued. If the duplicate address is a global address of
the interface, the address is not used and an error message is issued. However, all configuration
commands associated with the duplicate address remain as configured while the state of the address is
set to DUPLICATE.
If the link-local address for an interface changes, duplicate address detection is performed on the new
link-local address and all of the other IPv6 address associated with the interface are regenerated
(duplicate address detection is performed only on the new link-local address).
FWSM uses neighbor solicitation messages to perform duplicate address detection. By default, the
number of times an interface performs duplicate address detection is 1.
To change the number of duplicate address detection attempts, enter the following command:
hostname(config-if)# ipv6 nd dad attempts value
The value argument can be any value from 0 to 600. Setting the value argument to 0 disables duplicate
address detection on the interface.
When you configure an interface to send out more than one duplicate address detection attempt, you can
also use the ipv6 nd ns-interval command to configure the interval at which the neighbor solicitation
messages are sent out. By default, they are sent out once every 1000 milliseconds.
To change the neighbor solicitation message interval, enter the following command:
hostname(config-if)# ipv6 nd ns-interval value
The value argument can be from 1000 to 3600000 milliseconds.
Changing this value changes it for all neighbor solicitation messages sent out on the interface, not just
Note
those used for duplicate address detection.
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
10-4
Chapter 10 Configuring IPv6
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