F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Network Management Configuration Guide-6PW100

684
833BConfiguring the maximum number of attempts to send an NS
message for DAD
An interface sends an NS message for DAD after acquiring an IPv6 address. If the interface does not
receive a response within a specific time (determined by the ipv6 nd ns retrans-timer command), it
continues to send an NS message. If the interface still does not receive a response after the number of
sent attempts reaches the threshold (specified with the ipv6 nd dad attempts command), the acquired
address is considered usable.
To configure the attempts to send an NS message for DAD:
Ste
p
Command Remarks
957. Enter system view.
system-view N/A
958. Enter interface view.
interface interface-type
interface-number
N/A
959. Configure the number of
attempts to send an NS
message for DAD.
ipv6 nd dad attempts value
Optional.
1 by default. When the value argument is
set to 0, DAD is disabled.
834BEnabling ND proxy
ND proxy supports the NS and NA messages only.
1690BAbout ND proxy
If a host sends an NS message requesting the hardware address of another host that is isolated from the
sending host at Layer 2, the device in between must be able to forward the NS message to allow Layer
3 communication between the two hosts. This is achieved by ND proxy.
Depending on application scenarios, ND proxy falls into common ND proxy and local ND proxy.
Unless otherwise specified, ND proxy described in the following text refers to common ND proxy.
• ND proxy
As shown in
2880HFigure 361, GigabitEthernet 0/1 with IPv6 address 4:1::99/64 and GigabitEthernet
0/2 with IPv6 address 4:2::99/64 belong to different subnets. Host A and Host B reside on the
same network but in different broadcast domains.
Figure 361 Application environment of ND proxy
Because Host A's IPv6 address is on the same subnet as Host B's, Host A directly sends an NS
message to obtain Host B's MAC address. However, Host B cannot receive the NS message
because they belong to different broadcast domains.
To solve this problem, enable ND proxy on GigabitEthernet 0/1 and GigabitEthernet 0/2 of the
firewall. The firewall replies to the NS message from Host A, and forwards packets from other
hosts to Host B.