R2511-HP MSR Router Series Layer 3 - IP Services Configuration Guide(V5)

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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
1. Enter system view.
system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. 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.
Enabling local ND proxy
ND proxy supports only the NS and NA messages.
About local 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 local ND proxy.
As shown in Figure 110, both Ho
st A and Host B belong to VLAN 2, but they connect to Ethernet 1/3 and
Ethernet 1/1 respectively, which are isolated at Layer 2.
Figure 110 Application environment of local 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 are
isolated at Layer 2.
To solve this problem, enable local ND proxy on Ethernet 1/2 of the router so that the router can forward
messages between Host A and Host B.
Local ND proxy implements Layer 3 communication for two hosts in the following cases:
• The two hosts must connect to different isolated Layer 2 ports of a VLAN.