H3C Technologies H3C S5560 Series Switches - Manual (Page 170)

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Enabling ND proxy
About ND proxy
ND proxy enables a device to answer an NS message requesting the hardware address of a host on
another network. With ND proxy, hosts on different broadcast domains can communicate with each
other as they would on the same network.
ND proxy includes common ND proxy and local ND proxy.
• Common ND proxy
As shown in
Figure 59 , VLAN-interface 1 with IPv6 address 4:1::99/64 and VLAN-interface 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 59 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 common ND proxy on VLAN-interface 1 and VLAN-interface 2 of the
switch. The switch replies to the NS message from Host A, and forwards packets from other hosts
to Host B.
• Local ND proxy
As shown in
Figure 60 , both Host A and Host B belong to VLAN 2. However, they connect to
GigabitEthernet 1/0/3 and GigabitEthernet 1/0/1 respectively, which are isolated at Layer 2.
Figure 60 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.