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 in 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 83, GigabitEthernet 1/0/1 with IPv6 address 4:1::99/64 and GigabitEthernet 1/0/2 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 83: 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 GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 of the router. The router replies to the NS message from Host A, and forwards packets from other hosts to Host B.
Local ND proxy.
As shown in Figure 84, Host A belongs to VLAN 2 and Host B belongs to VLAN 3. Host A and Host B connect to GigabitEthernet 1/0/1 and GigabitEthernet 1/0/3, respectively.
Figure 84: 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 belong to different VLANs.
To solve this problem, enable local ND proxy on GigabitEthernet 1/0/2 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 connect to ports of the same device and the ports must be in different VLANs.
The two hosts connect to isolated Layer 2 ports in the same isolation group of a VLAN.
If super VLAN is used, the two hosts must belong to different sub VLANs.
If Private VLAN is used, the two hosts must belong to different secondary VLANs.
Configuration procedure
You can enable common ND proxy and local ND proxy in VLAN interface view, Layer 3 Ethernet interface view, or Layer 3 Ethernet subinterface view.
To enable common ND proxy:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Enable common ND proxy. | proxy-nd enable | By default, common ND proxy is disabled. |
To enable local ND proxy:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Enable local ND proxy. | local-proxy-nd enable | By default, local ND proxy is disabled. |