H3C Technologies H3C S12500 Series Switches - Manual (Page 164)

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Step Command Remarks
6. Configure the maximum number of
ND snooping entries the interface
can learn.
ipv6 nd snooping max-learning-num
number
Optional.
By default, the number of
ND snooping entries an
interface can learn is
unlimited.
Enabling ND proxy
ND proxy supports the NS and NA messages only.
About 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 includes common ND proxy and local ND proxy.
• Common ND proxy
As shown in
Figure 62 , GigabitEthernet 3/0/1 with IPv6 address 4:1::99/64 and
GigabitEthernet 3/0/2 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 62 Application environment of common 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 3/0/1 and GigabitEthernet
3/0/2 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 63 , VLAN 10 is a super VLAN whose sub VLANs are VLAN 2 and VLAN 3.
Host A and Host B belong to VLAN 2 and VLAN 3 respectively, and they connect to
GigabitEthernet 3/0/3 and GigabitEthernet 3/0/1 respectively, which are isolated at Layer 2.