H3C Technologies H3C S7500E Series Switches - Manual (Page 23)

2-2
You can solve the problem by enabling proxy ARP on Switch. After that, Switch can reply to the ARP
request from Host A with the MAC address of Vlan-interface1, and forward packets sent from Host A to
Host B. In this case, Switch seems like a proxy of Host B.
A main advantage of proxy ARP is that it is added on a single Switch without disturbing routing tables
of other Switchs in the network. Proxy ARP acts as the gateway for IP hosts that are not configured
with a default gateway or do not have routing capability.
Local Proxy ARP
As shown in Figure 2-2 , Host A and Host B belong to VLAN 2, but are isolated at Layer 2. Host A
connects to GigabitEthernet2/0/3 while Host B connects to GigabitEthernet2/0/1. Enable local proxy
ARP on Switch A to allow Layer 3 communication between the two hosts.
Figure 2-2 Application environment of local proxy ARP
In one of the following cases, you need to enable local proxy ARP:
z Hosts connecting to different isolated Layer 2 ports in the same VLAN need to communicate at
Layer 3.
z If a super VLAN is configured, hosts in different sub VLANs of the super VLAN need to
communicate at Layer 3.
z If an isolate-user-VLAN is configured, hosts in different secondary VLANs of the
isolate-user-VLAN need to communicate at Layer 3.
Enabling Proxy ARP
Follow these steps to enable proxy ARP in VLAN interface view:
To do… Use the command… Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—
Enable proxy ARP proxy-arp enable
Required
Disabled by default.