Local Proxy Arp; Enabling Proxy Arp - 3Com 4500G Family Configuration Manual

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-interface 1, and forward packets sent from Host A
to Host B. In this case, Switch seems to be a proxy of Host B.
A main advantage of proxy ARP is that it is added on a single router without disturbing routing tables of
other routers 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
connects to GigabitEthernet 1/0/3 while Host B connects to GigabitEthernet 1/0/1. Enable local proxy
ARP on Switch Ato allow Layer 3 communication between the two hosts.
Figure 2-2 Application environment of local proxy ARP
192.168.10.100/16
GE1/0/3
Host A
192.168.10.99/16
In one of the following cases, you need to enable local proxy ARP:
Hosts connecting to different isolated Layer 2 ports in the same VLAN need to communicate at
Layer 3.
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...
Enter system view
Enter interface view
Enable proxy ARP
Follow these steps to enable local proxy ARP in VLAN interface view:
To do...
Enter system view
Enter interface view
2-2, Host A and Host B belong to VLAN 2, but are isolated at Layer 2. Host A
Switch A
VLAN 2
Vlan-int2
port-isolate group
GE1/0/2
GE1/0/1
Switch B
192.168.10.200/16
Use the command...
system-view
interface interface-type interface-number
proxy-arp enable
Use the command...
system-view
interface interface-type interface-number
VLAN 2
Host B
2-2
Remarks
—
—
Required
Disabled by default.
Remarks
—
—