Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 56)

38 Brocade ICX 6650 Layer 3 Routing Configuration Guide
53-1002603-01
Configuring IP parameters – Layer 3 Switches
Enabling proxy ARP
Proxy ARP allows a Layer 3 Switch to answer ARP requests from devices on one network on behalf
of devices in another network. Since ARP requests are MAC-layer broadcasts, they reach only the
devices that are directly connected to the sender of the ARP request. Thus, ARP requests do not
cross routers.
For example, if Proxy ARP is enabled on a Layer 3 Switch connected to two subnets,
192.168.10.0/24 and 192.168.20.0/24, the Layer 3 Switch can respond to an ARP request from
192.168.10.69 for the MAC address of the device with IP address 192.168.20.69. In standard ARP,
a request from a device in the 192.168.10.0/24 subnet cannot reach a device in the 192.168.20.0
subnet if the subnets are on different network cables, and thus is not answered.
NOTE
An ARP request from one subnet can reach another subnet when both subnets are on the same
physical segment (Ethernet cable), because MAC-layer broadcasts reach all the devices on the
segment.
Proxy ARP is disabled by default on Brocade Layer 3 Switches. This feature is not supported on
Brocade Layer 2 Switches.
You can enable proxy ARP at the Interface level, as well as at the Global CONFIG level, of the CLI.
NOTE
Configuring proxy ARP at the Interface level overrides the global configuration.
Enabling proxy ARP globally
To enable IP proxy ARP on a global basis, enter the ip proxy-arp command.
Brocade(config)# ip proxy-arp
To again disable IP proxy ARP on a global basis, enter the no ip proxy-arp command.
Brocade(config)# no ip proxy-arp
Syntax: [no] ip proxy-arp
Enabling IP ARP on an interface
NOTE
Configuring proxy ARP at the Interface level overrides the global configuration.
To enable IP proxy ARP on an interface, enter the following commands.
Brocade(config)# interface ethernet 1/1/5
Brocade(config-if-e10000-1/1/5)# ip proxy-arp enable
To again disable IP proxy ARP on an interface, enter the following command.
Brocade(config)# interface ethernet 1/1/5
Brocade(config-if-e10000-1/1/5)# ip proxy-arp disable
Syntax: [no] ip proxy-arp enable | disable