Configuration Guide User guide

984 FastIron Configuration Guide
53-1002494-02
Configuring IP parameters – Layer 3 Switches
For example, if Proxy ARP is enabled on a Layer 3 Switch connected to two subnets, 10.10.10.0/24
and 20.20.20.0/24, the Layer 3 Switch can respond to an ARP request from 10.10.10.69 for the
MAC address of the device with IP address 20.20.20.69. In standard ARP, a request from a device
in the 10.10.10.0/24 subnet cannot reach a device in the 20.20.20.0 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 5
Brocade(config-if-e1000-5)# ip proxy-arp enable
To again disable IP proxy ARP on an interface, enter the following command.
Brocade(config)# interface ethernet 5
Brocade(config-if-e1000-5)# ip proxy-arp disable
Syntax: [no] ip proxy-arp enable | disable
Enabling local proxy ARP
Brocade devices support Proxy Address Resolution Protocol (Proxy ARP), a feature that enables
router ports to respond to ARP requests for subnets it can reach. However, router ports will not
respond to ARP requests for IP addresses in the same subnet as the incoming ports, unless Local
Proxy ARP per IP interface is enabled. Local Proxy ARP enables router ports to reply to ARP
requests for IP addresses within the same subnet and to forward all traffic between hosts in the
subnet.