Enabling local proxy arp, Creating static arp entries – Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 User Manual

Page 57

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Brocade ICX 6650 Layer 3 Routing Configuration Guide

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Configuring IP parameters – Layer 3 Switches

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.

When Local Proxy ARP is enabled on a router port, the port will respond to ARP requests for IP
addresses within the same subnet, if it has ARP entries for the destination IP addresses in the ARP
cache. If it does not have ARP entries for the IP addresses, the port will attempt to resolve them by
broadcasting its own ARP requests.

Local Proxy ARP is disabled by default. To use Local Proxy ARP, Proxy ARP (ip proxy-arp command)
must be enabled globally on the Brocade device. You can enter the CLI command to enable Local
Proxy ARP even though Proxy ARP is not enabled, however, the configuration will not take effect
until you enable Proxy ARP.

Use the show run command to view the ports on which Local Proxy ARP is enabled.

To enable Local Proxy ARP, enter commands such as the following.

Brocade(config)# interface ethernet 1/1/4

Brocade(config-if-e10000-1/1/4)# ip local-proxy-arp

Syntax: [no] ip local-proxy-arp

Use the no form of the command to disable Local Proxy ARP.

Creating static ARP entries

Brocade Layer 3 Switches have a static ARP table, in addition to the regular ARP cache. The static
ARP table contains entries that you configure.

Static entries are useful in cases where you want to pre-configure an entry for a device that is not
connected to the Layer 3 Switch, or you want to prevent a particular entry from aging out. The
software removes a dynamic entry from the ARP cache if the ARP aging interval expires before the
entry is refreshed. Static entries do not age out, regardless of whether the Brocade device receives
an ARP request from the device that has the entry address.

NOTE

You cannot create static ARP entries on a Layer 2 Switch.

The maximum number of static ARP entries you can configure depends on the software version
running on the device. Refer to

“Changing the maximum number of entries the static ARP table can

hold”

on page 40.

To display the ARP cache and static ARP table, refer to the following:

•

To display the ARP table, refer to

“Displaying the ARP cache”

on page 118.

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