Configuring IP IP Forwarding
OmniSwitch AOS Release 8 Network Configuration Guide December 2017 page 15-15
Clearing a Dynamic Entry from the ARP Table
Dynamic entries can be cleared using the ip distributed-arp admin-state command. This command
clears all dynamic entries. Clear the permanent entries using the no arp command.
Use the show arp command to display the table and verify that the table was cleared.
Local Proxy ARP
The Local Proxy ARP feature is an extension of the Proxy ARP feature, but is enabled on an IP interface
and applies to the VLAN bound to that interface. When Local Proxy ARP is enabled, all ARP requests
received on VLAN member ports are answered with the MAC address of the IP interface that has Local
Proxy ARP enabled. In essence, all VLAN traffic is now routed within the VLAN instead of bridged.
This feature is intended for use with port mapping applications where VLANs are one-port associations.
This allows hosts on the port mapping device to communicate through the router. ARP packets are still
bridged across multiple ports.
Local Proxy ARP takes precedence over any switch-wide Proxy ARP or ARP function. In addition, it is
not necessary to configure Proxy ARP to use Local Proxy ARP. The two features are independent of each
other.
By default, Local Proxy ARP is disabled when an IP interface is created. To enable this feature, use the ip
interface command. For example:
-> ip interface Accounting local-proxy-arp
When Local Proxy ARP is enabled for any one IP router interface associated with a VLAN, the feature is
applied to the entire VLAN. It is not necessary to enable it for each interface. However, if the IP interface
that has the Local Proxy ARP feature enabled is moved to another VLAN, Local Proxy ARP is enabled
for the new VLAN and must be enabled on another interface for the old VLAN.
ARP Filtering
ARP filtering is used to determine whether the switch responds to ARP requests that contain a specific IP
address. ARP filtering is used in conjunction with the Local Proxy ARP application; however, it is
available for use on its own or with other applications.
By default, no ARP filters exist in the switch configuration. When there are no filters present, all ARP
packets are processed, unless they are blocked or redirected by some other feature.
Use the arp filter command to specify the following parameter values required to create an ARP filter:
• An IP address (for example, 193.204.173.21) used to determine whether an ARP packet is filtered.
• An IP mask (for example, 255.0.0.0) used to identify which part of the ARP packet IP address is
compared to the filter IP address.
• An optional VLAN ID to specify that the filter is only applied to ARP packets from that VLAN.
Note. Dynamic entries remain in the ARP table until they time out. If the switch does not receive data from
a host for this user-specified time, the entry is removed from the table. If another packet is received from
this host, the switch goes through the discovery process again to add the entry to the table. The switch uses
the MAC Address table time-out value as the ARP time-out value. Use the mac-learning aging-time
command to set the time-out value.
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