IP routers and end nodes use ARP to determine the physical address of a node to which they want to send a packet. ARP is enabled by default. For one node to send a packet to another, the sending node must know the physical address of the destination node. The sending node, knowing only the destination IP address, first checks its ARP table for an entry that maps the destination IP address to the destination physical address. If the sending node finds the entry, it inserts the physical address into the packet and sends it. If the sending node does not find the entry in its ARP table, it broadcasts an ARP address request to the network. The destination node replies to the request with its own physical address, which the sending node uses to send the packet and adds to its ARP table for future use.
ARP Cache Update Timeout is the time period (in seconds) for an entry to be removed from the ARP table, if the entry has not been updated. This value can be set only for a primary interface, and if ARP Timer is enabled. ARP Timer is disabled by default. For best performance, set the ARP Cache Update timeout value to be greater than or equal to the value of ARP Cache Stale Timeout.
The valid range of values for ARP Cache Update Timeout is from 240 to 14400 seconds. Default value is 300 seconds.
ARP Cache Stale Timeout is the time period (in seconds) for an entry to be removed from the ARP table, if the entry has not been used for some time. If multihoming is enabled then we can set this value for a primary IP interface if they are grouped for load balancing and fault tolerance. In all other cases this can be set on all IP interfaces. ARP Timer is disabled by default. For best performance, set the ARP Cache Stale Timeout value to be lesser than or equal to the value of ARP Cache Update Timeout.
The valid range of values for ARP Cache Stale Timeout is from 240 to 14400 seconds. Default value is 300 seconds.
An IP router uses Proxy ARP when devices attached to one of its interfaces do not support IP subnetting and are unaware that they must go through the router to reach devices on other subnets of the same IP network. A router using Proxy ARP replies to ARP requests intended for devices on other subnets, but does so only if the device is reachable through the router. To determine whether the device is reachable, the router examines its own routing table.
Proxy ARP is required on the parent network of a stub subnet. The parent network has an IP address range that includes the IP address range of the stub subnet. The router responds to ARP requests sent on the parent network on behalf of devices on the stub subnet.
When both the parent and stub subnet are bound to IP interfaces, the router can detect the parent/stub subnet and automatically enable Proxy ARP for the appropriate interfaces. Even if Proxy ARP is not required, and not automatically enabled, you can still force it to be enabled with the Force Proxy ARP parameter.
You must enable Force Proxy ARP on each LAN interface on which the router must reply to ARP requests for destinations it can reach. Force Proxy ARP is disabled on each interface by default.
This section contains the following topics:
Load INETCFG and then select Bindings > an existing binding > Expert TCP/IP Bind Options > ARP Options.
Select Use of ARP > Disabled.
Press Esc until you are prompted to save your changes, and then select Yes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System > Yes.
Load INETCFG and then select Bindings > an existing binding > Expert TCP/IP Bind Options > ARP Options.
Select Force Proxy ARP > Enabled.
Press Esc until you are prompted to save your changes, and then select Yes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System > Yes.
Load INETCFG and then select Bindings > an existing binding > Expert TCP/IP Bind Options > ARP Options.
Select ARP Timer and then select Enabled.
Press Esc until you are prompted to save your changes, and then select Yes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System > Yes.
Load INETCFG and then select Bindings > an existing binding > Expert TCP/IP Bind Options > ARP Options.
Select ARP Cache Update Timeout and then enter a value in seconds.
Press Esc until you are prompted to save your changes, and then select Yes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System > Yes.
Load INETCFG and then select Bindings > an existing binding > Expert TCP/IP Bind Options > ARP Options.
Select ARP Cache Stale Timeout, then enter a value in seconds.
Press Esc until you are prompted to save your changes, then select Yes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System and select Yes to activate your changes.