Brocade BigIron RX Series Configuration Guide - Manual (Page 235)

BigIron RX Series Configuration Guide 157
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The IP packet flow
7
ARP cache table
The Address Resolution Protocol (ARP) is supported on the device. Refer to “IP fragmentation
protection” on page 188.
The ARP cache contains entries that map IP addresses to MAC addresses. Generally, the entries
are for devices that are directly attached to the device or virtual interfaces.
An exception is an ARP entry for an interface-based static IP route that goes to a destination that is
one or more router hops away. For this type of entry, the MAC address is either the destination
device’s MAC address or the MAC address of the router interface that answered an ARP request on
behalf of the device, using proxy ARP.
The ARP cache can contain dynamic (learned) entries and static (user-configured) entries. The
software places a dynamic entry in the ARP cache when the device learns a device’s MAC address
from an ARP request or ARP reply from the device.
The software can learn an entry when the device receives an ARP request from another IP
forwarding device or an ARP reply. Here is an example of a dynamic entry.
Each entry contains the destination device’s IP address and MAC address.
Static ARP table
In addition to the ARP cache, the device has a static ARP table.
Entries in the static ARP table are user-configured. You can add entries to the static ARP table
regardless of whether the device the entry is for is connected to the device.
The software places an entry from the static ARP table into the ARP cache when the entry’s
interface comes up.
Here is an example of a static ARP entry.
Index IP Address MAC Address Port
1 207.95.6.111 0800.093b.d210 1/1
Each entry lists the information you specified when you created the entry.
To display ARP entries, refer to the following:
• “Displaying the ARP cache” on page 226
• “Displaying the static ARP table” on page 227
To configure other ARP parameters, refer to “IP fragmentation protection” on page 188.
To increase the size of the ARP cache and static ARP table, see the following:
• For dynamic entries, refer to “Displaying and modifying system parameter default settings” on
page 133. The ip-arp parameter controls the ARP cache size.
• For static entries, refer to “Changing the maximum number of entries the static ARP table can
hold” on page 194. The ip-static-arp parameter controls the static ARP table size.
IP Address MAC Address Type Age Port
1 207.95.6.102 0800.5afc.ea21 Dynamic 0 6