1.2.4.1.2 Address Resolution Protocol (ARP) Configurations

ARP Specific User Configurations

  • Number of Cache Entries:

    • Default number of entries per interface.
    • Default value 5
    • Symbol TCPIP_ARP_CACHE_ENTRIES

  • Enable ARP Commands:

    • Enable the ARP TCP/IP Console Commands
    • Default value: false
    • Symbol: TCPIP_ARP_COMMANDS_ENABLE

  • Delete Old Cache:

    • On initialization, delete the old cache if still in place
    • Else do not re-initialize
    • Default value: 1
    • Symbol TCPIP_ARP_CACHE_DELETE_OLD

  • Time-Out for removal of Solved Entry (in sec):

    • Timeout for a solved entry in the cache.
    • The entry will be removed if the tmo elapsed and the entry has not been referenced again
    • Value is in seconds
    • Default value: (20 * 60)
    • Symbol TCPIP_ARP_CACHE_SOLVED_ENTRY_TMO

  • Time-Out to solve Pending Cache Entry (in sec):

    • Timeout for a cache entry pending to be solved
    • The entry will be removed if the tmo elapsed and the entry has not been solved.
    • A solved entry moves to the solved entries timeout.
    • Value is in seconds
    • Default value: (1 * 60)
    • Symbol TCPIP_ARP_CACHE_PENDING_ENTRY_TMO

  • Time-Out for Resending an ARP Request for Pending Entry (in sec):

    • Timeout for resending an ARP request for a pending entry
    • In order to prevent the ARP flooding the standard recommends it to be greater than 1 sec.
    • It should be less than TCPIP_ARP_CACHE_PENDING_ENTRY_TMO
    • Value is in seconds
    • Default value: 2
    • Symbol TCPIP_ARP_CACHE_PENDING_RETRY_TMO

  • Number of Retries for Resolving an Entry:

    • Number of ARP requests generated for resolving an entry.
    • Default value: 3
    • Symbol TCPIP_ARP_CACHE_ENTRY_RETRIES

  • Number of Retries for Gratuitous ARP Request:

    • Number of ARP requests generated when sending a gratuitous ARP probe.
    • Default value: 1
    • Symbol TCPIP_ARP_GRATUITOUS_PROBE_COUNT

  • Purge Threshold Percentage:

    • Default purge threshold, percentage
    • Once the number of resolved entries in the cache gets beyond the threshold some resolved entries will be purged.
    • Default value: 75
    • Symbol TCPIP_ARP_CACHE_PURGE_THRESHOLD

  • Number of Entries to Delete Once the Threshold is Reached:

    • The number of entries to delete, once the threshold is reached.
    • Default value: 3
    • Symbol TCPIP_ARP_CACHE_PURGE_QUANTA

  • Maximum Percentage of Permanent Entries Allowed in Cache:

    • Maximum percentage of permanent entries in the cache.
    • Note that since permanent entries cannot be removed they tend to degrade the efficiency of the cache look up.
    • Default value: 50
    • Symbol TCPIP_ARP_CACHE_PERMANENT_QUOTA

  • Alias Interfaces Share One Cache:

    • ARP caches configuration for aliases.
    • If this symbol is true, then the alias interfaces share the cache with the primary interface.
    • Otherwise each interface uses its own cache.
    • Default value should be 1 if the alias interfaces are in the same network with the primary interface
    • Symbol TCPIP_ARP_PRIMARY_CACHE_ONLY

  • ARP Task Rate (in msec):

    • ARP task processing rate, in milliseconds.
    • The ARP module will process a timer event with this rate for maintaining its own queues, processing timeouts, etc.
    • Choose it so that the other ARP_CACHE_xxx_TMO are multiple of this
    • The lower the rate (higher the frequency) the higher the module priority and higher module performance can be obtained
    • The value cannot be lower than the TCPIP_STACK_TICK_RATE.
    • Default value: 2000
    • Symbol TCPIP_ARP_TASK_PROCESS_RATE