ARP cache renewal

Discussion in 'Server Networking' started by david, Aug 14, 2008.

  1. david

    david Guest

    I have hundreds of network devices I am testing, all on the same IP address.
    Each time I change devices, I have to wait 2 minutes for the ARP cache to
    timeout. If I attempt any activity within that time it fails, but the ARP
    cache restarts the timer.

    The device does Gratuitous ARP at power up, but Windows is ignoring that.

    I do not wish to clear the ARP cache from the command line every time: my
    hands are full. Even waiting 3 minutes is not a bad as that. I am looking
    for a better way.

    Is there any way I can (1) Change the ARP timeout interval or (2) Get
    Windows to recognise Gratuitous ARP?

    (david)
     
    david, Aug 14, 2008
    #1
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  2. david

    Olivier C. Guest

    Hello David ,

    Here's the solution :

    How to change the ARP timeout interval ? :


    See Option DHCP 35 in DHCP.(RFC 2132)
    http://www.faqs.org/rfcs/rfc2132.html


    Get Windows to recognise Gratuitous ARP?

    http://www.windowsreference.com/win...sts-in-windows-server-2008-and-windows-vista/

    http://wiki.wireshark.org/Gratuitous_ARP

    Client-Side Conflict Detection
    With the evolution of smarter client operating systems such as Windows 2000
    and
    Windows XP, conflict detection has been integrated into the client side of
    the DHCP
    leasing process. A process called gratuitous arp defines the steps by which
    a client attempts to
    determine if its offered IP lease is already in use on its network
    segment.The DHCP client
    sends a gratuitous arp request on the local subnet for the offered IP
    address. If it receives a
    positive reply, it knows the address is already in use and sends a
    DHCPDECLINE message
    back to the DHCP server.Then the client requests another address.


    Regards,


    Olivier C.

    Microsoft Customer Service and Support.


    ####################################################
     
    Olivier C., Aug 19, 2008
    #2
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  3. david

    david Guest

    Thank You.

    In the end I used the registry settings:

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
    "ArpCacheMinReferencedLife"=dword:0000001e
    "ArpCacheLife"=dword:0000001e

    to set the ARP timeout interval to 30 seconds (the defaults in XP are 120 &
    180)

    Vista does not use these entries, but Vista defaults to 30 & 45 seconds
    anyway.

    (david)
     
    david, Oct 14, 2008
    #3
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