Multiple ACK Issue

[Leigh Porter]

I see a similar issue with a similar config, however the duplicate ACK is not on the initial request but for lease renewals.

I've not bothered investigating so far as it seemed to do no harm for now..

--
Leigh

From: dhcp-users-bounces+leigh.porter=ukbroadband.com at lists.isc.org [mailto:dhcp-users-bounces+leigh.porter=ukbroadband.com at lists.isc.org] On Behalf Of Joey D.
Sent: 02 April 2014 17:04
To: dhcp-users at lists.isc.org
Subject: Multiple ACK Issue

 Below is a diagram of what we witness is happening in the event of a device reboot of a previously connected device (meaning the device is already established in the leases db on both servers), as well as our failover config.  Is there a configuration directive that can be used which mandates that only the server sending the offer can send the ACK? (much like what is done when allocating a fresh lease like in sec 3.2 in the rfc).   I can detail a bit more as to the environment layout if necessary, but I'm hoping there is an option I'm simply overlooking.


                Server A        Client          Server B

                  v               v              v
                  |               |              |
                  |     Begins initialization    |
                  |               |              |
                  | _____________/|\____________ |
                  |/DHCPDISCOVER  | DHCPDISCOVER\|
                  |               |              |
                  |               |              |
                  |               |  ___________/|
                  |               | /DHCPOFFER   |
                  |               |/             |
                  |     Selects configuration    |
                  |               |              |
                  | _____________/|\____________ |
                  |/ DHCPREQUEST  |  DHCPREQUEST\|
                  |               |              |
                  |               |              |
                  |               |              |
                  |\_____________ | ____________/|
                  |      DHCPACK \|/ DHCPACK     |
                  |               |              |
                  |    Initialization complete   |



SERVER A:
stash-agent-options true;

failover peer "iah-kcm" {
      primary;
      address x.x.1.248;
      port 647;
      peer address x.x.2.248;
      peer port 647;
      auto-partner-down 121;
      max-response-delay 120;
      max-unacked-updates 10;
      load balance max seconds 5;
      mclt 3600;
      split 128;

}
server-identifier x.x.1.248;
ping-check false;


SERVER B:
stash-agent-options true;

failover peer "iah-kcm" {

      secondary;
      address x.x.2.248;
      port 647;
      peer address x.x.1.248;
      peer port 647;
      auto-partner-down 121;
      max-response-delay 120;
      max-unacked-updates 10;
      load balance max seconds 5;
}
server-identifier x.x.2.248;
ping-check false;


- Joey D.

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