[Kea-users] Load-Balancing Network issue between Relay and Kea

[Frey, Rick E]

I’ve only used Kea in Hot-Standby configuration so I don’t have direct experience with Load-Balancing config but failover is similar.

Docs indicate that your Kea 2 host should mark Kea 1 as “partner-down” state if number of un-ack’d clients is exceeded ( 1 in your configuration ).  In order for Kea 2 to detect the un-ack’d requests (that should be handled by Kea 1), the secs (Seconds elaspsed) field must exceed max-ack-delay value ( 10 seconds in your case ).

Do your DHCP request include the secs field and exceed 10 seconds in your tests?
Does “Kea 2” show any unacked-clients during your test/network disruption?
(status-get cmd will show unacked-clients as well as current state).


From: Kea-users <kea-users-bounces at lists.isc.org> on behalf of Mathias Aichinger <mathias.aichinger at easysol.at>
Date: Sunday, January 1, 2023 at 6:11 PM
To: kea-users at lists.isc.org <kea-users at lists.isc.org>
Subject: [Kea-users] Load-Balancing Network issue between Relay and Kea
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Hi,

I currently playing around with the HA and load balancing and I one question appeared:

Scenario:

Multiple DHCP-Relays at different sites with both KEA-Servers as DHCP-Servers. Both servers are available and the load balancing shifts the requests between the two servers.

Incident: Because of a network issue Kea 1 is not available from the clients. The network connection between Kea 1 and Kea 2 still works, so no partner-down state.

Expected behaviour: Kea 2 sees the unacked clients of Kea 1 and sets Kea 1 in partner-down state and handles all requests.

Experienced behaviour: Kea 2 still reports HA_BUFFER4_RECEIVE_NOT_FOR_US and does not handle the requests

Is there a misunderstanding or configuration mistake on my side?

{
         "library": "/usr/local/lib/kea//hooks/libdhcp_ha.so",
         "parameters": {
           "high-availability": [
             {
               "this-server-name": "server2",
               "mode": "load-balancing",
               "heartbeat-delay": 10000,
               "max-response-delay": 60000,
               "max-ack-delay": 10000,
               "max-unacked-clients": 1,
               "delayed-updates-limit": 100,
               "peers": [
                 {
                   "name": "server1",
                   "url": "http://192.168.248.1:8080/<https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2F192.168.248.1%3A8080%2F&data=05%7C01%7Crick.frey%40windstream.com%7C03e10dc7ee6b44bf8b9508daec55f3c2%7C2567b4c1b0ed40f5aee358d7c5f3e2b2%7C0%7C0%7C638082151158318762%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=jpDZewyvQFVTEdrLMhapcgClTcerL8gfvZKK8qYeQhc%3D&reserved=0>",
                   "role": "primary",
                   "auto-failover": true
                 },
                 {
                   "name": "server2",
                   "url": "http://192.168.248.2:8080/<https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2F192.168.248.2%3A8080%2F&data=05%7C01%7Crick.frey%40windstream.com%7C03e10dc7ee6b44bf8b9508daec55f3c2%7C2567b4c1b0ed40f5aee358d7c5f3e2b2%7C0%7C0%7C638082151158318762%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Ck5xI%2B4nn6huIG9KIG2VfLItqyHWlZCbrAgKdx%2F7Nxs%3D&reserved=0>",
                   "role": "secondary",
                   "auto-failover": true
                 }
               ]
             }
           ]
         }
       }

Thank you,

Mathias



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