Hi All, I am using the kea in HA mode with Hot-standby mode in my local lab testing before I use it in production and here is my failover config section: "hooks-libraries": [ { "library": "/var/lib/kea/hooks/libdhcp_ha.so", "parameters": {"high-availability": [{ "mode": "hot-standby", "heartbeat-delay": 10000, "trust-anchor": "", "multi-threading": { "http-dedicated-listener": true, "enable-multi-threading": true, "http-client-threads": 4, "http-listener-threads": 4 }, "max-response-delay": 60000, "cert-file": "", "this-server-name": "dhcp1", "max-ack-delay": 10000, "peers": [ { "role": "primary", "name": "dhcp1", "auto-failover": true, "url": "http://192.168.0.125:8001" }, { "role": "standby", "name": "dhcp2", "auto-failover": true, "url": "http://192.168.0.126:8001" } ], "key-file": "", "max-unacked-clients": 2 }]} }, The other part of the configuration is the same for both servers.
I am testing the case by stopping the primary appliance and see how the other peer reacts, and whether it can continue the service for the existing and new clients The problem I see is with max-unacked-clients parameter, I set the value to 2 and after stopping the primary I hit the command (ipconfig /renew)for a new client and I am unable to get leases so checked the following: Status-output ============ { "arguments": { "high-availability": [ { "ha-mode": "hot-standby", "ha-servers": { "local": { "role": "standby", "scopes": [], "state": "hot-standby" }, "remote": { "age": 327, "analyzed-packets": 145, "communication-interrupted": true, "connecting-clients": 3, "in-touch": true, "last-scopes": [ "dhcp1" ], "last-state": "unavailable", "role": "primary", "unacked-clients": 1, "unacked-clients-left": 2 } } } ], "multi-threading-enabled": true, "packet-queue-size": 29, "packet-queue-statistics": [ 1, 0.999997, 0.719168 ], "pid": 17707, "reload": 6093, "sockets": { "status": "ready" }, "thread-pool-size": 7, "uptime": 7488 }, "result": 0 } --> From the above status I have a few doubts, I set the max-unacked clients as 2 in my config but in the above status output it says "unacked-clients": 1, "unacked-clients-left": 2 Does that mean it is checking for 3 max-unacked clients to switch to partner-down state? If yes when can we call the client can be counted as unacked clients, I am not getting the leases for more than 5 laptops, and also I collected the tcpdump during that time to see the time elapsed seconds for discover packet, for few of the client it reached more than 20 seconds but still I don't see they get leases. The main reason I can think of here the status is not changed to partner-down and hence it is unable to give a lease but the reason behind that is max-unacked client, When I do the same with max-unacked client values as zero, I don't see any issue, and clients are able to get the lease because it switched to partner-down fastly When can we consider the client under max-unacked client ? I thought if the client sends a request and the server is unable to grant a lease then it can consider an unacked client but here when the client is sending the request to the stand-by server then we are seeing in the log as 2023-06-22 13:36:50.943 DEBUG [kea-dhcp4.ha-hooks/17707.140342512834304] HA_BUFFER4_RECEIVE_NOT_FOR_US [hwtype=1 08:6a:c5:82:de:a8], cid=[01:08:6a:c5:82:de:a8], tid=0xaaba6094: dropping query to be processed by another server and is not considered as un-ackedclient, so back to square when can we consider a client request as unacked ? Thanks in Advance Kraishak
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