[Kea-users] Dropping the packets in load balancing

Wed May 17 10:32:45 UTC 2023

Hi Kraishak,

This also appears to be designed behavior.  I found this:

waiting - each started server instance enters this state. A backup
server transitions directly from this state to the backup state. An
active server sends a heartbeat to its partner to check its state; if
the partner appears to be unavailable, the server transitions to the
partner-down state. If the partner is available, the server
transitions to the syncing or ready state, depending on the setting of
the sync-leases configuration parameter. If both servers appear to be
in the waiting state (concurrent startup), the primary server
transitions to the next state first. The secondary or standby server
remains in the waiting state until the primary transitions to the
ready state.

under: https://kea.readthedocs.io/en/kea-2.2.0/arm/hooks.html#server-states

So, TLDR, the servers enter waiting state when they start.  If the
partner server does not appear, then the sole running server proceeds
directly to partner-down.

Thank you,

Darren Ankney

On Tue, May 16, 2023 at 10:40 AM Kraishak Mahtha <kraishak.edu at gmail.com> wrote:
>
> Hi Peter,
>
> but only one
> HA_COMMUNICATION_INTERRUPTED_CLIENT4_UNACKED message.
>
> 2023-05-15 16:07:30.127 INFO  [kea-dhcp4.ha-hooks/32411.139751579436800] HA_COMMUNICATION_INTERRUPTED_CLIENT4_UNACKED [hwtype=1 34:98:b5:dc:1f:99], cid=[no info], tid=0x4be21c7f: partner server failed to respond, 1 clients unacked so far, 13 clients left before transitioning to the partner-down state
> -----> ok, but this seems to not apply to my first test case
> (i.e Where I have no active leases on both servers and started only one server after 6 iterations it went to partner down)
> 2023-05-15 15:18:07.006 INFO  [kea-dhcp4.ha-hooks/27021.140594439104704] HA_INIT_OK loading High Availability hooks library successful.
>
> Logs of my first test case:
> =====================
> 2023-05-15 15:18:07.014 INFO  [kea-dhcp4.ha-hooks/27021.140594439104704] HA_LOCAL_DHCP_DISABLE local DHCP service is disabled while the dhcp1 is in the WAITING state
> 2023-05-15 15:18:07.014 INFO  [kea-dhcp4.ha-hooks/27021.140594439104704] HA_SERVICE_STARTED started high availability service in load-balancing mode as primary server
> 2023-05-15 15:18:17.027 WARN  [kea-dhcp4.ha-hooks/27021.140594206709504] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:18:27.899 WARN  [kea-dhcp4.ha-hooks/27021.140594198316800] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:18:37.909 WARN  [kea-dhcp4.ha-hooks/27021.140594215102208] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:18:47.919 WARN  [kea-dhcp4.ha-hooks/27021.140594223494912] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:18:58.730 WARN  [kea-dhcp4.ha-hooks/27021.140594198316800] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:19:09.245 WARN  [kea-dhcp4.ha-hooks/27021.140594223494912] HA_HEARTBEAT_COMMUNICATIONS_FAILED failed to send heartbeat to dhcp2 (http://192.168.0.126:8001): Connection refused
> 2023-05-15 15:19:09.245 WARN  [kea-dhcp4.ha-hooks/27021.140594223494912] HA_COMMUNICATION_INTERRUPTED communication with dhcp2 is interrupted
> 2023-05-15 15:19:09.245 INFO  [kea-dhcp4.ha-hooks/27021.140594223494912] HA_STATE_TRANSITION server transitions from WAITING to PARTNER-DOWN state, partner state is UNDEFINED
>
> Can you guide me on how this worked?
>
> Thanks
> Kraishak
>
>
> On Tue, May 16, 2023 at 2:31 PM Peter Davies <peterd at isc.org> wrote:
>>
>> Hi Kraishak,
>>    Looking at your log file, it appears that "Server A" only saw one unacked
>> client, so it didn't transform to a partner-down state. I see several
>> HA_COMMUNICATION_INTERRUPTED_CLIENT4 messages
>> but only one
>> HA_COMMUNICATION_INTERRUPTED_CLIENT4_UNACKED message.
>>
>> 2023-05-15 16:07:30.127 INFO  [kea-dhcp4.ha-hooks/32411.139751579436800] HA_COMMUNICATION_INTERRUPTED_CLIENT4_UNACKED [hwtype=1 34:98:b5:dc:1f:99], cid=[no info], tid=0x4be21c7f: partner server failed to respond, 1 clients unacked so far, 13 clients left before transitioning to the partner-down state
>>
>> Your configuration contains the following statement:
>>    "max-unacked-clients": 13
>> The "max-ack-delay" parameter has a default value of 10000 ms.
>> I suggest you check that your traffic generator correctly increments the "secs"
>> field and to modify your HA settings appropriately.
>>
>> From the Kea ARM:
>>
>> HA_COMMUNICATION_INTERRUPTED_CLIENT4
>> %1: new client attempting to get a lease from the partner
>> This informational message is issued when the surviving server observes a DHCP
>> packet sent to the partner with which the communication is interrupted. The
>> the client whose packet is observed is not yet considered “unacked” because the
>> secs field value does not exceed the configured threshold specified with
>> max-ack-delay.
>>
>> HA_COMMUNICATION_INTERRUPTED_CLIENT4_UNACKED
>> %1: partner server failed to respond, %2 clients unacked so far, %3 clients left before transitioning to the partner-down state
>> This informational message is issued when the surviving server determines that
>> its partner failed to respond to the DHCP query and that this client is considered
>> to not be served by the partner. The surviving server counts such clients, and if
>> the number of such clients exceeds the max-unacked-clients threshold, the server
>> will transition to the partner-down state. The first argument contains client
>> identification information. The second argument specifies the number of clients
>> to which the server has failed to respond. The third argument specifies the number
>> of additional clients, which, if not provisioned, will cause the server to transition
>> to the partner-down state.
>>
>> Kind Regards Peter
>
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