[Kea-users] Three Requests, Two Responses

[Doug Freed]

On 9/15/26 22:30, Elton, Norman N wrote:
> We have three routers relaying DHCP requests back to Kea. Looking at our 
> server logs for the DISCOVER message:
> 
> [kea-dhcp4.packets.111] DHCP4_PACKET_RECEIVED: DHCPDISCOVER (type 1) 
> received from 192.168.96.4 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.packets.222] DHCP4_PACKET_RECEIVED: DHCPDISCOVER (type 1) 
> received from 192.168.96.2 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.packets.333] DHCP4_PACKET_RECEIVED: DHCPDISCOVER (type 1) 
> received from 192.168.96.3 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.leases.111] DHCP4_LEASE_OFFER: lease 192.168.100.179 will be 
> offered
> [kea-dhcp4.packets.111] DHCP4_PACKET_SEND: trying to send packet 
> DHCPOFFER (type 2) from 192.168.10.155:67 to 192.168.96.4:67 on 
> interface bond0.10
> [kea-dhcp4.leases.444] DHCP4_LEASE_OFFER: lease 192.168.100.181 will be 
> offered
> [kea-dhcp4.packets.444] DHCP4_PACKET_SEND: trying to send packet 
> DHCPOFFER (type 2) from 192.168.10.155:67 to 192.168.96.3:67 on 
> interface bond0.10
> 
> We see three incoming packets from our three routers, but only two 
> outgoing OFFERs. Likewise, when the REQUESTs come in:
> 
> [kea-dhcp4.packets.333] DHCP4_PACKET_RECEIVED: DHCPREQUEST (type 3) 
> received from 192.168.96.2 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.packets.111] DHCP4_PACKET_RECEIVED: DHCPREQUEST (type 3) 
> received from 192.168.96.4 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.packets.444] DHCP4_PACKET_RECEIVED: DHCPREQUEST (type 3) 
> received from 192.168.96.3 to 192.168.10.155 on interface bond0.10
> [kea-dhcp4.leases.333] DHCP4_LEASE_ALLOC: lease 192.168.100.179 has been 
> allocated for 86400 seconds
> [kea-dhcp4.leases.333] DHCP4_LEASE_ALLOC: lease 192.168.100.179 has been 
> allocated for 86400 seconds
> [kea-dhcp4.packets.111] DHCP4_PACKET_SEND: trying to send packet DHCPACK 
> (type 5) from 192.168.10.155:67 to 192.168.96.2:67 on interface bond0.10
> [kea-dhcp4.packets.444] DHCP4_PACKET_SEND: trying to send packet DHCPACK 
> (type 5) from 192.168.10.155:67 to 192.168.96.3:67 on interface bond0.10
> 
> Only two outgoing ACKs. Any reason why Kea is not responding to all 
> three requests?
> 
> Thanks!
> 
> Norman
> 

This is deduplication of incoming packets.  If additional packets come 
in while Kea is still processing a packet for the same client, only the 
next packet is also processed, and any further packets are dropped until 
the first packet is finished processing.  The next packet for the client 
is also only processed once the first packet is finished processing.  If 
you enable debug logging with level 15, you'll see either 
DHCP4_PACKET_DROP_0011 or DHCP4_PACKET_DROP_0012 depending on which 
exact point in the code Kea decides to drop the excess packets.

-Doug