DHCP failover doesn't receive DHCP requests in secondary server

[Leroy Tennison]

(Robert) you didn't provide a lot of detail so the answers are probably going to be general.  A couple of additional ideas come to mind but, without specifics, it's hard to troubleshoot.  Is a firewall somewhere in the path blocking requests?  Has the server been configured to listen on a specific (possibly wrong) interface rather than all interfaces?


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________________________________________
From: dhcp-users <dhcp-users-bounces at lists.isc.org> on behalf of perl-list <perl-list at network1.net>
Sent: Wednesday, August 15, 2018 10:38 AM
To: Users of ISC DHCP
Subject: [EXTERNAL] Re: DHCP failover doesn't receive DHCP requests in secondary server

The problem isn't with the secondary server.  The DHCP packets must always go to both servers.  If the packets are relayed from a relay agent, then the relay agent must be configured to send to both of the DHCP servers (On a Cisco router, that would involve having ip helper-address listed twice, for example).

If no relay, then the DHCP servers must both be on the same LAN with the clients.

When both of the primary and secondary servers are running, you should see logs of the DHCP packets in both servers logs.

----- Original Message -----
> From: "Roberto Carna" <robertocarna36 at gmail.com>
> To: "Users of ISC DHCP" <dhcp-users at lists.isc.org>
> Sent: Wednesday, August 15, 2018 11:06:08 AM
> Subject: DHCP failover doesn't receive DHCP requests in secondary server

> Dear people,

> I´ve implemented a failover scheme with ISC-DHCP-SERVER in two
> different servers, with the same version of the package and OS.

> Everything seems to be OK, but when a execute "service isc-dhcp-server
> stop" in the primary server, in the secondary server I can see:

> Aug 15 11:52:01 dhcp2 dhcpd[5839]: peer dhcp-failover: disconnected
> Aug 15 11:52:01 dhcp2 dhcpd[5839]: failover peer dhcp-failover: I move
> from normal to communications-interrupted

> what is correct, but after that the secondary server doesnt' receive
> any DHCPREQUEST packet from clients.

> So, my faoilover scheme doesn't work, because if primary server goes
> down, the secondary server doesn't receive any IP request from
> clients. When I start the isc-dhcp-server on primary server, at this
> moment I can see the DHCPREQUEST from clients to primary server.

> What can be the problem with the secondary server please ???

> Thanks a lot!!!
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
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