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Today's Topics:
1. Re: DHCP failover doesn't receive DHCP requests in secondary
server (Chris Buxton)
2. RE: DHCP failover doesn't receive DHCP requests in secondary
server (greg.ra...@bt.com)
3. Re: DHCP failover doesn't receive DHCP requests in secondary
server (Gregory Sloop)
4. Re: DHCP failover doesn't receive DHCP requests in secondary
server (Philippe Maechler)
----------------------------------------------------------------------
Message: 1
Date: Wed, 15 Aug 2018 08:59:42 -0700
From: Chris Buxton <cli...@buxtonfamily.us>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID: <e8d10cda-dde0-41c3-bf00-fd8b10c19...@buxtonfamily.us>
Content-Type: text/plain; charset=utf-8
Both are active. Roughly 50% of clients will be answered by each, under normal
circumstances.
Chris Buxton
> On Aug 15, 2018, at 8:58 AM, Roberto Carna <robertocarn...@gmail.com> wrote:
>
> Dear, thanks for your response...So I will review the DHCP agent as you said.
>
> But now I have a question:
>
> If both DHCP servers always receive DHCPREQUEST packets, does it mean
> that in normal condition (primary and secondary server are running UP)
> both DHCP servers responds these requests ??? Or only the primary
> server responds the requests in despite of the secondary server is UP
> too ???
>
> Thanks a lot again, regards !!!
>
> 2018-08-15 12:38 GMT-03:00 perl-list <perl-l...@network1.net>:
>> 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" <robertocarn...@gmail.com>
>>> To: "Users of ISC DHCP" <dhcp-users@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@lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users@lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
------------------------------
Message: 2
Date: Wed, 15 Aug 2018 16:07:50 +0000
From: <greg.ra...@bt.com>
To: <dhcp-users@lists.isc.org>
Subject: RE: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID:
<f9144e855e7c47a6abe23c4889d2e...@tpw09926dag06g.domain1.systemhost.net>
Content-Type: text/plain; charset="utf-8"
Please note that it depends on the type of DHCPREQUEST packets. DHCPREQUESTs
for clients in the RENEWING state will be unicast to the server that issued the
lease, i.e. the primary DHCP server. DHCPREQUESTs for clients in the REBINDING
state will be broadcast, and therefore should be received by both primary and
failover DHCP servers. This is true for clients on the same LAN or separated
by a DHCP relay. In the case of a DHCP relay, it will see the broadcast packet
and (should be configured to) forward to both primary and failover. Unicast
packets, of course, will not be relayed, but simply routed to the destination
IP. DHCPDISCOVER packets are always broadcast.
Regards,
Greg Rabil
-----Original Message-----
From: dhcp-users [mailto:dhcp-users-boun...@lists.isc.org] On Behalf Of Chris
Buxton
Sent: Wednesday, August 15, 2018 12:00 PM
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary server
Both are active. Roughly 50% of clients will be answered by each, under normal
circumstances.
Chris Buxton
> On Aug 15, 2018, at 8:58 AM, Roberto Carna <robertocarn...@gmail.com> wrote:
>
> Dear, thanks for your response...So I will review the DHCP agent as you said.
>
> But now I have a question:
>
> If both DHCP servers always receive DHCPREQUEST packets, does it mean
> that in normal condition (primary and secondary server are running UP)
> both DHCP servers responds these requests ??? Or only the primary
> server responds the requests in despite of the secondary server is UP
> too ???
>
> Thanks a lot again, regards !!!
>
> 2018-08-15 12:38 GMT-03:00 perl-list <perl-l...@network1.net>:
>> 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" <robertocarn...@gmail.com>
>>> To: "Users of ISC DHCP" <dhcp-users@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@lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users@lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
dhcp-users mailing list
dhcp-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users
------------------------------
Message: 3
Date: Wed, 15 Aug 2018 09:15:45 -0700
From: Gregory Sloop <gr...@sloop.net>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID: <142198639.20180815091...@sloop.net>
Content-Type: text/plain; charset="utf-8"
Top posting:
I think the term "fail over" causes some confusion.
DHCPd in "fail-over" isn't what I'd typically think of, when I think "fail
over."
When I think fail-over, I think of a server that essentially does no active
"work" while the primary is up and functioning - other than *getting ready* to
handle the load of the primary when it goes down.
Yet DHCPd fail-over is really *load-balancing* [at least in "normal" setups]
with a bunch of communication between the two to handle the
failure/unavailability of *either* server.
Thus, in regular practice, both servers are seeing requests and answering them,
and [again in "normal" setups] will have approximately half of the leases
distributed to each server.
HTH
-Greg
RC> Dear, thanks for your response...So I will review the DHCP agent as you
said.
RC> But now I have a question:
RC> If both DHCP servers always receive DHCPREQUEST packets, does it mean
RC> that in normal condition (primary and secondary server are running UP)
RC> both DHCP servers responds these requests ??? Or only the primary
RC> server responds the requests in despite of the secondary server is UP
RC> too ???
RC> Thanks a lot again, regards !!!
RC> 2018-08-15 12:38 GMT-03:00 perl-list <perl-l...@network1.net>:
>> 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" <robertocarn...@gmail.com>
>>> To: "Users of ISC DHCP" <dhcp-users@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!!!
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Message: 4
Date: Wed, 15 Aug 2018 18:19:05 +0200
From: Philippe Maechler <plcmaech...@gmail.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID:
<CAPhukgYJnG2-ZVt9rOU1zJ_UKk1NVE-5yVc5-mjn6s_dCW=8...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
iirc with the latest patch, only the primary server replies to clients when
the split value is set to 255
Gregory Sloop <gr...@sloop.net> schrieb am Mi., 15. Aug. 2018, 18:16:
> Top posting:
>
> I think the term "fail over" causes some confusion.
> DHCPd in "fail-over" isn't what I'd typically think of, when I think "fail
> over."
>
> When I think fail-over, I think of a server that essentially does no
> active "work" while the primary is up and functioning - other than *getting
> ready* to handle the load of the primary when it goes down.
>
> Yet DHCPd fail-over is really *load-balancing* [at least in "normal"
> setups] with a bunch of communication between the two to handle the
> failure/unavailability of *either* server.
>
> Thus, in regular practice, both servers are seeing requests and answering
> them, and [again in "normal" setups] will have approximately half of the
> leases distributed to each server.
>
> HTH
> -Greg
>
>
>
>
>
>
>
>
>
>
>
>
>
> *RC> Dear, thanks for your response...So I will review the DHCP agent as
> you said. RC> But now I have a question: RC> If both DHCP servers always
> receive DHCPREQUEST packets, does it mean RC> that in normal condition
> (primary and secondary server are running UP) RC> both DHCP servers
> responds these requests ??? Or only the primary RC> server responds the
> requests in despite of the secondary server is UP RC> too ??? RC> Thanks a
> lot again, regards !!! RC> 2018-08-15 12:38 GMT-03:00 perl-list <*
> perl-l...@network1.net*>:*
>
>
>
>
>
>
>
>
> * >> 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" <*
> robertocarn...@gmail.com*>*
>
> * >>> To: "Users of ISC DHCP" <*
> dhcp-users@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@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
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