<div dir="ltr"><p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Hello dhcp-users</span></p><p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"><br></span></p><p class="MsoNormal" style="margin:0cm 0cm 0.0001pt"><font face="Arial, sans-serif"><span style="font-size:13.3333px">Yesterday I wrote the same mail to the list, but it never appeared in the arrchives or in my inbox. Therefor i resend the mail from another address. sorry if the messaged is now sent multiple times</span></font></p><p class="MsoNormal" style="margin:0cm 0cm 0.0001pt"><font face="Arial, sans-serif"><span style="font-size:13.3333px"><br></span></font></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">One of our dhcp 4.3 servers for DOCSIS died last week </span><span lang="EN-GB" style="font-size:10pt;font-family:"Segoe UI Emoji",sans-serif">☹</span><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> and we’re now in the process to set up two new servers with version 4.4
</span><span lang="EN-GB" style="font-size:10pt;font-family:"Segoe UI Emoji",sans-serif">😊</span><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">. </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">I’d like to introduce failover for some important
pools, but still have open questions</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">The configuration is split into a few pieces. </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">The static configuration part is rsynce’d once a day
to the secondary node. </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Both servers have a .local config, which contains
next-server, time-servers, server-name, the subnet declaration for the
management net and our omapi configuration</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">The dynamic part comes from another system and is
uploaded by ftp two both servers.</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">A script runs every 5 minutes and if we have new files
from ftp, we build the configuration and restart the server. The secondary
server does the same, but the daemon is not enabled, so the server won’t serve
any requests.</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">If we have a planned maintenance, we stop both server,
rsync the lease.db and start the secondary node</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Further the lease.db from the primary node is fetched
every 10 minutes to another system. So that when the primary server dies, we
have a ~10minute old lease db (depends on the last reload) that we can put on
the second node</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">If we wanna go for failover, what are the right steps
to start?</span></p>
<ol style="margin-top:0cm;margin-bottom:0cm" start="1" type="1">
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Configure failover on the
primary node (in the local confg)</span></li>
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Choose which we wanna do
failover and configure them</span></li>
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Restart the primary node and
put it into partner down state</span></li>
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Configure the second server
(failover and pools)</span></li>
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Start the second server</span></li>
<li class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Put the primary server into
partner-up? Mode</span></li>
</ol>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Does this sound right?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><b><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">/30 networks</span></b></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">We have about ~240 pools, ~50 pools only contain one
single ip address. Does failover makes sense here?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">We can’t use hosts definitions because we only know
the option-82. Some customers have more than one device connected but we can
only serve the single ip address to one of them. If we use failover, can it
happen, that server-1 hands out the ip address to device-1 and server two hand
out the ip to device-2?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><b><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Heavily used pools</span></b></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">The bigger part is our /24 pools. These are all in a
shared network config. I guess the failover part works pretty fine for the
individual pools here. The shared network is sometimes at 95% usage. Can this
lead to problems?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><b><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Server restarts</span></b></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Currently we restart the service every 5minutes if
something changed. When we go for failover, we should reload server one and if
it synced to his partner, we can reload the server two. How does server two
know, that the server one is up to date and everything is synced?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">The ISC Knowledge Base contains an article about
failover setup (<a href="https://kb.isc.org/article/AA-00502/0/A-Basic-Guide-to-Configuring-DHCP-Failover.html" style="color:blue">https://kb.isc.org/article/AA-00502/0/A-Basic-Guide-to-Configuring-DHCP-Failover.html</a>)
and part 7 is configuring OMAPI access? Who uses that? Is this for the
communication between primary and secondary or only for putting one server into
partner down mode?</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">We actually do use omapi to check and expire active
leases.</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">I’m sure that as soon as I hit send, more questions
come to my mind </span><span lang="EN-GB" style="font-size:10pt;font-family:"Segoe UI Emoji",sans-serif">😊</span><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> e.g good mctl and split values for
lease times of 1h</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">TIA for all your inputs and recommendations</span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif"> </span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-size:10pt;font-family:Arial,sans-serif">Philippe</span></p></div>