ISC-dhcp subnet limit?

[Rob Morin]

Hello all, my first post here, so please be gentle :)

I have inherited 2 dhcp servers, one primary(dhcp-1) & one secondary(dhcp-2) running isc-dhcpd-4.2.4 on Ubuntu 14.0(Trusty)

We are having a few issues, and I cannot seem to figure out whats going on. I have a few questions, maybe someone can help me with.


Is there a max limit to how many subnets can be used in the pools? As currently we are using just over 6000 subnets

Currently our secondary dhcp-server is always in recovery mode, not sure why?

Does it matter if a DISCOVER comes in on eth1 but OFFER goes out on eth0?

My primary server /etc/dhcpd.conf file

authoritative;
log-facility local7;
option domain-name "dyn";
option domain-name-servers 172.30.64.210, 172.30.64.220;
default-lease-time 1200;
max-lease-time 3600; # 1h
include "/etc/dhcp/dhcpd_pools.conf";
# Include the primary configuration
include "/etc/dhcp/dhcpd_primary.conf";


/etc/dhcp/dhcpd_primary has the following
                              ## PRIMARY
failover peer "tdl-dhcp-failover" {
  primary; # declare this to be the primary server
               address 172.30.128.9;
               port 647;
  peer address 172.30.128.10;
  peer port 647;
  max-response-delay 30;
  max-unacked-updates 10;
  load balance max seconds 3;
  mclt 1800;
  split 128;
}

Exert from dhcpd_pools file, starts like this....

subnet 10.32.0.0 netmask 255.255.255.0 {
  option routers 10.32.0.1;
  pool {
        failover peer "dhcp-failover";
        range 10.32.0.5 10.32.0.254;
  }
}

And finishes like this, with all the subnets in between...

subnet 10.57.255.0 netmask 255.255.255.0 {
  option routers 10.57.255.1;
  pool {
        failover peer "dhcp-failover";
        range 10.57.255.5 10.57.255.254;
  }
}


Example Exert from logs on both serves of a client that could not get an IP

from dhcp-1
Jan 27 18:30:31 dhcp-1 dhcpd: DHCPDISCOVER from fc:e9:98:bc:a8:7b (iPhone) via 10.50.170.1
Jan 27 18:30:31 dhcp-1 dhcpd: DHCPOFFER on 10.50.170.93 to fc:e9:98:bc:a8:7b (iPhone) via 10.50.170.1

from dhcp-2
Jan 27 18:53:55 dhcp-2 dhcpd: DHCPDISCOVER from fc:e9:98:bc:a8:7b via 10.50.170.1: peer holds all free leases
Jan 27 18:54:04 dhcp-2 dhcpd: DHCPDISCOVER from fc:e9:98:bc:a8:7b via 10.50.170.1: peer holds all free leases

Never see the ACK.

Any suggestion would be greatly appreciated.. :

Thanks...

Rob
Montreal Canada

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