ISC-dhcp subnet limit?

[dave c]

Curious why your network seems to have 6,000 subnets all living in a single vlan...

But, in order to diagnose the partner issue, we'd need to see the partner config segments as well.

To answer whether it matters if requests arrive on eth1 and answers go out on eth0, the real 
question is what are the differences between them. Does one go out to a firewall while the 
second is a direct connection? I don't see a statement in your config telling dhcpd which IP 
address/port to listen and respond on. You can force it to use eth1 if you feel it should be 
doing so.

I'm also wondering why your lease time is so short. That would seem to generate a lot of traffic 
to the dhcp server that otherwise wouldn't be needed. How many users are there in these 6,000 
subnets?

Dave

On 1/27/16 19:12, Rob Morin wrote:
> Hello all, my first post here, so please be gentle J
>
> 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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-- 
Dave Calafrancesco