DHCP server help please

[Ninjin25]

Hello, I have recently inherited a network and need to add a new DHCP statement, but in the logs I am getting unknown network segment. This network is kind large and has many VLANs and many different subnets. Each VLAN is setup to be associated with a MAC address and has a 255.255.255.252 subnet mask. This particular new device is going to be 172.17.20.70/30. So the VLAN that I created on the core switch is VLAN 268, 172.17.20.69 255.255.255.252 and it is a routing VLAN. This scheme matches the other working VLANs. Here is what the dhcp.conf entry looks like: subnet 172.17.20.68 netmask 255.255.255.252 { range 172.17.20.70; option domain-name-servers ns1.xxxx.com, ns2.xxxxx.com; option domain-name ;xxx.com; option routers 172.17.20.69; default-lease-time 43200; default-lease-time 86400; authoritative; } This matches all the other existing and working DHCP entries. I get a entry in the syslog that specifically states "unknown network segment". Well I know that this is pretty much telling me that this is an unknown network, even though there are dozens more entries like the one above like this working one: subnet 172.17.20.64 netmask 255.255.255.252 { range 172.17.20.66; option domain-name-servers ns1.xxxxxx.com, ns2.xxxxx.com; option domain-name xxxxxx.com; option routers 172.17.20.65; default-lease-time 43200; default-lease-time 86400; authoritative; } I really am at a loss at this time, I have done everything that I know. I'm not sure where else I can look on the DHCP server to see what is going on. The other other thing I can think of is I have bond0,eth0, and eth1 bond0 and eth0 share the same IP address. eth1 reports as being down and doesn't have an IP address. I wouldn't think that this would be an issue since I have well over 100 addresses being assigned out by this same server. Any thoughts or help will be much appreciative.

[Iowan]

Quite a wall of words...
I'm probably missing something (like VLAN's) - or just don't understand that DHCP server (which one is it?), but shouldn't the range statement have more than one address?

[Ninjin25]

Wow sorry about that, don't know what happened to the formatting of that post, but lets try again.

This network is actually a lab to test network equipment in. I made the range only have 1 address because of the 255.255.255.252 subnet mask. I can only have 2 usable addresses, the gateway and the actual IP address. I have tried larger subnet masks. What I haven't done, but going to start working on in a moment is the following:

1. Try something other than 172.17.20.x, such as 172.17.21.x/24
2. Try another device, or switch the VLAN MAC associations with a working device.

So here is the topology:


[Router]----Layer 3 switch(core)----L2 switch---item I'm wanting to add
|
Layer 2 switch----DHCP server.

Now I know it would be better to simply this. But, DHCP works for about 70 devices which was added by the previous admin. Many of these devices are using a 255.255.255.252 subnet mask.

So this is what I have

On my switch this is what I have for this particular device. Do keep in mind that I have many more VLAN just like this one that works.

VLAN 268=172.17.20.69/255.255.255.252
VLAN 268 has a mac association with ----:1d:15:f9(which is the device in question)
All correct ports are participating members, and this is a routing VLAN

My DHCP Configuration, top one is the exiting working one, the bottom one in bold is mine:


subnet 172.17.20.64 netmask 255.255.255.252 {
range 172.17.20.66;
option domain-name-servers ns1.prosupportlab.com, ns2.prosupportlab.com;
option domain-name "prosupportlab.com";
option routers 172.17.20.65;
default-lease-time 43200;
default-lease-time 86400;
authoritative;
}

subnet 172.17.20.68 netmask 255.255.255.252 {
range 172.17.20.70;
option domain-name-servers ns1.xxxxb.com, ns2.xxxx.com;
option domain-name "xxxx.com";
option routers 172.17.20.69
default-lease-time 43200;
default-lease-time 86400;
authoritative;
}

Error seen in logs:

Feb 19 16:18:27 ns1 dhcpd: DHCPDISCOVER from -----:15:f9 via 172.17.20.69: unknown network segment

So from what I can tell the device I am trying to get connected is being seen by the DHCP server via appropriate routing; the server just doesn't know how to respond. Not sure if I need to do anything else to tell the server that this network segment isn't ummm unknown.

[Iowan]

The formatting helps! :D
I understand your subnetting, now... well, sorta.
I'm grasping a bit, but I presume it's just a typo that there's no semicolon after option routers 172.17.20.69?

[Ninjin25]

That was an error in my dhcpd.conf file which I have since fixed; unfortunately no go still.

I removed the VLAN 268 and created a new one in a different subnet this time 172.17.200.0/24. Then created a new DHCP pool that I have since deleted so I can not give the config of it.

I probably messed up on the config, long day, very tired, and extremely frustrated lol. But, that didn't even get logged so idk.

I am still in contact with the previous admin, I am just going to call him tomorrow before I lose any more hair on this one.

If anyone can think of anything that I can check, please let me know.