Tue Jun 8 18:59:23 UTC 2010

you dont want to define this as a shared network.
On the switch you have also confused the two networks using the helper-address statement.
if you want these vlans to be separate networks they must remain separate. (layer 2)
at some point the vlans will connect to a router. (layer 3) on that router will be a gateway interface. that interface will usually have a bootphelper statement that forwards broadcast dhcp traffic to the address of your dhcp server (and back)

Randall Grimshaw rgrimsha at syr.edu<mailto:rgrimsha at syr.edu>

________________________________
From: dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org [dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org] On Behalf Of Difan Zhao [difan.zhao at guest-tek.com]
Sent: Tuesday, June 08, 2010 1:56 PM
To: dhcp-users at lists.isc.org
Subject:

Hi experts,

I am trying to provide dynamic IP addresses for devices that are resided on VLAN 101. The server is currently providing 172.17.x.x/16 range for its own VLAN 417. My server is RHEL4 running DHCPD version 3.0.1. The core switch (Cisco 3750) is configured with “ip helper-address 172.17.1.1” on VLAN 101 interface. Here is my dhcpd.conf file:

authoritative;
ddns-update-style ad-hoc;
omapi-port 7911;

shared-network eth1
{
option domain-name "globalsuite.net";
option domain-name-servers 4.2.2.1;
default-lease-time 88200;
max-lease-time 88200;

   subnet 172.17.0.0 netmask 255.255.0.0
   {
       range 172.17.1.10 172.17.199.254;
       option broadcast-address 172.17.255.255;
       option routers 172.17.1.1;
       option subnet-mask 255.255.0.0;
   }

   subnet 192.168.1.0 netmask 255.255.255.0
   {
       range 192.168.1.10 192.168.1.250;
       option broadcast-address 192.168.1.255;
       option routers 192.168.1.254;
       option subnet-mask 255.255.255.0;
   }
}

Here is my eth1:
[root at NE_OVI ~]# ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:15:C5:F4:CB:22
inet addr:172.17.1.1 Bcast:172.17.255.255 Mask:255.255.0.0

Here is my routing table on the server. The eth0 is WAN interface, connected with ISP. The eth1 is LAN interface on VLAN 101. The server is also doing NAT/PAT for the LAN users.

[root at NE_OVI ~]# route -n
Kernel IP routing table
Destination               Gateway                  Genmask                 Flags Metric Ref Use           Iface
210.83.99.128          0.0.0.0                    255.255.255.128       U 0 0 0                              eth0
192.168.1.0             172.17.254.1           255.255.255.0          UG 0 0 0                            eth1
0.0.0.0                    210.83.99.129          0.0.0.0                    UG 0 0 0                            eth0

Configs on the switch:
!
interface Vlan417
ip address 172.17.254.1 255.255.0.0
no ip route-cache
end
!
interface Vlan101
ip address 192.168.1.254 255.255.255.0
ip helper-address 172.17.1.1
end
!

However my laptop on the VLAN 101 keeps getting IP of 172.17.x.x/16 range... Here is the log.

Jun  8 11:53:47 NE_OVI dhcpd: DHCPDISCOVER from 00:11:43:fe:80:19 (ne-l-d400tester) via 192.168.1.254
Jun  8 11:53:47 NE_OVI dhcpd: DHCPOFFER on 172.17.199.253 to 00:11:43:fe:80:19 (ne-l-d400tester) via 192.168.1.254
Jun  8 11:53:47 NE_OVI dhcpd: if ne-l-d400tester.globalsuite.net IN A rrset doesn't exist add ne-l-d400tester.globalsuite.net 44100 IN A 172.17.199.253: timed out.
Jun  8 11:53:47 NE_OVI dhcpd: DHCPREQUEST for 172.17.199.253 (172.17.1.1) from 00:11:43:fe:80:19 (ne-l-d400tester) via 192.168.1.254
Jun  8 11:53:47 NE_OVI dhcpd: DHCPACK on 172.17.199.253 to 00:11:43:fe:80:19 (ne-l-d400tester) via 192.168.1.254

Where do I do wrong? How do I fix it?

Thanks!

Difan Zhao, M.Eng
Network Engineer
Guest-Tek Interactive Entertainment Inc.
www.guest-tek.com<http://www.guest-tek.com>

Email: difan.zhao at guest-tek.com<mailto:difan.zhao at guest-tek.com>
Office: +1 (403) 509 1010 ext 3048
Cell: +1 (403) 689 7514

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