[Glenn Satchell]

A shared-network is where you have different IP subnets on the same 
VLAN. Perhaps this dhcp setup came before the separation onto two 
different VLANs?

regards,
-glenn

On 06/09/10 05:13, Difan Zhao wrote:
> Thanks for reply!
>
> I just moved the “subnet 192.168.1.0/24” section out of the “shared
> network eth1” and everything works!
>
> Yes you are right. I want to separate devices at layer two. The devices
> on the VLAN 101 are actually phones. That’s why I set the
> default-gateway/router option of this subnet to the IP address of the
> core switch (which is layer 3 switch and capable of doing routing).
>
> I guess my problem was on this “shared-network”. I will study more on
> this. The server was originally set by somebody else. I will try
> understand why he was setting it this way, and if there is no good
> reason, I will remove them all…
>
> Thanks for help again!
>
> 	
>
> *Difan Zhao**, M.Eng***
>
> *Network Eng**ineer*
>
> *difan.zhao at guest-tek.com <mailto:difan.zhao at guest-tek.com>*
>
> *www.guest-tek.com <http://www.guest-tek.com/>*
>
> *Office: 403-509-1010 ext 3048*
>
> *Cell: 403-689-7514***
>
> ------------------------------------------------------------------------
>
> *From:* dhcp-users-bounces+difan.zhao=guest-tek.com at lists.isc.org
> [mailto:dhcp-users-bounces+difan.zhao=guest-tek.com at lists.isc.org] *On
> Behalf Of *Randall C Grimshaw
> *Sent:* June-08-10 12:59 PM
> *To:* Users of ISC DHCP
> *Subject:* RE:
>
> 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
>
> http://www.guest-tek.com/images/Guest-Tek%20-%20Formal_files/Logo.jpg