How configuring forwarding DHCP

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- bratbasen
  
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posted
17 years ago

Thu, Jul 13, 2006 6:12 PM

Hi I`m have 4 Vlan for switch Catalyst 3550 - connecting to router 3660 on FE

0/1 via trunk: vlan 1 - 192.168.10.0/24 vlan 2 - 192.168.11.0/24 vlan 3 - 192.168.12.0/24 vlan 4 - 192.168.13.0/24 and I`m have server DHCP on Windows 2000 Server(192.168.0.10) - he is connecting on FE 0/0 (router cisco 3660 with network address 192.168.0.1/24) How configuring switch, router in order to server DHCP will giveing ip address to: vlan 1 - 192.168.10.0/24 vlan 2 - 192.168.11.0/24 vlan 3 - 192.168.12.0/24 vlan 4 - 192.168.13.0/24

Please help me!!

Thanks , Christopher

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- BernieM
  
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posted
17 years ago

Thu, Jul 13, 2006 7:20 PM

Apply "ip helper-address 192.168.0.10" to all VLAN interfaces that have hosts needing to use the DHCP server.

BernieM

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- Matthew Melbourne
  
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posted
17 years ago

Thu, Jul 13, 2006 7:33 PM

Add "ip helper-address 192.168.0.10" under each of the subinterfaces of fa0/1 on the router. Also, globally, add the following commands:

no ip forward-protocol udp tftp no ip forward-protocol udp domain no ip forward-protocol udp time no ip forward-protocol udp netbios-ns no ip forward-protocol udp netbios-dgm no ip forward-protocol udp tacacs

Activating a helper-address automatically forwards seven types of udp traffic by default; only one of those (bootpc) is actually required.

Create scopes on the W2k server and it should work. The router will modify the DHCP request when it converts the broadcast into a unicast and forwards it to the designated helper-address, to include the "giaddr" field which the server uses to determine the scope from which the address should be taken.

Also, make sure you don't have "no service dhcp" configured, as this will prevent DHCP relaying working.

Cheers,

Matt