Cisco - Linux Dhcp-relay setting

This is the configuration of router as dhcp-relay and linux as dhcp server

Diagram :
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1. Interface configuration :

!
interface GigabitEthernet0/0.11
description ### Test Internet ###
encapsulation dot1Q 11
ip dhcp relay information trusted
ip dhcp relay information option vpn-id none
ip vrf forwarding vpn_internet
ip address 192.168.78.201 255.255.255.252
ip helper-address 192.168.78.198
end

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Config note :

ip dhcp relay information trusted

Usage Guidelines

By default, if the gateway address is set to all zeros in the DHCP packet and the relay information option is already present in the packet, the Cisco IOS DHCP relay agent will discard the packet. If the ip dhcp relay information trusted command is configured on an interface, the Cisco IOS DHCP relay agent will not discard the packet even if the gateway address is set to all zeros. Instead, the received DHCPDISCOVER or DHCPREQUEST messages will be forwarded to the addresses configured by the ip helper-address command as in normal DHCP relay operation.

ip dhcp relay information option vpn-id

To enable the system to insert VPN suboptions into the DHCP relay agent information option in forwarded BOOTREQUEST messages to a DHCP server and set the gateway address to the outgoing interface toward the DHCP server, use the ip dhcp relay information option vpn-id command in interface configuration mode. To remove the configuration, use the no form of this command.

refference : http://www.cisco.com/en/US/docs/ios/ipaddr/command/reference/iad_dhc2.html#wp1012293

2. Edit dhcp configuration :

root@desktop:# vi /etc/dhcp3/dhcpd.conf

ddns-update-style none;

default-lease-time 600;
max-lease-time 7200;

#authoritative;

log-facility local7;

option subnet-mask 255.255.255.252;
option broadcast-address 192.168.78.203;
option routers 192.168.78.201;

subnet 192.168.78.200 netmask 255.255.255.252 {
range 192.168.78.202;
}


3. Checking log :

Jul 15 18:17:22 -desktop dhcpd: DHCPDISCOVER from 00:0a:e4:36:03:a0 via 192.168.78.201
Jul 15 18:17:23 -desktop dhcpd: DHCPOFFER on 192.168.78.202 to 00:0a:e4:36:03:a0 (LENOVO-2EB43090) via 192.168.78.201
Jul 15 18:17:23 -desktop dhcpd: DHCPREQUEST for 192.168.78.202 (192.168.78.198) from 00:0a:e4:36:03:a0 (LENOVO-2EB43090) via 192.168.78.201
Jul 15 18:17:23 -desktop dhcpd: DHCPACK on 192.168.78.202 to 00:0a:e4:36:03:a0 (LENOVO-2EB43090) via 192.168.78.201
Jul 15 18:17:25 -desktop dhcpd: DHCPREQUEST for 192.168.78.202 from 00:0a:e4:36:03:a0 (LENOVO-2EB43090) via eth1
Jul 15 18:17:25 -desktop dhcpd: DHCPACK on 192.168.78.202 to 00:0a:e4:36:03:a0 (LENOVO-2EB43090) via eth1

Have a good try.. :)