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Configuring DHCP-relay with VLAN's

I'm doing a small lab. I need to make DHCP pools for VLAN's on Router1 and configure DHCP-relay agent on Router1 so PC's from VLAN 300 and 400 could recieve addresses from pools in Router0.
I made the pools, but I'm really confused about configuring Router1. I rellay hope someone would help me out!
UgnBP_croper_ru.png

The file I attached is renamed .pkt. I'm using Packet Tracer version 6.3. Thanks for you help!

7 REPLIES
Silver

Re: Configuring DHCP-relay with VLAN's

Assuming you're using sub-interfaces on Router1, you'll just need to configure the "ip helper-address" command pointing to R0.

Community Member

Re: Configuring DHCP-relay with VLAN's

I know that, but I'm confused about which IP adresses I should give to all Router1 subinterfaces (Fa0/0 and Fa0/1)
Silver

Re: Configuring DHCP-relay with VLAN's

It can be whatever you want, but typically it's their default gateway.

Community Member

Re: Configuring DHCP-relay with VLAN's

some address from VLAN 300 - Fa0/1.300
some address from VLAN 400 - Fa0/1.400
what about Fa0/0.300 and Fa0/0.400?
Silver

Re: Configuring DHCP-relay with VLAN's

FA0/0.100, FA0/0.200, FA0/1.300 & FA0/0.400 can be whatever address you want in their respective subnet, just make sure to include the helper address on each interface that utilized R0 for DHCP.

VIP Purple

Re: Configuring DHCP-relay with VLAN's

Hello

 

Note:- if all you clients are only internal from rtr1 then you don't require any dhcp relay on rtr if that rtr is supplying dhcp.

The problem  you've got isnt the Dhcp allocation its the topology setup, What is Rtr 0 suppose to be doing?

You have to physical interfaces on rtr1 which can be both configured as sub-interface for the vlans ( "router on a stick" scenario)  - however whats the addressing for rtr 0 as this will require one.

 

Can you elaborate your end goal for this please.

res
Paul

Please don't forget to rate any posts that have been helpful.

Thanks.
VIP Purple

Re: Configuring DHCP-relay with VLAN's

Hello,

 

please find attached the working config. I am not sure what the requirement is, but some major changes were needed. I deleted the subinterfaces for Vlan 300 and Vlan 400 on Router0 and on FastEthernet0/0 of Router1, since that couldn't work: you were trying to configure the same subnet on three interfaces.

I added a subinterface for Vlan 100 and Vlan 200 on Router 1, and added IP heloer addresses on the Vlan 300 and Vlan 400 subinterfaces of Router1.

I also added static routes on Router0 pointing to Router1. And last but not least, all switchports were configured with 'spanning-tree portfast'.

When you open the file, give it a minute or two to converge. Then try to release/renew the IP addresses.

 

 

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