Orbi WiFi 7 RBE973
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DHCP Relay over VPN

Retired_Member
Not applicable

DHCP Relay over VPN

Hi Guys,
I have a problem with setting up DHCP relay mode over my VPN.
The VPN works ok and I can access the remote router, printers, etc via their internal IP address (192.168.0.xxx) no problem. My setup is as follows.

An SRX5308 based in the UK with DHCP enabled using ip/subnet address ranges 192.168.0.50 - 192.168.0.100/255.255.255.0 . The router has an ip of 192.168.0.1 and has a reserved/static settings from 192.168.0.2 to 192.168.0.40.

An SRXN3205 based in France with an initial setup of DHCP enabled using ip/subnet address ranges 192.168.10.2 - 192.168.10.20/255.255.255.0 . The router has an IP of 192.168.10.1.

The VPN is setup via 2 FQDN addresses using th VPN wizzard both ends to define the policies and works ok with no errors or drop outs.

The problem in on the french end. When I enable the DHCP Relay mode in the SRXN3205 it starts ok but does not relay the IP addresses from the UK.

Any Ideas?
Message 1 of 6

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MGSteve
Aspirant

Re: DHCP Relay over VPN

Just be aware that its not really a good idea to run DHCP over a VPN as if for whatever reason the VPN goes down, the computers at the remote site won't be able to get an IP address & the whole network there could go into meltdown... Personally I use DHCP on the site with the server and remote sites I use static. I could probably use a local DHCP server at each site, but for the number of PCs involved, using statics was easier.

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Message 6 of 6

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adit
Mentor

Re: DHCP Relay over VPN

Why are you trying to relay the DHCP?
Message 2 of 6
Daedalus01
Aspirant

Re: DHCP Relay over VPN

like adit said. Are you doing it so that devices on either end can see each other?
Message 3 of 6
Retired_Member
Not applicable

Re: DHCP Relay over VPN

Hi Guys,
Thanks for the replies.

I need to extend our domain over both routers to allow new client computers to be connected to the domain from both ends . We run SBS2011 as the main domain controller in th UK and wish to install a secondary server in France as the ADSL service there while being stable is not fast.
Both servers run active directory, with the UK being the primary.
DFS is also required on 2 large data drives as well.
DHCP relay will simplify the setup.

Regards,
D55
Message 4 of 6
adit
Mentor

Re: DHCP Relay over VPN

Makes no difference. Just program the remote site router DHCP to use the SBS as the DNS server. Everything will work fine.
Message 5 of 6
MGSteve
Aspirant

Re: DHCP Relay over VPN

Just be aware that its not really a good idea to run DHCP over a VPN as if for whatever reason the VPN goes down, the computers at the remote site won't be able to get an IP address & the whole network there could go into meltdown... Personally I use DHCP on the site with the server and remote sites I use static. I could probably use a local DHCP server at each site, but for the number of PCs involved, using statics was easier.
Message 6 of 6
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