Hi Austin,
You are correct, DHCP relay is available on our recent software releases. If I understand your config correctly you have a subnet 192.168.11.0/24 on an interface on vlan 7 and would like to relay this to a DHCP server. If you are using a router managed by a conductor the following configuration steps should work.
Start by configuring a special type of service for the DHCP relay setting the "application-type" to "dhcp-relay":
config authority <authority> service <relay service name>
enabled true
application-type dhcp-relay
access-policy <tenant>
source <tenant>
permission allow
top
The "<relay service name>" can be a name of your choosing, otherwise substitute <authority> and <tenant> with your authority name and the name of the tenant associated with your relay network-interface (in your case this would be on VLAN7).
The access-policy is used to indicate which tenants are eligible for the relay service. In terms of tenancy, DHCP is a little unusual because the initial client transactions are broadcast and the client has no IP address the tenant must be associated directly at the network-interface level. If you don't have the tenant already set on the interface you can set it like so:
config authority <authority> router <router> node <node> device-interface <device interface name> network-interface <network interface name> tenant <tenant>
Now the only thing remaining to do is create a service route with a nat-target to indicate the path to the DHCP server. This should be on the router that is the exit point to the DHCP server, ie: if you are using SVR to get from a branch to a data center router then the data center router would be the place to add the service-route. Configuration would look something like this:
config authority <authority> router <router> service-route <service route name>
service-name <relay service name>
nat-target <dhcp server address>
In the above case <service route name> is an arbitrary name you specify and <relay service name> is the service name you defined earlier. The nat-target points to the IP address of the DHCP server. If you have a redundant DHCP server on another IP address you can add a second service-route with a nat-target to that server.
The above config steps should work with a router managed by a conductor which will generate all the intermediate configuration for SVR routing to work. If you have an unmanaged router it is still possible to do this manually but it is a little more complex, let me know if you don't have a conductor and I can write up some more steps for this case.
The only other thing to note is that the DHCP relay packets being relayed will use the network-interface/address/ip-address of your interface as the gateway address (giaddr). The dhcp server will use this address in order to figure out which address-pool to assign addresses from. Not sure which server you are using but in the linux dhcpd application you might use a subnet designation like this in your dhcpd.conf:
subnet 192.168.11.0 netmask 255.255.255.0 {
// ... your dhcp config here
}Let me know if you have any questions or run into any issues getting this working.
There's also another post earlier from Gene that discusses a similar setup that might be helpful too:
https://community.128technology.com/communities/community-home/digestviewer/viewthread?GroupId=43&MID=125&CommunityKey=1cca2e49-ba26-471a-9522-f5ccd96c86fe&tab=digestviewer&ReturnUrl=%2fcommunities%2fcommunity-home%2fdigestviewer%3fcommunitykey%3d1cca2e49-ba26-471a-9522-f5ccd96c86fe%26tab%3ddigestviewer#DHCP #configurationEvan
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Evan Carson
Software Engineer
MA
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Original Message:
Sent: 01-25-2019 10:34
From: Austin Stoffel
Subject: Looking for a guide or examples for setting up DHCP Relay in 128T routers
Good morning,
I've been setting up a Guest LAN to use for Guest WiFi. I have it setup at our HQ and it's working well. So far I've added a Network Interface(Guest-LAN) to the device interface connected to the LAN and assigned it to VLAN 7. I have VMs running DNS and DHCP servers also assigned to VLAN 7. These are all on a separate subnet(192.168.11.0/24) from our Corporate LAN. Finally I have a wireless network assigned to our access points with a new SSID that puts wireless clients on VLAN 7. All of this is configured and working at our HQ location, now I would like to start testing it out at our satellite locations. I'll be able to do the same VLAN 7 configuration for the Network interfaces and wireless network at those locations, but I would like to use DHCP Relay so that I can assign IPs to guests on other guest network subnets, from the DHCP server at the HQ location, rather than configuring a DHCP server for each Guest LAN subnet.
I've seen some release notes mentioning 128T adding DHCP Relay functionality, but I have not seen any guides or configurations using it. I'd appreciate it if anyone would be able to share what their DHCP Relay configs look like.
Thanks,
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Austin Stoffel
Systems Administrator
BARD Materials
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