Routing

Hi,

I probably need to move from pefectly working, but legacy forwarding-options/helpers/bootp to modern forwarding-options/dhcp-relay on our MX104/MX204 router to support DHCP relay operation.

I have a router with multiple routing instances and multiple separate DHCP servers and I am a little bit scared about DHCP relay implementation using forwarding-options/dhcp-relay.

Here is my current working DHCP relay config:

forwarding-options {
helpers {
	bootp {
		relay-agent-option;
		server 192.168.1.5 routing-instance RI_XXX;
		server 192.168.1.6 routing-instance RI_XXX;

		interface {
			xe-0/1/2.799 {
				server 192.168.99.95 routing-instance RI_YYY;
				server 192.168.99.96 routing-instance RI_YYY;
			} 
...
etc.				
}

My interfaces and RE firewall filter looks like:

interfaces {
    lo0 {
        unit 0 {
            family inet {
                filter {
                    input fw_router_mgmt;
                }
                address 127.0.0.1/32;             
            }
        }
    }
}	
	
firewall {
	family {
	inet {
	
	filter fw_router_mgmt {
		...
		term 3 {
			from {
				source-address {
					0.0.0.0/32;
				}
				destination-address {
					255.255.255.255/32;
				}
				protocol udp;
				port 67;
			}
			then accept;
		}
		...			
	}}}
}

Everything works fine and there is no problem in IPv4 world.

Now, I need to switch  to forwarding-options/dhcp-relay to be able to add support for IPv6 in the future. I have found Minimum DHCP Relay Agent Configuration article, but this is for SRX platform, not for MX.

Summary of my requirements:

• MX Router with multiple routing instances and working bootp helper, fortunately no IRB interfaces
• No DHCP traffic inspection, snooping, no engineering - just forward DHCP frame from client to the DHCP server and back like bootp helper does.

I saw few pieces of puzzle to disable unwanted things that can make it even more complicated:

• use option called forward-only that should be used to disable almost all of the inspection features
• use forwarding-options dhcp-relay no-snoop
• use forwarding-options dhcp-relay forward-snooped-clients all-interfaces to permit traffic, because otherwise it could be dropped

Please, if you have a simillar setup, I'd be glad for sharing a working piece of your config, something like "Minimum DHCP Relay Agent" above,  but for MX platform.

Thank you for any feedback and support how to do the transition in no-horror way.