What actions are triggered by gateway going down?

jonallport

Apologies of this has been answered elsewhere, but I can't for the life of me find it!

What are the 'actions' that occur when a gateway monitor declares a gateway as down? And are they configurable?

TLDR: WAN DHCP does not release/renew if the upstream connection drops unless the interface is cycled or actioned from the interface status UI. How to fix?

Long version:
Netgate 1100
2x WAN connections
1x FTTP PPPoE - Tier 1
1x LTE via gateway in passthrough mode - Tier 2

The LTE is piped through the house on a transit VLAN rather than connected to the firewall as I have the firewall at ground level and want the LTE gateway as high up as possible. Gateway is in passthrough so I get the public IP on my WAN interface (and no double-NAT).

Both connections have gateway monitors pinging remote IPs. Failover FTTP>LTE works great. Fail-back works, too.

Now the problem...
FTTP PPPoE goes down: PPP client continuously retries to initiate the connection until it succeeds - good
LTE carrier goes down: interface just sits there and carries on pinging the remote IP - bad

The LTE will probably reconnect with a different IP address, so I need the interface to release / renew the DHCP lease when the gateway goes down. I've run packet capture while I kill the LTE and see no evidence of any attempt to repair/re-initialise the connection. Just carries on pinging the nominated IP in forlorn hope...

Any hints on a solution to this? Other than notifications and manual intervention

Thanks in advance

jonallport

It would seem the answer to my question is "/etc/rc.gateway_alarm" is run.

Nothing in there for DHCP leases from what I see. More about restarting VPN sessions and flushing states.

jonallport

For the benefit of my future self…

I’ve got the LTE interface to renew DHCP every 15 minutes. Not ideal, but should be enough to keep me online.

Interface / DHCP client configuration / Advanced configuration / “Option modifiers” = “supersede dhcp-lease-time 1800”

This requests the max lease time of 30 minutes, so renewal triggers in 1800/2 = 900s (15min)