Customizing ONU DHCP

src/daemons/onu_dhcp.py is what makes ONUs "exist" to your BNG: for each discovered subscriber it creates a macvlan interface with the ONU's MAC and runs the real DHCP exchange (DORA for v4, SARR for v6) out of the OLT's uplink. From the BNG's point of view it looks exactly like an IPoE subscriber.

How it discovers subscribers

The daemon polls the LT plane's running config (every 20 s by default) looking for vlan-sub-interfaces — the l2-user created by Altiplano's VLAN service. Creating the ONT alone does not trigger DHCP: the L2 service on top of the UNI is required, with a frame-processing-profile that resolves to an outer VLAN. With that, the daemon resolves the wiring against the IHUB's v-VPLS and starts the client.

Testing without touching anything

Dry-run mode shows what would be discovered and which interface it would use, without creating any interface or sending packets:

PYTHONPATH=src/daemons python3 src/daemons/onu_dhcp.py --dry-run --once

It's the first diagnostic tool when "no DHCP is going out": in one shot it tells you whether the VSI exists, which VLAN it resolved, and which uplink it would use. Keep in mind that outside dry-run the daemon creates and deletes network interfaces: run it inside the container or a lab network namespace.

Environment knobs

Variable	Effect
ONU_DHCP_POLL	Reconciliation interval in seconds (default 20).
ONU_DHCP_UPLINK	Egress interface when the wire can't be derived from the IHUB (default eth1).

Set them on the OLT node of your containerlab or compose YAML, next to OLT_LT_SLOTS.

Working loop

# edit src/daemons/onu_dhcp.py
./build.sh check && ./build.sh
# redeploy and watch the daemon logs
docker logs -f <olt> 2>&1 | grep onu-dhcp

A healthy log sequence is: uplink map, then mac=... wire=... per subscriber, macvlan suXXXXXXXX over ..., and finally DHCPv4 ACK <ip> (server ..., lease ...). If you see the wire= line but never the ACK, the DISCOVER is going out and the problem is on the BNG side.