Answers the question a single router could not, and that would otherwise only
have been discovered at cutover: with kea high-availability active-passive, does
exactly ONE box answer a DHCP request?
Yes. Probing sim VLAN 10 with broadcast-dhcp-discover returns offers from a
single distinct Server Identifier -- 172.31.10.252, the primary. The secondary
runs kea but stays silent. Without this the delta would have put 6 subnets and
84 static-mappings on both boxes with nothing to arbitrate them, and two kea
instances would have raced on every broadcast domain.
Worth noting the raw response count is misleading: nmap reports "Response 1 of
2" because it sends several discovers, and both replies carry the same server
identifier. Counting responses says "2 servers"; counting distinct server
identifiers says "1". The second number is the true one.
labsim now runs a real pair, mirroring production:
router1 172.31.<v>.252 priority 200 DHCP HA primary
router2 172.31.<v>.253 priority 100 DHCP HA secondary
VIP 172.31.<v>.1 floating, held by the master
That required converting router1, which held .1 directly, to .252 plus a
floating VIP -- otherwise it is two routers, not a pair. All six VRRP groups
show MASTER on router1 and BACKUP on router2.
New tooling:
- sim-ha-config.py generates each role's config, reusing unifi-to-vyos.py
--mode sim for the DHCP half so what is proven here and what production
gets share a code path. VLAN 10 correctly carries /23.
- console-apply.py applies config over the serial console, which is necessary
because a freshly installed VyOS holds the same addresses as its peer and
cannot safely be reached over the network at all until reconfigured.
Known sim-only quirk, deliberately not chased: router1 cannot ARP router2 on
the untagged VLAN 1 while every tagged VLAN works, and VRRP forms correctly on
all six groups regardless. Both OVS bonds carry identical vlan_mode/tag/trunks
and the bond MACs differ, so this is OVS bond behaviour on the native VLAN with
two bonds on one bridge -- not a VyOS config problem, and not present in
production, which uses a real switch.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
