.. _example_service_dhcp-server_failover-split-brain:

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Failover-Split-Brain
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Test suite for DHCP Failover split-brain scenarios.

Split-brain occurs when both DHCP servers lose communication
with each other but both remain operational. Each server thinks
the other is down and may enter "communications-interrupted" state.

This test suite verifies:
- Both servers detect communications-interrupted state
- Clients can still obtain IPs during split-brain
- Servers recover to normal state when communication is restored

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Test Split-Brain Detection
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Description
===========

This scenario verifies that when communication between
primary and secondary DHCP servers is blocked, both servers
detect the issue and enter "communications-interrupted" state.

The failover protocol uses port 647 for peer communication.
By blocking this port, we simulate a network partition.

Expected behavior:
- Initially both servers are in "normal" state
- After blocking port 647, both detect "communications-interrupted"
- Servers may also show "partner down" after timeout

Scenario
========

.. include:: failover-split-brain/testsplit-braindetection

.. raw:: html

  <hr>

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Test Split-Brain Client Still Gets IP
*************************************

Description
===========

This scenario verifies that during a split-brain condition,
DHCP clients can still obtain IP addresses from one of the
servers. The failover protocol is designed to allow both
servers to serve clients during communication interruption.

Expected behavior:
- Split-brain is active (servers can't communicate)
- Client requests DHCP lease
- Client successfully obtains IP from available server

Scenario
========

.. include:: failover-split-brain/testsplit-brainclientstillgetsip

.. raw:: html

  <hr>

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Test Split-Brain Recovery
*************************

Description
===========

This scenario verifies that after a split-brain condition
is resolved (communication restored), both servers recover
to normal state and synchronize their lease databases.

Expected behavior:
- Start in split-brain state
- Remove traffic blocking rules
- Both servers recover to "normal" state
- Lease databases are synchronized

Scenario
========

.. include:: failover-split-brain/testsplit-brainrecovery

.. raw:: html

  <hr>