.. _example_protocols_bgp_parameters_graceful-restart:

################
Graceful-Restart
################

Scenario to verify BGP **graceful-restart** global parameter timers.

Graceful restart allows a BGP router to maintain forwarding state during
a restart, minimizing traffic disruption. This test suite verifies the
``stalepath-time`` and ``restart-time`` global parameters that control
how long stale routes are kept after a session goes down.

``stalepath-time`` is configured on the helper and controls the maximum
time stale paths are retained. ``restart-time`` is configured on the
restarting peer and advertised to the helper, telling it how long to
wait for the peer to restart before removing stale routes.

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Test iBGP - Graceful restart stalepath-time controls stale route expiration
***************************************************************************

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

Test that the global ``stalepath-time`` parameter controls how long the
helper retains stale routes after the restarting peer goes down. **DUT0**
(helper) is configured with ``stalepath-time 15`` (15 seconds). When **DUT1**
(restart mode) shuts down, **DUT0** marks routes as stale. After 15 seconds
the stale routes should be removed automatically, proving the timer works.

Scenario
========

.. include:: graceful-restart/testibgp-gracefulrestartstalepath-timecontrolsstalerouteexpiration

.. raw:: html

  <hr>

*********************************************************************
Test iBGP - Graceful restart restart-time controls helper wait period
*********************************************************************

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

Test that the global ``restart-time`` parameter controls how long the helper
waits for the restarting peer before removing stale routes. DUT0 (restart mode)
is configured with ``restart-time 10`` (10 seconds), which is advertised to
DUT1 (helper). When DUT0 goes down, DUT1 should keep stale routes for only
10 seconds before removing them, proving the advertised timer is respected.

Scenario
========

.. include:: graceful-restart/testibgp-gracefulrestartrestart-timecontrolshelperwaitperiod

.. raw:: html

  <hr>