.. _example_protocols_bgp_parameters_no-fast-external-failover:

#########################
No-Fast-External-Failover
#########################

Scenario to verify BGP **no-fast-external-failover** parameter configuration.

By default, BGP immediately resets a session when the directly connected link to an
eBGP peer fails. This behavior is called fast external failover. The
``no-fast-external-failover`` parameter disables this behavior, causing BGP to wait
for the holdtimer to expire before declaring the session down. This can be useful in
environments where brief link flaps should not trigger BGP reconvergence.

In this test, **DUT0** (AS 100) establishes an eBGP session with **DUT1** (AS 200).
First, without ``no-fast-external-failover``, disabling DUT0's interface causes the
session to drop immediately. Then, with ``no-fast-external-failover`` enabled, the
session remains established briefly after the interface is disabled, until the
holdtimer expires.

************************************************
Test BGP Fast External Failover Default Behavior
************************************************

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

This test verifies the default fast external failover behavior. When **DUT0**'s
interface is disabled, the eBGP session should drop immediately without waiting
for the holdtimer to expire.

Scenario
========

.. include:: no-fast-external-failover/testbgpfastexternalfailoverdefaultbehavior

.. raw:: html

  <hr>

**********************************
Test BGP No Fast External Failover
**********************************

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

This test verifies that ``no-fast-external-failover`` prevents immediate session
reset when the local link fails. When **DUT0**'s interface is disabled, the eBGP
session should remain established briefly until the holdtimer expires.

Scenario
========

.. include:: no-fast-external-failover/testbgpnofastexternalfailover

.. raw:: html

  <hr>