.. _example_protocols_bgp_parameters_confederation:

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Confederation
#############

Scenario to verify BGP **confederation** parameter configuration.

BGP confederations allow dividing an autonomous system into multiple
sub-autonomous systems while presenting a single AS to external peers.
The ``confederation identifier`` defines the public AS number visible to
the outside, while each router runs BGP with its sub-AS number. The
``confederation peers`` command lists the other sub-AS numbers that belong
to the same confederation.

The scenario covers three cases by checking the neighbor link type
reported by FRR in ``show ip bgp neighbors``:

- **confed-internal link** — both DUTs in the same sub-AS (65001) with
  confederation parameters configured.
- **confed-external link** — DUTs in different sub-ASes (65001 and
  65002) that declare each other as ``confederation peers`` under the
  same identifier 100.
- **internal link** — same topology without confederation, used as
  baseline to confirm that the ``confed-*`` results above are caused
  by the confederation configuration.

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Test iBGP - Confederation parameters change peer link type to confed-internal
*****************************************************************************

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

Test that ``confederation identifier`` and ``confederation peers`` are
correctly applied. **DUT0** and **DUT1** are in the same sub-AS (65001)
with confederation identifier 100 and peer 65002. The test verifies
that FRR reports the neighbor as ``confed-internal link`` (instead of
``internal link``), proving the confederation is active. It also verifies
that routes are exchanged correctly within the confederation sub-AS.

Scenario
========

.. include:: confederation/testibgp-confederationparameterschangepeerlinktypetoconfed-internal

.. raw:: html

  <hr>

***************************************************************************************
Test BGP - Neighbor remote-as matching confederation peers reports confed-external link
***************************************************************************************

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

Test that a neighbor whose ``remote-as`` matches a value listed in
``parameters confederation peers`` is accepted at commit time and
recognized by FRR as a peer in another sub-AS of the same
confederation. **DUT0** is configured in sub-AS 65001 and **DUT1**
in sub-AS 65002, with both declaring each other under
confederation identifier 100. The test verifies that FRR reports
the neighbor as ``confed-external link`` and that routes are
exchanged between the sub-ASes.

Scenario
========

.. include:: confederation/testbgp-neighborremote-asmatchingconfederationpeersreportsconfed-externallink

.. raw:: html

  <hr>

************************************************************
Test iBGP - Without confederation peer link type is internal
************************************************************

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

Test that without confederation parameters, the same iBGP topology
reports the neighbor as standard ``internal link``. This serves as
a baseline to confirm that the ``confed-internal link`` and
``confed-external link`` outputs in the previous tests are caused
by the confederation configuration.

Scenario
========

.. include:: confederation/testibgp-withoutconfederationpeerlinktypeisinternal

.. raw:: html

  <hr>