:lastproofread:2021-07-12

.. include:: /_include/need_improvement.txt

######
Policy
######

Routing Policies could be used to tell the router (self or neighbors) what
routes and their attributes needs to be put into the routing table.

There could be a wide range of routing policies. Some examples are below:

* Set some metric to routes learned from a particular neighbor
* Set some attributes (like AS PATH or Community value) to advertised routes
  to neighbors
* Prefer a specific routing protocol routes over another routing protocol
  running on the same router

Example
=======

**Policy definition:**

.. code-block:: none

  # Create policy
  set policy route-map setmet rule 2 action 'permit'
  set policy route-map setmet rule 2 set as-path-prepend '2 2 2'

  # Apply policy to BGP
  set protocols bgp local-as 1
  set protocols bgp neighbor 203.0.113.2 address-family ipv4-unicast route-map import 'setmet'
  set protocols bgp neighbor 203.0.113.2 address-family ipv4-unicast soft-reconfiguration 'inbound'

Using 'soft-reconfiguration' we get the policy update without bouncing the
neighbor.

**Routes learned before routing policy applied:**

.. code-block:: none

  vyos@vos1:~$ show ip bgp
  BGP table version is 0, local router ID is 192.168.56.101
  Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                r RIB-failure, S Stale, R Removed
  Origin codes: i - IGP, e - EGP, ? - incomplete

     Network          Next Hop            Metric LocPrf Weight Path
  *> 198.51.100.3/32   203.0.113.2           1             0 2 i  < Path

  Total number of prefixes 1

**Routes learned after routing policy applied:**

.. code-block:: none

  vyos@vos1:~$ show ip bgp
  BGP table version is 0, local router ID is 192.168.56.101
  Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                r RIB-failure, S Stale, R Removed
  Origin codes: i - IGP, e - EGP, ? - incomplete

     Network          Next Hop            Metric LocPrf Weight Path
  *> 198.51.100.3/32   203.0.113.2           1             0 2 2 2 2 i

  Total number of prefixes 1
  vyos@vos1:~$

You now see the longer AS path.


.. _routing-pbr:

###
PBR
###

:abbr:`PBR (Policy-Based Routing)` allowing traffic to be assigned to
different routing tables. Traffic can be matched using standard 5-tuple
matching (source address, destination address, protocol, source port,
destination port).

Transparent Proxy
=================

The following example will show how VyOS can be used to redirect web
traffic to an external transparent proxy:

.. code-block:: none

  set policy route FILTER-WEB rule 1000 destination port 80
  set policy route FILTER-WEB rule 1000 protocol tcp
  set policy route FILTER-WEB rule 1000 set table 100

This creates a route policy called FILTER-WEB with one rule to set the
routing table for matching traffic (TCP port 80) to table ID 100
instead of the default routing table.

To create routing table 100 and add a new default gateway to be used by
traffic matching our route policy:

.. code-block:: none

  set protocols static table 100 route 0.0.0.0/0 next-hop 10.255.0.2

This can be confirmed using the ``show ip route table 100`` operational
command.

Finally, to apply the policy route to ingress traffic on our LAN
interface, we use:

.. code-block:: none

  set interfaces ethernet eth1 policy route FILTER-WEB


Multiple Uplinks
================

VyOS Policy-Based Routing (PBR) works by matching source IP address
ranges and forwarding the traffic using different routing tables.

Routing tables that will be used in this example are:

* ``table 10`` Routing table used for VLAN 10 (192.168.188.0/24)
* ``table 11`` Routing table used for VLAN 11 (192.168.189.0/24)
* ``main`` Routing table used by VyOS and other interfaces not
  participating in PBR

.. figure:: /_static/images/pbr_example_1.png
   :scale: 80 %
   :alt: PBR multiple uplinks

   Policy-Based Routing with multiple ISP uplinks
   (source ./draw.io/pbr_example_1.drawio)

Add default routes for routing ``table 10`` and ``table 11``

.. code-block:: none

  set protocols static table 10 route 0.0.0.0/0 next-hop 192.0.2.1
  set protocols static table 11 route 0.0.0.0/0 next-hop 192.0.2.2

Add policy route matching VLAN source addresses

.. code-block:: none

  set policy route PBR rule 20 set table '10'
  set policy route PBR rule 20 description 'Route VLAN10 traffic to table 10'
  set policy route PBR rule 20 source address '192.168.188.0/24'

  set policy route PBR rule 30 set table '11'
  set policy route PBR rule 30 description 'Route VLAN11 traffic to table 11'
  set policy route PBR rule 30 source address '192.168.189.0/24'

Apply routing policy to **inbound** direction of out VLAN interfaces

.. code-block:: none

  set interfaces ethernet eth0 vif 10 policy route 'PBR'
  set interfaces ethernet eth0 vif 11 policy route 'PBR'


**OPTIONAL:** Exclude Inter-VLAN traffic (between VLAN10 and VLAN11)
from PBR

.. code-block:: none

  set policy route PBR rule 10 description 'VLAN10 <-> VLAN11 shortcut'
  set policy route PBR rule 10 destination address '192.168.188.0/24'
  set policy route PBR rule 10 destination address '192.168.189.0/24'
  set policy route PBR rule 10 set table 'main'

These commands allow the VLAN10 and VLAN20 hosts to communicate with
each other using the main routing table.

Local route
===========

The following example allows VyOS to use :abbr:`PBR (Policy-Based Routing)`
for traffic, which originated from the router itself. That solution for multiple
ISP's and VyOS router will respond from the same interface that the packet was
received. Also, it used, if we want that one VPN tunnel to be through one
provider, and the second through another.

* ``203.0.113.254`` IP addreess on VyOS eth1 from ISP1
* ``192.168.2.254`` IP addreess on VyOS eth2 from ISP2
* ``table 10`` Routing table used for ISP1
* ``table 11`` Routing table used for ISP2


.. code-block:: none

  set policy local-route rule 101 set table '10'
  set policy local-route rule 101 source '203.0.113.254'
  set policy local-route rule 102 set table '11'
  set policy local-route rule 102 source '192.0.2.254'
  set protocols static table 10 route 0.0.0.0/0 next-hop '203.0.113.1'
  set protocols static table 11 route 0.0.0.0/0 next-hop '192.0.2.2'

Add multiple source IP in one rule with same priority

.. code-block:: none

  set policy local-route rule 101 set table '10'
  set policy local-route rule 101 source '203.0.113.254'
  set policy local-route rule 101 source '203.0.113.253'
  set policy local-route rule 101 source '198.51.100.0/24'