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diff --git a/docs/routing/policy.rst b/docs/routing/policy.rst new file mode 100644 index 00000000..4eeb40d6 --- /dev/null +++ b/docs/routing/policy.rst @@ -0,0 +1,65 @@ +.. 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 1 neighbor 203.0.113.2 address-family ipv4-unicast route-map import 'setmet' + set protocols bgp 1 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:~$ sho ip b + 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. |