.. _zebra-vrf:
+Administrative Distance
+=======================
+
+Administrative distance allows FRR to make decisions about what routes
+should be installed in the rib based upon the originating protocol.
+The lowest Admin Distance is the route selected. This is purely a
+subjective decision about ordering and care has been taken to choose
+the same distances that other routing suites have choosen.
+
++------------+-----------+
+| Protocol | Distance |
++------------+-----------+
+| System | 0 |
++------------+-----------+
+| Kernel | 0 |
++------------+-----------+
+| Connect | 0 |
++------------+-----------+
+| Static | 1 |
++------------+-----------+
+| NHRP | 10 |
++------------+-----------+
+| EBGP | 20 |
++------------+-----------+
+| EIGRP | 90 |
++------------+-----------+
+| BABEL | 100 |
++------------+-----------+
+| OSPF | 110 |
++------------+-----------+
+| ISIS | 115 |
++------------+-----------+
+| OPENFABRIC | 115 |
++------------+-----------+
+| RIP | 120 |
++------------+-----------+
+| Table | 150 |
++------------+-----------+
+| SHARP | 150 |
++------------+-----------+
+| IBGP | 200 |
++------------+-----------+
+| PBR | 200 |
++------------+-----------+
+
+An admin distance of 255 indicates to Zebra that the route should not be
+installed into the Data Plane. Additionally routes with an admin distance
+of 255 will not be redistributed.
+
+Zebra does treat Kernel routes as special case for the purposes of Admin
+Distance. Upon learning about a route that is not originated by FRR
+we read the metric value as a uint32_t. The top byte of the value
+is interpreted as the Administrative Distance and the low three bytes
+are read in as the metric. This special case is to facilitate VRF
+default routes.
+
Virtual Routing and Forwarding
==============================