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Route type Preference
Unicast static route 60
RIP 100
OSPF ASE 150
OSPF NSSA 150
IBGP 255
EBGP 255
Unknown (route from an untrusted source) 256
Load sharing
A routing protocol might find multiple optimal equal-cost routes to the same destination. You can use
these routes to implement equal-cost multi-path (ECMP) load sharing.
Static routing, IPv6 static routing, RIP, RIPng, OSPF, OSPFv3, BGP, IPv6 BGP, IS-IS, and IPv6 IS-IS
support ECMP load sharing.
Route backup
Route backup can improve network availability. Among multiple routes to the same destination, the
route with the highest priority is the primary route and others are secondary routes.
The router forwards matching packets through the primary route. When the primary route fails, the
route with the highest preference among the secondary routes is selected to forward packets. When
the primary route recovers, the router uses it to forward packets.
Route recursion
To use a route that has an indirectly connected next hop, a router must perform route recursion to
find the output interface to reach the next hop.
The RIB records and saves route recursion information, including brief information about related
routes, recursive paths, and recursion depth.
Route redistribution
Route redistribution enables routing protocols to learn routing information from each other. A
dynamic routing protocol can redistribute routes from other routing protocols, including direct and
static routing. For more information, see the respective chapters on those routing protocols in this
configuration guide.
The RIB records redistribution relationships of routing protocols.
Extension attribute redistribution
Extension attribute redistribution enables routing protocols to learn route extension attributes from
each other, including BGP extended community attributes, OSPF area IDs, route types, and router
IDs.
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