3
Route type Preference
Multicast static route 1
OSPF 10
IS-IS 15
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 may 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
outgoing interface to reach the next hop.
Route redistribution
Route redistribution enables routing protocols to learn route 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.
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