Load Sharing; Route Backup; Route Recursion; Route Redistribution - HP HPE FlexNetwork 7500 series Configuration Manual

Route type
RIP
OSPF ASE
OSPF NSSA
IBGP
EBGP
Unknown (route from an untrusted source)

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 BGP, static, or RIP route that has an indirectly connected next hop, a router must perform
route recursion to find the output interface to reach the next hop.
Link-state routing protocols, such as OSPF and IS-IS, do not need route recursion, because they
obtain directly connected next hops through route calculation.
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.
Preference
100
150
150
255
255
256
3