Load sharing, Route backup, Route recursion – H3C Technologies H3C S5560 Series Switches User Manual

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Table 3 Route types and default route preferences

Route type

Preference

Direct route

0

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 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.

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