HP VPN Firewall Appliances Appendix Protocol Reference

3
Route t
yp
e Preference
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, IS-IS, IPv6 IS-IS, BGP, and IPv6 BGP 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.
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.