Routing Preference; Load Sharing; Route Backup - HP MSR2000 series Configuration Manual

NOTE:
An AS refers to a group of routers sharing the same routing policy and working under the same
administration.

Routing preference

Different routing protocols can find different routes to the same destination. However, not all of those
routes are optimal. For route selection, routing protocols, direct routes, and static routes are assigned
different preferences. The route with the highest preference is preferred.
The preference of a direct route is always 0 and cannot be changed. You can manually configure
preferences for any other route type. Each static route can be configured with a different preference. The
following table lists the types of routes and the default preferences. The smaller the preference value, the
higher the preference.
Table 3 Route types and their default route preferences
Routing approach
Direct route
OSPF
IS-IS
Static route
RIP
OSPF ASE
OSPF NSSA
IBGP
EBGP
Unknown (route from an untrusted source)

Load sharing

A routing protocol can be configured with multiple equal-cost routes to the same destination. These routes
have the same preference and will all be used to accomplish load sharing if there is no route with a
higher preference available.
Static routing/IPv6 static routing, RIP/RIPng, OSPF/OSPFv3, BGP/IPv6 BGP, and IS-IS/IPv6 IS-IS
supports ECMP load sharing.
The load sharing function is available only on the A5500 EI Switch series.

Route backup

Route backup can improve network availability. Among multiple routes to the same destination, the route
with the highest preference is the main route and all others are backup routes.
Preference
0
10
15
60
100
150
150
255
255
256
3