Dynamic Routing Protocols; Route Preference - HPE FlexNetwork HSR6800 Configuration Manual

•
Pre—Preference of the route. Among routes to the same destination, the one with the highest
preference is optimal.
•
Cost—When multiple routes to a destination have the same preference, the one with the
smallest cost becomes the optimal route.
•
NextHop—Next hop.
•
Interface—Output interface.

Dynamic routing protocols

Dynamic routing protocols dynamically collect and report reachability information to adapt to
topology changes. They are suitable for large networks.
Compared with static routing, dynamic routing protocols require more resources, and are
complicated to configure.
Dynamic routing protocols can be classified by different criteria, as shown in
Table 2 Categories of dynamic routing protocols
Criterion
Optional scope
Routing algorithm
Destination address
type
IP version
NOTE:
An AS refers to a group of routers that use the same routing policy and work under the same
administration.

Route preference

Routing protocols (including static and direct routing) each by default have a preference. If they find
multiple routes to the same destination, the router selects the route with the highest preference as
the optimal route.
The preference of a direct route is always 0 and cannot be changed. You can configure a preference
for each static route and each dynamic routing protocol as required. The following table lists the
route types and their default preferences. The smaller the value, the higher the preference.
Table 3 Route types and their default route preferences
Routing type
Direct route
OSPF
Categories
•
Interior gateway protocols (IGPs)—Work within an autonomous system
(AS). Examples include RIP, OSPF, and IS-IS.
•
Exterior gateway protocols (EGPs)—Work between ASs. The most popular
one is BGP.
•
Distance-vector protocols—RIP and BGP. BGP is also considered a
path-vector protocol.
•
Link-state protocols—OSPF and IS-IS.
•
Unicast routing protocols—RIP, OSPF, BGP, and IS-IS.
•
Multicast routing protocols—PIM-SM and PIM-DM (For more information,
see IP Multicast Configuration Guide).
•
IPv4 routing protocols—RIP, OSPF, BGP, and IS-IS.
•
IPv6 routing protocols—RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS.
2
Preference
0
10
Table 2: