H3C Technologies H3C S3100 Series Switches - Manual (Page 266)

Operation Manual – Routing Protocol
H3C S3100-52P Ethernet Switch Chapter 1 IP Routing Protocol Overview
1-5
In the table, “0” is used for directly connected routes, and “255” is used for routes from
untrusted sources.
Table 1-1
Routing protocols and corresponding route preferences
Routing protocol or route type
Preference of the corresponding
route
DIRECT 0
OSPF 10
STATIC 60
RIP 100
OSPF ASE
150
OSPF NSSA 150
UNKNOWN 255
Except for direct routing, you can manually configure the preferences of various
dynamic routing protocols as required. In addition, you can configure different
preferences for different static routes.
1.2.2 Traffic Sharing and Route Backup
I. Traffic sharing
The S3100-52P support multi-route mode, allowing the configuration of multiple routes
that reach the same destination and have the same preference. The same destination
can be reached through multiple different routes, whose preferences are equal. When
there is no route with a higher preference to the same destination, the multiple routes
will be adopted. Then, the packets destined for the same destination will be forwarded
through these routes in turn to implement traffic sharing.
II. Route backup
The S3100-52P support route backup. When the primary route fails, the system
automatically switches to a backup route to improve network reliability.
To achieve route backup, you can configure multiple routes to the same destination
according to actual situation. One of the routes has the highest preference and is called
primary route. The other routes have descending preferences and are called backup
routes. Normally, the router sends data through the primary route. When line failure
occurs on the primary route, the primary route will hide itself and the router will choose
the one whose preference is the highest among the remaining backup routes as the
path to send data. In this way, the switchover from the primary route to a backup route
is implemented. When the primary route recovers, the router will restore it and re-select
a route. And, as the primary route has the highest preference, the router will choose the