3com WX3000 Manuel D’Utilisation

 

1-4 

each routing protocol (including static routes) is assigned a priority. The route found by the routing 

protocol with the highest priority is preferred.  

The following table lists some routing protocols and the default priorities for routes found by them: 

Table 1-1 Routing protocols and priorities of their default route 

DIRECT 

0 

OSPF 10 

STATIC 60 

RIP 100 

OSPF ASE 

150 

OSPF NSSA 

150 

UNKNOWN 255 

 

z 

The smaller the priority value, the higher the priority. 

z 

The priority for a direct route is always 0, which you cannot change. Any other type of routes can 

have their priorities manually configured. 

z 

Each static route can be configured with a different priority. 

 

A given routing protocol may find several routes with the same metric to the same destination, and if this 

protocol has the highest priority among all the active protocols, these routes will be considered valid and 

are used to forward packets, thus achieving load sharing. 

You can configure multiple routes to the same destination, expecting the one with the highest priority to 

be the primary route and all the rest backup routes. 

Route backup can help improve network reliability. Automatic switching can happen between the 

primary route and a backup route. 

Under normal circumstances, packets are forwarded through the primary route. When the primary route 

goes down, the route with the highest priority among the backup routes is selected to forward packets. 

When the primary route recovers, the route selection process is performed again and the primary route 

is selected again to forward packets. 

As different routing protocols use different algorithms to calculate routes, they may discover different 

routes. In a large network with multiple routing protocols, it is required for routing protocols to share their