3com S7906E Manuel De Montage

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1-5 
Routing approach 
Priority 
OSPF NSSA 
150 
IBGP 255 
EBGP 255 
UNKNOWN 256 
 
 
The smaller the priority value, the higher the priority. 
The priority for a direct route is always 0, which you cannot change. Any other type of routes can 
have their priorities manually configured. 
Each static route can be configured with a different priority. 
IPv4 and IPv6 routes have their own respective routing tables. 
 
Load Balancing and Route Backup 
Load Balancing 
In multi-route mode, a routing protocol can be configured with multiple equal-cost routes to the same 
destination. These routes have the same priority and will all be used to accomplish load balancing if 
there is no route with a higher priority available. 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 routes for load balancing. 
 
 
The number of routes for load balancing is 8. 
In current implementations, routing protocols supporting load balancing are static routing, RIP, 
OSPF, BGP, and IS-IS. 
 
Route backup 
Route backup can help improve network reliability. With route backup, you can configure multiple routes 
to the same destination, expecting the one with the highest priority to be the main route and all the rest 
backup routes. 
Under normal circumstances, packets are forwarded through the main route. When the main route goes 
down, the route with the highest priority among the backup routes is selected to forward packets. When 
the main route recovers, the route selection process is performed again and the main route is selected 
again to forward packets.