3Com WX3000 Load Sharing and Route Backup, Routing Information Sharing, Load sharing

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 1-1Routing protocols and priorities of their default route

Routing approach	Priority
DIRECT	0
OSPF	10
STATIC	60
RIP	100
OSPF ASE	150
OSPF NSSA	150
UNKNOWN	255

z

z

z

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.

Load Sharing and Route Backup

Load sharing

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.

Route backup

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.

Routing Information Sharing

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

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