DELL 8132 ユーザーズマニュアル

OSPF Commands

Normally, OSPF select routes in the following order:

• Local
• Static
• Intra-area
• Inter-area
• External
• RIP

PowerConnect OSPF allows the administrator to change the preference for 

selecting intra, inter, and external routes according to the following rules:

External route preferences apply to all ospf external routes like type1, 

type2, nssa-type1, nssa-type2 equally.

Multiple route types may be configured with equal preference values.

Configuring a route preference of 255 makes the route ineligible to be 

selected as the best route to its destination. That is, a route type with 

a preference of 255 shall never be used for forwarding.

The RIP preference is not used in IPv6 routing.

A device running the IP routing protocol OSPF maintains multiple equal-cost 

routes to all destinations. The multiple routes are of the same type (intra-

area, inter-area, type 1 external or type 2 external), cost, and have the same 

associated area. However, each route is defined by a separate advertising 

router and next hop.
With ECMP, a device forwards traffic to a specified destination through 

multiple paths thereby taking advantage of the bandwidth of both links.
ECMP routes are configured statically or learned dynamically as follows:

• Configured Statically: If an operator configures multiple static routes to 

the exact same destination but with different next hops, those routes are 

treated as a single route with two next hops. 

2CSPC4.X8100-SWUM102.book  Page 1196  Friday, March 15, 2013  8:56 AM