The Frame Relay configuration is a hub-and-spoke topology. Because Los Angeles is the central hub of the company, it is logical that it is also the network hub. The configuration in Frame Relay would therefore be a point-to-multipoint one. This avoids the DR/BDR election process, because it treats all the PVC links as a collection of point-to-point links, forming adjacencies across each link even though they are not separate point-to-point subinterfaces. Having separate links removes the need for the DR/BDR. This is a good solution if three different companies have a multivendor environment, because it conforms to the RFC standards. Example 7-13 shows a configuration that could be implemented. Example 7-13. Answer to Scenario 7-1 Configuration Question 2 Los Angeles interface serial 0 encapsulation frame-relay ip address 10.255.0.35 255.255.255.248 ip ospf network point-to-multipoint router ospf 100 network 10.0.0.0 0.255.255.255 area 0 San Francisco interface serial 0 encapsulation frame-relay ip address 10.255.0.36 255.255.255.248 ip ospf network point-to-multipoint router ospf 100 network 10.0.0.0 0.255.255.255 area 0 London interface serial 0 encapsulation frame-relay ip address 10.255.0.37 255.255.255.248 ip ospf network point-to-multipoint router ospf 100 network 10.0.0.0 0.255.255.255 area 0 If individual point-to-point networks are chosen , then a separate PVC and IP subnet will be required for the configuration. This is illustrated in Example 7-14. Example 7-14. Answer to Scenario 7-1 Configuration Question 2 Los Angeles interface serial 0 no IP address encapsulation frame-relay interface serial0.1 point-to-point ip address 10.255.0.35 255.255.255.252 frame-relay interface-dlci 21 interface serial0.1 point-to-point ip address 10.255.0.49 255.255.255.252 frame-relay interface-dlci 28 router ospf 100 network 10.0.0.0 0.255.255.255 area 0 San Francisco interface serial 0 no IP address encapsulation frame-relay interface serial0.1 point-to-point ip address 10.255.0.36 255.255.255.252 frame-relay interface-dlci 44 router ospf 100 network 10.0.0.0 0.255.255.255 area 0 London interface serial 0 no IP address encapsulation frame-relay interface serial0.1 point-to-point ip address 10.255.0.50 255.255.255.252 frame-relay interface-dlci 66 router ospf 100 network 10.0.0.0 0.255.255.255 area 0 Note that the Frame Relay cloud is a continuation of Area 0. This is a logical first step; it is advisable to change this configuration when OSPF is being run throughout the organization. When the other sites are up and running OSPF, the Los Angeles site could become another area. This would allow the summarization of routes across the Frame Relay cloud, which would reduce the traffic, cost, and possibility for congestion. |