250Origin : igpAttribute value : MED 0, localpref 100, pref-val 0, pre 255State : valid, internal, best,Not advertised to any peers yetThe output information shows the following:• Switch F can send route information to Switch B and Switch C through the confederation byestablishing only an eBGP connection with Switch A.• Switch B and Switch D are in the same confederation, but belong to different sub ASs. They obtainexternal route information from Switch A and generate the same BGP route entries; it seems like theyreside in the same AS although they have no direct connection in between.BGP path selection configurationNetwork requirementsIn Figure 96, all switches run BGP. Between Switch A and Switch B, and between Switch A and SwitchC are eBGP connections. Between Switch B and Switch D, and between Switch D and Switch C are iBGPconnections. OSPF is the IGP protocol in AS 200.Configure routing policies, making Switch D use the route 1.0.0.0/8 from Switch C as the optimal.Figure 96 Network diagramDevice Interface IP address Device Interface IP addressSwitch A Vlan-int101 1.0.0.0/8 Switch D Vlan-int400 195.1.1.1/24Vlan-int100 192.1.1.1/24 Vlan-int300 194.1.1.1/24Vlan-int200 193.1.1.1/24 Switch C Vlan-int400 195.1.1.2/24Switch B Vlan-int100 192.1.1.2/24 Vlan-int200 193.1.1.2/24Vlan-int300 194.1.1.2/24Configuration procedure1. Configure IP addresses for interfaces. (Details not shown)2. Configure OSPF on Switch B, C, and D.# Configure Switch B. system-view[SwitchB] ospf[SwitchB-ospf] area 0[SwitchB-ospf-1-area-0.0.0.0] network 192.1.1.0 0.0.0.255[SwitchB-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255
