R21xx-HP FlexFabric 11900 Layer 3 IP Routing Configuration Guide

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10.5.1.0/24 17 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.1.1.0/24 5 Inter 10.2.1.1 10.2.1.1 0.0.0.1
Total Nets: 6
Intra Area: 2 Inter Area: 4 ASE: 0 NSSA: 0
After the area where Switch C resides is configured as a stub area, a default route takes the place
of the AS external route.
# Configure the area as a totally stub area by filtering Type-3 LSAs out of the stub area.
[SwitchA] ospf
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] stub no-summary
[SwitchA-ospf-1-area-0.0.0.1] quit
# Display OSPF routing information on Switch C.
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
0.0.0.0/0 4 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.2.1.0/24 3 Transit 10.2.1.2 10.4.1.1 0.0.0.1
10.4.1.0/24 3 Stub 10.4.1.1 10.4.1.1 0.0.0.1
Total Nets: 3
Intra Area: 2 Inter Area: 1 ASE: 0 NSSA: 0
After this configuration, inter-area routes are removed, and only one external route (a default route)
exists.
Configuring an OSPF NSSA area
Network requirements
• Configure OSPF on all switches and split AS into three areas.
• Configure Switch A and Switch B as ABRs to forward routing information between areas.
• Configure Area 1 as an NSSA area and configure Switch C as an ASBR to redistribute static routes
into the AS.