OSPF route summarization configuration example
Network requirements
As shown in Figure 26:
Configure OSPF on Switch A and Switch B in AS 200.
Configure OSPF on Switch C, Switch D, and Switch E in AS 100.
Configure an EBGP connection between Switch B and Switch C. Configure Switch B and Switch C to redistribute OSPF routes and direct routes into BGP and BGP routes into OSPF.
Configure Switch B to advertise only summary route 10.0.0.0/8 to Switch A.
Figure 26: Network diagram
Configuration procedure
Configure IP addresses for interfaces. (Details not shown.)
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view [SwitchA] router id 11.2.1.2 [SwitchA] ospf [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit [SwitchA-ospf-1] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] router id 11.2.1.1 [SwitchB] ospf [SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit [SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view [SwitchC] router id 11.1.1.2 [SwitchC] ospf [SwitchC-ospf-1] area 0 [SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] quit [SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] router id 10.3.1.1 [SwitchD] ospf [SwitchD-ospf-1] area 0 [SwitchD-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.0] network 10.3.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.0] quit [SwitchD-ospf-1] quit
# Configure Switch E.
<SwitchE> system-view [SwitchE] router id 10.4.1.1 [SwitchE] ospf [SwitchE-ospf-1] area 0 [SwitchE-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchE-ospf-1-area-0.0.0.0] network 10.4.1.0 0.0.0.255 [SwitchE-ospf-1-area-0.0.0.0] quit [SwitchE-ospf-1] quit
Configure BGP to redistribute OSPF routes and direct routes:
# Configure Switch B.
[SwitchB] bgp 200 [SwitchB-bgp] peer 11.1.1.2 as 100 [SwitchB-bgp] address-family ipv4 unicast [SwitchB-bgp-ipv4] import-route ospf [SwitchB-bgp-ipv4] import-route direct [SwitchB-bgp ipv4] quit [SwitchB-bgp] quit
# Configure Switch C.
[SwitchC] bgp 100 [SwitchC-bgp] peer 11.1.1.1 as 200 [SwitchC-bgp] address-family ipv4 unicast [SwitchC-bgp-ipv4] import-route ospf [SwitchC-bgp-ipv4]import-route direct [SwitchC-bgp-ipv4] quit [SwitchC-bgp] quit
Configure Switch B and Switch C to redistribute BGP routes into OSPF:
# Configure OSPF to redistribute routes from BGP on Switch B.
[SwitchB] ospf [SwitchB-ospf-1] import-route bgp
# Configure OSPF to redistribute routes from BGP on Switch C.
[SwitchC] ospf [SwitchC-ospf-1] import-route bgp
# Display the OSPF routing table on Switch A.
[SwitchA] display ip routing-table Destinations : 16 Routes : 16 Destination/Mask Proto Pre Cost NextHop Interface 0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0 10.1.1.0/24 O_ASE2 150 1 11.2.1.1 Vlan100 10.2.1.0/24 O_ASE2 150 1 11.2.1.1 Vlan100 10.3.1.0/24 O_ASE2 150 1 11.2.1.1 Vlan100 10.4.1.0/24 O_ASE2 150 1 11.2.1.1 Vlan100 11.2.1.0/24 Direct 0 0 11.2.1.2 Vlan100 11.2.1.0/32 Direct 0 0 11.2.1.2 Vlan100 11.2.1.2/32 Direct 0 0 127.0.0.1 InLoop0 11.2.1.255/32 Direct 0 0 11.2.1.2 Vlan100 127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0 127.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0 127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0 127.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0 224.0.0.0/4 Direct 0 0 0.0.0.0 NULL0 224.0.0.0/24 Direct 0 0 0.0.0.0 NULL0 255.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0Configure route summarization:
# Configure route summarization on Switch B to advertise a summary route 10.0.0.0/8.
[SwitchB-ospf-1] asbr-summary 10.0.0.0 8
# Display the IP routing table on Switch A.
[SwitchA] display ip routing-table Destinations : 13 Routes : 13 Destination/Mask Proto Pre Cost NextHop Interface 0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0 10.0.0.0/8 O_ASE2 150 2 11.2.1.1 Vlan100 11.2.1.0/24 Direct 0 0 11.2.1.2 Vlan100 11.2.1.0/32 Direct 0 0 11.2.1.2 Vlan100 11.2.1.2/32 Direct 0 0 127.0.0.1 InLoop0 11.2.1.255/32 Direct 0 0 11.2.1.2 Vlan100 127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0 127.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0 127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0 127.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0 224.0.0.0/4 Direct 0 0 0.0.0.0 NULL0 224.0.0.0/24 Direct 0 0 0.0.0.0 NULL0 255.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0The output shows that routes 10.1.1.0/24, 10.2.1.0/24, 10.3.1.0/24 and 10.4.1.0/24 are summarized into a single route 10.0.0.0/8.