How to configure BGP route summarization on Cisco routers?

 

BGP Route Summarization

 

The BGP route summarization basically used to decrease the uses of bandwidth to optimize the network performance and also manage the size of routing table. For example if you are trying to advertise four routes 192.1.17.0/24, 192.1.18.0/24, 192.1.19.0/24 and 192.1.20.0/24 from router C to router B then the only summarized address as 192.1.16.0 255.255.248.0 will be advertised in the update packet.

 

 

RUNNING RIP ON ROUTER-A

 

A(config)# router rip

A(config-router)# network 200.100.50.0

A(config-router)# network 1.0.0.0

 

 

RUNNING EBGP ON ROUTER-A

 

A(config)# router  bgp 10

A(config-router)# no synchronization

A(config-router)# neighbor 1.1.1.2 remote-as 20

A(config-router)# neighbor 4.1.1.1 remote-as 20

A(config-router)# network200.100.50.0

 

 

RUNNING EBGP ON ROUTER-B

 

B(config)# router bgp 20

B(config-router)# no synchronization

B(config-router)# neighbor 1.1.1.1remote-as 10

 

RUNNING EBGP ON ROUTER-D

 

D(config)# router bgp 20

D(config-router)# no synchronization

D(config-router)# neighbor 4.1.1.2 remote-as 10

 

RUNNING OSPF ON ROUTER-B

 

B(config)# router ospf 1

B(config-router)# network 2.0.0.0 0.255.255.255  area 0

B(config-router)# network 1.0.0.0 0.255.255.255  area 0

 

 

RUNNING OSPF ON ROUTER-C

 

C(config)# router ospf 1

C(config-router)# network 2.0.0.0 0.255.255.255 area 0

C(config-router)# network 3.0.0.0 0.255.255.255 area 0

 

RUNNING OSPF ON ROUTER-D

 

D(config)# router ospf 1

D(config-router)# network 3.0.0.0 0.255.255.255 area 0

D(config-router)# network 4.0.0.0 0.255.255.255 area 0

 

RUNNING IBGP ON ROUTER-B

 

B(config)# router bgp 20

B(config-router)# no synchronization

B(config-router)# neighbor 4.1.1.1remote-as 20

B(config-router)# neighbor 2.1.1.2remote-as 20

 

RUNNING IBGP ON ROUTER-C

C(config)# router bgp 20

C(config-router)# no synchronization

C(config-router)# neighbor 2.1.1.1remote-as 20

C(config-router)# neighbor 3.1.1.2remote-as 20

 

RUNNING IBGP ON ROUTER-D

 

D(config)# router bgp 20

D(config-router)# no synchronization

D(config-router)# neighbor 3.1.1.1remote-as 20

D(config-router)# neighbor 2.1.1.1remote-as 20

 

 

 

DEFINING 4 STATIC ROUTES ON ROUTER-A

 

A(config)# ip route 192.1.18.0 255.255.255.0 null 0

A(config)# ip route 192.1.19.0 255.255.255.0 null 0

A(config)# ip route 192.1.20.0 255.255.255.0 null 0

REDISTRIBUTION OF STATIC ROUTES INTO BGP 10 – ROUTER-A

 

A(config)# router bgp 10

 

A(config-router)# redistribute static

 

C# show ip bgp

 

 

CREATING SUMMARY OF STATIC ROUTES

 

A(config)# router bgp 10

A(config-router)# aggregate-address 192.1.16.0 255.255.218.0 summary-only

 

C# show ip bgp

 

 

 

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