BGP Lab 7 Injecting routes to BGP (CCNP Level)

Download Lab: GNS3

Image requirements:
 Cisco IOSv        (vios-adventerprisek9-m.vmdk.SPA.156-2.T)

As you might have learned from your CCNP route course, you know that routes get populated into the BGP table from the IP routing table, in this lab, you will perform configurations of different methods of injecting routes into BGP table. Routers in this topology already have been preconfigured with loopback interfaces to simulate subnets, also there is the static route on each router to the null0 for the purpose of simulation of the entire network of the autonomous system. For example, AS104 has network This lab assumes that you already understand the prefix-list and route-map.

Lab tasks:

Method1: Injecting routes using network statements.

1. Router ISP1 will advertise its static route for the entire AS101 using network command.

2. Router ISP2 will advertise its static route for the entire AS102 using network command.

3. Router ISP3 will advertise its static route for the entire AS103 using network command.

Configuration example:
ISP1(config)# router bgp 101
ISP1(config-router)# network mask
ISP1(config-router)# end

Method2: Injecting routes by using redistribution. This will be performed on ISP4 only.

1. Verify connected routes.

2. Create the ip prefix-list to identify connected routes, named LOCAL_PREFIXES

3. Configure route-map LC_PRX and match the ip prefix-list from step 2.

4. Redistribute connected subnets into BGP using route-map defined in step 3.

5. Verify that local prefixes have been advertised.

Configuration example:
ISP4(config)# ip prefix-list LOCAL_PREFIXES permit ge 24 le 24
ISP4(config)# route-map LC_PRX permit 10
ISP4(config-route-map)# match ip address prefix-list LOCAL_PREFIXES
ISP4(config-route-map)# exit
ISP4(config)# router bgp 104
ISP4(config-router)#redistribute connected route-map LC_PRX

ISP4# show ip bgp

Advertise the summary network:

1.  Configure ISP4 to advertise the summary network using aggregate-address command.

2. Do soft outbound bgp reset for all ISP4 neighbors to propagate changes faster.

3. Verify that ISP4 advertises the only summary network.

Configuration example:
ISP4(config)# router bgp 104
ISP4(config-router)# aggregate-address summary-only
ISP4(config-router)# end
ISP4# clear ip bgp * soft out

Verification commands for eBGP-learned routes:

List possible routes, per prefix:
ER2# show  ip bgp

List routes learned from one neighbor before any inbound filtering is applied:
ER2# show  ip bgp neighbors received-routes

List routes learned from a specific neighbor that passed any inbound filters:
ER2# show  ip bgp  neighbors routes

Lists routes advertised to a neighbor after applying outbound filtering:
ER2#show  ip bgp neighbors advertised-routes

List possible default routes:
ER2# show  ip bgp

List the number of prefixes learned per neighbor:
ER# show ip bgp summary




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