Task 3: Configuring BGP Aggregation

Your ISP has requested that you provide only summarized prefixes for your address range 197.1.0.0. However, because of diagnostics needs, you still need to announce the network 197.1.8.0.

Procedure:
Complete these steps:
Step 1  Log in to the router Good; verify that the ISP sees all your individual loopback networks.

Good#show ip bgp
BGP table version is 39, local router ID is 199.199.199.199
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
*> 197.1.1.0        192.168.20.1             0             0 1 i
*> 197.1.2.1/32     192.168.20.1            65             0 1 i
*> 197.1.3.1/32     192.168.20.1            65             0 1 i
   Network          Next Hop            Metric LocPrf Weight Path
*> 197.1.4.1/32     192.168.20.1           129             0 1 i
*> 197.1.5.1/32     192.168.20.1           129             0 1 i
*> 197.1.6.1/32     192.168.20.1           193             0 1 i
*> 197.1.7.1/32     192.168.20.1           193             0 1 i
*> 197.1.8.0        192.168.20.1             0                0 1 i

Step 2 Use the aggregate command in your BGP process to aggregate the 197.1.1.0 network as requested  by your ISP.


WG1R1(config)#router bgp 1
WG1R1(config-router)#aggregate-address 197.1.0.0 255.255.0.0 summary-only
WG1R1(config-router)#aggregate-address 197.1.8.0 255.255.248.0 summary-only
WG1R1(config-router)#end

Verification

•  all the loopback addresses should be suppressed.

 WG1R1#show ip bgp
BGP table version is 47, local router ID is 197.1.8.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
s> 197.1.1.0        0.0.0.0                  0         32768 i
s> 197.1.2.1/32     192.168.1.2             65         32768 i
s> 197.1.3.1/32     192.168.1.2             65         32768 i
s> 197.1.4.1/32     192.168.1.2            129         32768 i
s> 197.1.5.1/32     192.168.1.2            129         32768 i
s> 197.1.6.1/32     192.168.1.2            193         32768 i
s> 197.1.7.1/32     192.168.1.2            193         32768 i
s> 197.1.8.0        0.0.0.0                  0         32768 i

• on router Good suppressed networks should not be visible.

*> 197.1.0.0/16     192.168.20.1             0             0 1 i
*> 197.1.8.0/21     192.168.20.1             0             0 1 i

•  View the detailed information of the aggregated ip prefixes.
  

Good>show ip bgp 197.1.0.0
BGP routing table entry for 197.1.0.0/16, version 40
Paths: (1 available, best #1, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1
  1, (aggregated by 1 197.1.8.1)
    192.168.20.1 from 192.168.20.1 (197.1.8.1)
      Origin IGP, metric 0, localpref 100, valid, external, atomic-aggregate, best
Good>show ip bgp 197.1.8.0
BGP routing table entry for 197.1.8.0/21, version 49
Paths: (1 available, best #1, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1
  1, (aggregated by 1 197.1.8.1)
    192.168.20.1 from 192.168.20.1 (197.1.8.1)
      Origin IGP, metric 0, localpref 100, valid, external, atomic-aggregate, best