LAB: BGP Local AS Replace-AS/Dual-AS

- Re-configure R1 to reside in AS 146 as well and act as a routing reflector for R4 and R6.
- All external Autonomous Systems should be unaware of the new AS numbers used by these routers.
- R5 should peer with R4 using the AS number 146.


configuration:

R1:
router bgp 146
neighbor 155.1.146.4 remote-as 146
neighbor 155.1.146.6 remote-as 146
neighbor 155.1.146.4 route-reflector-client
neighbor 155.1.146.6 route-reflector-client
neighbor 155.1.13.3 remote-as 200
neighbor 155.1.13.3 local-as 100 no-prepend replace-as

R4:
router bgp 146
neighbor 155.1.146.1 remote-as 146
neighbor 155.1.45.5 local-as 100 no-prepend replace-as dual-as
neighbor 204.12.1.254 local-as 100 no-prepend replace-as

R5:
router bgp 200
neighbor 155.1.45.4 remote-as 146

R6:
router bgp 146
neighbor 155.1.146.1 remote-as 146
neighbor 155.1.67.7 local-as 100 no-prepend replace-as
neighbor 54.1.1.254 local-as 100 no-prepend replace-as

verification:

Rack1R3# show ip bgp nei
Rack1R3# show ip bgp neighbors 155.1.13.1 rout
Rack1R3# show ip bgp neighbors 155.1.13.1 routes
BGP table version is 155, local router ID is 150.1.3.3
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
*> 28.119.16.0/24   155.1.13.1                             0 100 54 i
*> 28.119.17.0/24   155.1.13.1                             0 100 54 i
*> 112.0.0.0        155.1.13.1                    200      0 100 54 50 60 i
*> 113.0.0.0        155.1.13.1                    200      0 100 54 50 60 i
*> 114.0.0.0        155.1.13.1                             0 100 54 i
*> 115.0.0.0        155.1.13.1                             0 100 54 i
*> 116.0.0.0        155.1.13.1                             0 100 54 i
*> 117.0.0.0        155.1.13.1                             0 100 54 i
*> 118.0.0.0        155.1.13.1                             0 100 54 i
*> 119.0.0.0        155.1.13.1                             0 100 54 i
*> 155.1.0.0        155.1.13.1                             0 100 i
*  222.22.3.0       155.1.13.1                             0 100 300 i

Total number of prefixes 12 

Rack1SW1#
*Mar  1 01:35:03.456: %BGP-3-MAXPFXEXCEED: No. of prefix received from 155.1.37.3 (afi 0): 24 exceed limit 20
Rack1SW1#show ip bgp neighbors 155.1.67.6 routes
BGP table version is 203, local router ID is 150.1.77.77
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
*  0.0.0.0          155.1.67.6                             0 100 200 i
*  2.2.2.0/24       155.1.67.6                             0 100 200 i
*  3.3.3.0/24       155.1.67.6                             0 100 200 i
*  5.5.5.0/24       155.1.67.6                             0 100 200 i
*  10.0.0.0/24      155.1.67.6                             0 100 200 i
*  10.0.0.0/22      155.1.67.6                             0 100 200 i
*  10.0.1.0/24      155.1.67.6                             0 100 200 i
*  10.0.2.0/24      155.1.67.6                             0 100 200 i
*  10.0.3.0/24      155.1.67.6                             0 100 200 i
*> 28.119.16.0/24   155.1.67.6                             0 100 54 i
*> 28.119.17.0/24   155.1.67.6                             0 100 54 i
*> 112.0.0.0        155.1.67.6                             0 100 54 50 60 i
*> 113.0.0.0        155.1.67.6                             0 100 54 50 60 i
*> 114.0.0.0        155.1.67.6                             0 100 54 i
*> 115.0.0.0        155.1.67.6                             0 100 54 i
*> 116.0.0.0        155.1.67.6                             0 100 54 i
*> 117.0.0.0        155.1.67.6                             0 100 54 i
*> 118.0.0.0        155.1.67.6                             0 100 54 i
*> 119.0.0.0        155.1.67.6                             0 100 54 i
*> 155.1.0.0        155.1.67.6               0             0 100 i
*  222.22.0.0       155.1.67.6                             0 100 200 i
*  222.22.1.0       155.1.67.6                             0 100 200 i

@ R5

Rack1R5#show ip bgp neighbors 155.1.45.4 routes
BGP table version is 223, local router ID is 150.1.5.5
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
*> 28.119.16.0/24   155.1.45.4                    200      0 146 54 i
*> 28.119.17.0/24   155.1.45.4                    200      0 146 54 i
*  112.0.0.0        155.1.45.4                             0 146 54 50 60 i
*  113.0.0.0        155.1.45.4                             0 146 54 50 60 i
*> 114.0.0.0        155.1.45.4                    200      0 146 54 i
*> 115.0.0.0        155.1.45.4                    200      0 146 54 i
*> 116.0.0.0        155.1.45.4                    200      0 146 54 i
*> 117.0.0.0        155.1.45.4                    200      0 146 54 i
*> 118.0.0.0        155.1.45.4                    200      0 146 54 i
*> 119.0.0.0        155.1.45.4                    200      0 146 54 i
*> 155.1.0.0        155.1.45.4               0             0 146 i
*  222.22.3.0       155.1.45.4                             0 146 300 i

changing R5 BGP configuration to use 100 instead.

Rack1R5#show ip bgp neighbors 155.1.45.4 routes
BGP table version is 275, local router ID is 150.1.5.5
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
*> 28.119.16.0/24   155.1.45.4                    200      0 100 54 i
*> 28.119.17.0/24   155.1.45.4                    200      0 100 54 i
*  112.0.0.0        155.1.45.4                             0 100 54 50 60 i
*  113.0.0.0        155.1.45.4                             0 100 54 50 60 i
*> 114.0.0.0        155.1.45.4                    200      0 100 54 i
*> 115.0.0.0        155.1.45.4                    200      0 100 54 i
*> 116.0.0.0        155.1.45.4                    200      0 100 54 i
*> 117.0.0.0        155.1.45.4                    200      0 100 54 i
*> 118.0.0.0        155.1.45.4                    200      0 100 54 i
*> 119.0.0.0        155.1.45.4                    200      0 100 54 i
*> 155.1.0.0        155.1.45.4               0             0 100 i
*  222.22.3.0       155.1.45.4                             0 100 300 i

Total number of prefixes 12