LAB:BGP Bestpath Selection: Always compare MED

- Create a new Loopback1 interface on both R6 and SW3 with the IP address 1.2.3.4/32 and advertise it into BGP on both R6 and SW3.
- Using just the MED attribute configure the network so that traffic from AS 200 going to this prefix is always received by SW3.

configuration:

R1:
ip prefix-list LOOPBACK1 permit 1.2.3.4/32
!
route-map TO_R3 permit 10
match ip address prefix-list LOOPBACK1
set metric 1000
!
route-map TO_R3 permit 100
!
router bgp 100
neighbor 155.1.13.3 route-map TO_R3 out

R2:
router bgp 200
bgp always-compare-med
R3:
router bgp 200
bgp always-compare-med

R4:
ip prefix-list LOOPBACK1 permit 1.2.3.4/32
!

route-map TO_R5 permit 10
match ip address prefix-list LOOPBACK1
set metric 1000
!
route-map TO_R5 permit 100
!
router bgp 100
neighbor 155.1.45.5 route-map TO_R5 out
 

R5:
router bgp 200
bgp always-compare-med

SW1:
ip prefix-list LOOPBACK1 permit 1.2.3.4/32
!
route-map TO_R3 permit 10
match ip address prefix-list LOOPBACK1
set metric 100
!
route-map TO_R3 permit 100
!
router bgp 300
neighbor 155.1.37.3 route-map TO_R3 out

SW2:
router bgp 200
bgp always-compare-med
SW3:
interface Loopback1
ip address 1.2.3.4 255.255.255.255
!
router bgp 300
network 1.2.3.4 mask 255.255.255.255

SW4:
router bgp 200
bgp always-compare-med

verification:

Rack1R3#show ip bgp 1.2.3.4
BGP routing table entry for 1.2.3.4/32, version 42
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Flag: 0x820
  Advertised to update-groups:
     1          2          3        
  100
    155.1.13.1 from 155.1.13.1 (150.1.1.1)
      Origin IGP, metric 1000, localpref 100, valid, external
  300
    155.1.37.7 from 155.1.37.7 (150.1.7.7)
      Origin IGP, metric 100, localpref 100, valid, external, best

BGP routing table entry for 1.2.3.4/32, version 43
Paths: (2 available, best #2, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1          3        
  100
    155.1.45.4 from 155.1.45.4 (150.1.4.4)
      Origin IGP, metric 1000, localpref 100, valid, external
  300
    155.1.37.7 (metric 2172416) from 155.1.23.3 (150.1.3.3)
      Origin IGP, metric 100, localpref 100, valid, internal, best

Rack1R2#show ip bgp 1.2.3.4
BGP routing table entry for 1.2.3.4/32, version 50
Paths: (2 available, best #2, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1        
  300
    155.1.37.7 (metric 2172416) from 155.1.0.5 (150.1.5.5)
      Origin IGP, metric 100, localpref 100, valid, internal
      Originator: 150.1.3.3, Cluster list: 150.1.5.5
  300
    155.1.37.7 (metric 2172416) from 155.1.23.3 (150.1.3.3)
      Origin IGP, metric 100, localpref 100, valid, internal, best