*You may need to remove or alter parts of configuration from the previous task. 

1. Routers in AS12 should send traffic towards AS8 using link R3-R7 as primary option, R3-R6 as         secondary option and R1-R5 as last resort. 

2. AS67 should be able to signal to AS12 the preferred entry point (R7 or R6), for network 67.0/16.       Use  an optional nontransitive path attribute to complete this task. 

3. AS67 and AS5 are the service-providers for AS12. AS67 and AS5 should not use AS12 to reach         any networks, except networks owned by AS12. 

4. AS5, AS8 and AS67 shall use link R3-R7  to reach AS12 as primary option. If this link is                   unavailable, use link R3-R6. Use link R1-R5 as last resort. Use a well-known mandatory path             attribute to complete this requirement. 

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This task requires understanding of best-path selection using AS-PATH, Local-Preference & MED attributes. It also requires understanding of well-known communities.

Requirement #1 - change the inbound policy on R3 and R1 from the previous task, to only set local-preference for prefix 8.0/16. 
Requirement #2 - routers R6 and R7 should set a MED attribute when advertising prefix 67.0/16 to AS12. Lower MED value is preferred. 
Requirement #3 - to prevent the "client" autonomous-system from being used as a transit, service-providers should set a well-known "no-export" community to prefixes advertised to the client. 
Requirement #4 - configure outbound policy on R1 and R3 to set as-path prepend on prefixes advertised to AS5 and AS67. 

R1:

!
route-map LAST permit 100
 set as-path prepend 12 12 12 12 12
router bgp 12
 bgp log-neighbor-changes
 neighbor IBGP peer-group
 neighbor IBGP remote-as 12
 neighbor IBGP update-source Loopback0
 neighbor IBGP send-community
 neighbor 5.0.15.5 remote-as 5
 neighbor 5.0.15.5 route-map LAST out
 neighbor 12.0.2.2 peer-group IBGP
 neighbor 12.0.3.3 peer-group IBGP
 neighbor 12.0.4.4 peer-group IBGP

R2:

!
router bgp 12
 bgp log-neighbor-changes
 network 12.0.0.0 mask 255.255.0.0
 neighbor IBGP peer-group
 neighbor IBGP remote-as 12
 neighbor IBGP update-source Loopback0
 neighbor IBGP send-community
 neighbor 12.0.1.1 peer-group IBGP
 neighbor 12.0.3.3 peer-group IBGP
 neighbor 12.0.4.4 peer-group IBGP

R3:

!
route-policy BGP_ALL
  pass
end-policy
!
route-policy PRIMARY_IN
  if destination in AS8 then
    set local-preference 300
  else
    pass
  endif
end-policy
!
route-policy SECONDARY_IN
  if destination in AS8 then
    set local-preference 200
  else
    pass
  endif
end-policy
!
route-policy SECONDARY_OUT
  prepend as-path 12 3
end-policy
!
 address-family ipv4 unicast
 !
 neighbor-group IBGP
  remote-as 12
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
 neighbor 12.0.1.1
  use neighbor-group IBGP
 !
 neighbor 12.0.2.2
  use neighbor-group IBGP
 !
 neighbor 12.0.4.4
  use neighbor-group IBGP
 !
 neighbor 67.0.36.6
  remote-as 67
  address-family ipv4 unicast
   route-policy SECONDARY_IN in
   route-policy SECONDARY_OUT out
  !
 !
 neighbor 67.0.37.7
  remote-as 67
  address-family ipv4 unicast
   route-policy PRIMARY_IN in
   route-policy BGP_ALL out
  !
 !
!

R6:

!
route-map NO_TRANSIT permit 10
 match ip address prefix-list AS67
 set metric 10000
 set community no-export
route-map NO_TRANSIT permit 100
 set community no-export
router bgp 67
 bgp log-neighbor-changes
 network 67.0.0.0 mask 255.255.0.0
 neighbor 8.0.68.8 remote-as 8
 neighbor 67.0.36.3 remote-as 12
 neighbor 67.0.36.3 send-community
 neighbor 67.0.36.3 route-map NO_TRANSIT out
 neighbor 67.0.67.7 remote-as 67

R7:

Verification: