Wednesday, 28 December 2016

CCNP ROUTE BGP ATTRIBUTES LOCAL PREFERENCE PART 3

YOUTUBE :  


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BGP ATTRIBUTES

—WELL KNOWN : EVERYONE SUPPORTS  (AS,NEXT-HOP,ORIGIN,LOCAL-PRF,ATOMIC AGGREGATOR)
—OPTIONAL :     IN THE UPDATE AGGREGATOR,MED
—DESCRETIONARY:
   A. TRANSITIVE  ( TRAVEL FROM ROUTE TO ROUTE)

   B.NON-TRANSITIVE

HOW BGP FIND BETS PATH: 

—0.Ignore routes with inaccessible next hop address
—1.Weight
—2.Local-pref
—3.Prefer locally originated routes
—4.Shorter AS path
—5.Lowest origin type: where the route come from (i>E>?)
—6.Low MED
—7.Prefer ebgp over ibgp

ONE LOOK AT THE DIAGRAM: 
Attribute         Direction Applied          Traffic Flow Affected
Weight                    Inbound                                      Outbound
Local-Preference    Inbound                                      Outbound
AS-Path                  Outbound                                    Inbound
MED                      Outbound                                     Inbound

Lab Scenario: 
Task 1:
6.6.6.1-4 will Prefer route from R6>R5>R3>R1 with local-pref
Task 2:
With help of MED R1 thinks that R4 is its Primary ISP
Task 3:
Perform the same task with as-prepend connected 





THE DETAILED CONFIGURATION:

!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
interface Loopback1
 ip address 1.1.1.1 255.255.255.255
!
interface Loopback2
 ip address 1.1.1.2 255.255.255.255
!
interface Loopback3
 ip address 1.1.1.3 255.255.255.255
!
interface Loopback4
 ip address 1.1.1.4 255.255.255.255
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.12.1 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.13.1 255.255.255.252
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 network 1.1.1.1 0.0.0.0 area 0
 network 1.1.1.2 0.0.0.0 area 0
 network 1.1.1.3 0.0.0.0 area 0
 network 1.1.1.4 0.0.0.0 area 0
 network 10.1.12.0 0.0.0.3 area 0
 network 10.1.13.0 0.0.0.3 area 0
!
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 neighbor 2.2.2.2 remote-as 100
 neighbor 2.2.2.2 update-source Loopback1
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback1
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
---------------------------------------------------------------------------------------
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
interface Loopback1
 ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
 ip address 10.1.23.1 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.12.2 255.255.255.0
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.24.1 255.255.255.252
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 network 2.2.2.2 0.0.0.0 area 0
 network 10.1.12.0 0.0.0.3 area 0
 network 10.1.23.0 0.0.0.3 area 0
!
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 neighbor 1.1.1.1 remote-as 100
 neighbor 1.1.1.1 update-source Loopback1
 neighbor 1.1.1.1 next-hop-self
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback1
 neighbor 10.1.24.2 remote-as 400
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
----------------------------------------------------------------------------
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
interface Loopback1
 ip address 3.3.3.3 255.255.255.255
!
interface FastEthernet0/0
 ip address 10.1.23.2 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.35.1 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.13.2 255.255.255.252
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 network 3.3.3.3 0.0.0.0 area 0
 network 10.1.13.0 0.0.0.3 area 0
 network 10.1.23.0 0.0.0.3 area 0
!
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 neighbor 1.1.1.1 remote-as 100
 neighbor 1.1.1.1 update-source Loopback1
 neighbor 1.1.1.1 next-hop-self
 neighbor 2.2.2.2 remote-as 100
 neighbor 2.2.2.2 update-source Loopback1
 neighbor 10.1.35.2 remote-as 500
 neighbor 10.1.35.2 route-map LOC_POL in
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ip access-list standard local_pref
 permit 6.6.6.6
 permit 6.6.6.4
 permit 6.6.6.5
 permit 6.6.6.2
 permit 6.6.6.3
 permit 6.6.6.1
!
!
route-map LOC_POL permit 10
 match ip address local_pref
 set local-preference 1000
!
route-map LOC_POL permit 1000
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
---------------------------------------------------------------------------------

!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
interface Loopback1
 ip address 4.4.4.4 255.255.255.255
!
interface FastEthernet0/0
 ip address 10.1.46.1 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/0
 no ip address
 shutdown
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.24.2 255.255.255.252
 clock rate 2000000
!
router bgp 400
 no synchronization
 bgp log-neighbor-changes
 neighbor 10.1.24.1 remote-as 100
 neighbor 10.1.46.2 remote-as 600
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
---------------------------------------------------------------------------
!
hostname R5
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
interface FastEthernet0/0
 ip address 10.1.56.1 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.35.2 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 no ip address
 shutdown
 clock rate 2000000
!
router bgp 500
 no synchronization
 bgp log-neighbor-changes
 neighbor 10.1.35.1 remote-as 100
 neighbor 10.1.56.2 remote-as 600
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
------------------------------------------------------------------
!
hostname R6
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback1
 ip address 6.6.6.1 255.255.255.255
!
interface Loopback2
 ip address 6.6.6.2 255.255.255.255
!
interface Loopback3
 ip address 6.6.6.3 255.255.255.255
!
interface Loopback4
 ip address 6.6.6.4 255.255.255.255
!
interface Loopback5
 ip address 6.6.6.5 255.255.255.255
!
interface Loopback6
 ip address 6.6.6.6 255.255.255.255
!
interface FastEthernet0/0
 ip address 10.1.56.2 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/0
 no ip address
 shutdown
 clock rate 2000000
!
interface FastEthernet0/1
 ip address 10.1.46.2 255.255.255.252
 duplex auto
 speed auto
!
interface Serial0/1
 no ip address
 shutdown
 clock rate 2000000
!
router bgp 600
 no synchronization
 bgp log-neighbor-changes
 network 6.6.6.1 mask 255.255.255.255
 network 6.6.6.2 mask 255.255.255.255
 network 6.6.6.3 mask 255.255.255.255
 network 6.6.6.4 mask 255.255.255.255
 network 6.6.6.5 mask 255.255.255.255
 network 6.6.6.6 mask 255.255.255.255
 neighbor 10.1.46.1 remote-as 400
 neighbor 10.1.56.1 remote-as 500
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end
-----------------------------------------------------------

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