Category: Route

NOTE: THIS LAB IS NOT COMPLETE IT IS SETUP SO BGP GOES DOWN DUE TO AN ISSUE WITH KEEP ALIVES. EVERY 3 MINUTES BGP WILL GO DOWN AND THEN THE DYNAMIC ROUTING PROTOCOL WILL TAKE PLACE. AFTER THIS BGP WILL COME UP AGAIN FOR ANOTHER 3 MINUTES AND KEEP REPEATING. THIS IS AN EXAMPLE OF WHY YOU USE STATIC ROUTING ACROSS EXTERNAL PEERS. THERE ARE OTHER SOLUTIONS..FIND THEM!

• BGP’s primary purpose is to interconnect autonomous systems.
• Autonomous system (ASN) – Networks or a group of networks under the same administrations control and have a common routing policy.
• BGP is the glue that holds the internet together!
• BGP is designed to carry large amounts of routes.
• BGP removes the strain of carrying large amounts for IGPs.
• ISP speak ‘customer routes’
• External and Internal BGP use different policies.
• IBGP is not able to replace IGP’s. IBGP is meant to work alongside an IGP to create an efficient network.

External BGP

• External peers must be directly connected.
• TTL of 1 is given
• Time-to-live (TTL) tells a router whether or not the packet has been in the network too long and should be discarded – it times out at 0 and is discarded. Each hop is -1.
• This is to avoid long peering from occurring.
• TTL-Security is used to provide security to make sure neighbors are directly connected. This works by using a TTL of 255. This must be enabled on both peers (routers).

BGP Configuration Categories

• Configuration consists of two categories.
• Session commands tell BGP how to create the session.
• session commands can be global or per address family(Apply to all address families or just one)
• Policy commands control the routes.
• Policy commands are ALWAYS per address family.

Internal Peering

• No requirement for direct connectivity when doing iBGP.

Huh?

• After the configuration has been completed and we have verified R2 and R4’s loopbacks are being advertised to one another we check the BGP table and find something interesting.
• RIB-failure!!?? Normally failure is never a good thing but in this case we can see that we have an internal route that’s not being added to our routing table.
• We can check to see if their is a better route for our destination and we certainly see that the route is being learned VIA OSPF which has a lower admin distance than iBGP – thus winning the route.

vIOS1 Configuration

vIOS1#sh runn
 Building configuration…
 Current configuration : 3589 bytes
 !
 ! Last configuration change at 15:13:59 UTC Sat Mar 13 2021
 !
 version 15.6
 service timestamps debug datetime msec
 service timestamps log datetime msec
 no service password-encryption
 !
 hostname vIOS1
 !
 boot-start-marker
 boot-end-marker
 !
 !
 !
 no aaa new-model
 ethernet lmi ce
 !
 !
 !
 mmi polling-interval 60
 no mmi auto-configure
 no mmi pvc
 mmi snmp-timeout 180
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 ip cef
 no ipv6 cef
 !
 multilink bundle-name authenticated
 !
 !
 !
 !
 !
 redundancy
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 interface Loopback0
  ip address 192.168.0.1 255.255.255.255
  ip ospf 1 area 0
 !
 interface GigabitEthernet0/0
  ip address 192.168.69.1 255.255.255.0
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/1
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/2
  ip address 192.168.26.1 255.255.255.0
  ip ospf 1 area 0
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/3
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 !
 router eigrp 69
  network 192.168.0.0
  network 192.168.69.0
 !
 router ospf 1
 !
 router bgp 600
  bgp log-neighbor-changes
  neighbor 192.168.0.2 remote-as 900
  neighbor 192.168.0.2 ebgp-multihop 255
  neighbor 192.168.0.2 update-source Loopback0
  neighbor 192.168.0.4 remote-as 600
  neighbor 192.168.0.4 update-source Loopback0
  !
  address-family ipv4
   neighbor 192.168.0.2 activate
   neighbor 192.168.0.2 send-community
   neighbor 192.168.0.4 activate
   neighbor 192.168.0.4 send-community
  exit-address-family
 !
 ip forward-protocol nd
 !
 ip bgp-community new-format
 !
 no ip http server
 no ip http secure-server
 !

vIOS2 Configuration

vIOS2#sh runn
 Building configuration…
 Current configuration : 3368 bytes
 !
 ! Last configuration change at 15:19:15 UTC Sat Mar 13 2021
 !
 version 15.6
 service timestamps debug datetime msec
 service timestamps log datetime msec
 no service password-encryption
 !
 hostname vIOS2
 !
 boot-start-marker
 boot-end-marker
 !
 !
 !
 no aaa new-model
 ethernet lmi ce
 !
 !
 !
 mmi polling-interval 60
 no mmi auto-configure
 no mmi pvc
 mmi snmp-timeout 180
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 ip cef
 no ipv6 cef
 !
 multilink bundle-name authenticated
 !
 !
 !
 !
 !
 redundancy
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 interface Loopback0
  ip address 192.168.0.2 255.255.255.255
 !
 interface GigabitEthernet0/0
  ip address 192.168.69.2 255.255.255.0
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/1
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/2
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/3
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 !
 router eigrp 69
  network 192.168.0.0
  network 192.168.69.0
 !
 router bgp 900
  bgp log-neighbor-changes
  neighbor 192.168.0.1 remote-as 600
  neighbor 192.168.0.1 ebgp-multihop 255
  !
  address-family ipv4
   network 192.168.0.2 mask 255.255.255.255
   neighbor 192.168.0.1 activate
   neighbor 192.168.0.1 send-community
  exit-address-family
 !
 ip forward-protocol nd
 !
 ip bgp-community new-format
 !
 no ip http server
 no ip http secure-server

vIOS4 Configuration

vIOS4#sh runn
 Building configuration…
 Current configuration : 3363 bytes
 !
 ! Last configuration change at 15:18:58 UTC Sat Mar 13 2021
 !
 version 15.6
 service timestamps debug datetime msec
 service timestamps log datetime msec
 no service password-encryption
 !
 hostname vIOS4
 !
 boot-start-marker
 boot-end-marker
 !
 !
 !
 no aaa new-model
 ethernet lmi ce
 !
 !
 !
 mmi polling-interval 60
 no mmi auto-configure
 no mmi pvc
 mmi snmp-timeout 180
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 ip cef
 no ipv6 cef
 !
 multilink bundle-name authenticated
 !
 !
 !
 !
 !
 redundancy
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 !
 interface Loopback0
  ip address 192.168.0.4 255.255.255.255
  ip ospf 1 area 0
 !
 interface GigabitEthernet0/0
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/1
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/2
  ip address 192.168.26.2 255.255.255.0
  ip ospf 1 area 0
  duplex auto
  speed auto
  media-type rj45
 !
 interface GigabitEthernet0/3
  no ip address
  shutdown
  duplex auto
  speed auto
  media-type rj45
 !
 router ospf 1
 !
 router bgp 600
  bgp log-neighbor-changes
  neighbor 192.168.0.1 remote-as 600
  neighbor 192.168.0.1 update-source Loopback0
  !
  address-family ipv4
   network 192.168.0.4 mask 255.255.255.255
   neighbor 192.168.0.1 activate
   neighbor 192.168.0.1 send-community
  exit-address-family
 !
 ip forward-protocol nd
 !
 ip bgp-community new-format
 !
 no ip http server
 no ip http secure-server