BGP Practice Lab
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