Tuesday, March 19, 2013

BGP - Troubleshooting Lab

In this blogtorial, I will be posting configs of the routers and a few commands. Please leave me comments on what you think the issue maybe.

Consider this topology below. 
Objective: 
  • 11.11.11.11/32 should be pingable from R4. 
  • Static routes or artificial routes cannot be installed anywhere!! 
Hint -- There are three issues.

The entire config can be downloaded here so you can lab it up in GNS3.

 !  
 hostname R1  
 !  
 interface Loopback1  
  ip address 11.11.11.11 255.255.255.255  
  ip ospf network point-to-point  
 !  
 interface FastEthernet1/0  
  description connected to R2  
  ip address 1.1.1.1 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 router ospf 1  
  log-adjacency-changes  
  redistribute connected subnets route-map lo-2-ospf  
  network 1.1.1.1 0.0.0.0 area 0  
 !  
 ip prefix-list lo-2-ospf seq 10 permit 11.11.11.0/24  
 !  
 route-map lo-2-ospf permit 10  
  match ip address prefix-list lo-2-ospf  
 !  

 !  
 hostname R2  
 !  
 interface FastEthernet1/0  
  description connected to R1  
  ip address 1.1.1.2 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 interface FastEthernet1/1  
  description connected to R3  
  ip address 2.2.2.2 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 router ospf 1  
  log-adjacency-changes  
  network 1.1.1.0 0.0.0.255 area 0  
  default-information originate always  
 !  
 router bgp 2  
  no synchronization  
  bgp log-neighbor-changes  
  bgp soft-reconfig-backup  
  redistribute ospf 1 match internal external 2 route-map ospf-2-bgp  
  neighbor 2.2.2.3 remote-as 2  
  no auto-summary  
 !  
 ip prefix-list ospf-2-bgp seq 10 permit 11.11.11.11/32  
 !  
 route-map ospf-2-bgp permit 10  
  match ip address prefix-list ospf-2-bgp  
 !  

 !  
 hostname R3  
 !  
 interface FastEthernet1/0  
  description connected to r4  
  ip address 3.3.3.3 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 interface FastEthernet1/1  
  description connected to R2  
  ip address 2.2.2.3 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 router ospf 1  
  log-adjacency-changes  
  redistribute bgp 2 subnets route-map bgp-2-ospf  
  network 3.3.3.0 0.0.0.255 area 0  
 !  
 router bgp 2  
  no synchronization  
  bgp log-neighbor-changes  
  bgp soft-reconfig-backup  
  redistribute ospf 1  
  neighbor 2.2.2.2 remote-as 2  
  neighbor 2.2.2.2 soft-reconfiguration inbound  
  no auto-summary  
 !  
 ip prefix-list bgp-2-ospf seq 10 permit 11.11.11.11/32  
 !  
 route-map bgp-2-ospf permit 10  
  match ip address prefix-list bgp-2-ospf  
 !  

 !  
 hostname R4  
 !  
 interface FastEthernet1/0  
  description connected to r3  
  ip address 3.3.3.4 255.255.255.0  
  duplex auto  
  speed auto  
 !  
 router ospf 1  
  log-adjacency-changes  
  network 3.3.3.0 0.0.0.255 area 0  
 !  


'Show ip route' on R4 does not list 11.11.11.11/32 in its routing table.

Why doesn't R4 see the 11.11.11.11/32? Why can't R4 ping 11.11.11.11/32? How can you make it work? Leave comments :)