Tuesday, March 26, 2013

BGP - Troubleshooting Lab 2

Objective
  • R3 and R4 must have 5.5.5.5/32 and 6.6.6.6/32 in their BGP/routing table. 
Sounds simple..? Well how about you figure it out then :) .. Here is the topology. 
Restrictions
  • Static routes should not be added anywhere!! In other words, get BGP to work properly. 
You should be able to figure out the issues with the following show commands below.  

 R1#show ip bgp nei 1.1.1.2 advertised-routes  
 BGP table version is 3, local router ID is 6.6.6.6  
 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,  
        r RIB-failure, S Stale  
 Origin codes: i - IGP, e - EGP, ? - incomplete  
   Network     Next Hop      Metric LocPrf Weight Path  
 *> 5.5.5.5/32    0.0.0.0         0          32768 i  
 *> 6.6.6.6/32    0.0.0.0         0          32768 i  

 R2#show ip bgp  
 BGP table version is 3, local router ID is 3.3.3.2  
 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,  
        r RIB-failure, S Stale  
 Origin codes: i - IGP, e - EGP, ? - incomplete  
   Network     Next Hop      Metric LocPrf Weight Path  
 *> 5.5.5.5/32    1.1.1.1         0            0   1 i  
 *> 6.6.6.6/32    1.1.1.1         0            0   1 i  

 R2#show ip route  
    1.0.0.0/24 is subnetted, 1 subnets  
 C    1.1.1.0 is directly connected, FastEthernet1/0  
    2.0.0.0/24 is subnetted, 1 subnets  
 C    2.2.2.0 is directly connected, FastEthernet2/0  
    3.0.0.0/24 is subnetted, 1 subnets  
 C    3.3.3.0 is directly connected, FastEthernet1/1  
    5.0.0.0/32 is subnetted, 1 subnets  
 B    5.5.5.5 [20/0] via 1.1.1.1, 00:10:49  
    6.0.0.0/32 is subnetted, 1 subnets  
 B    6.6.6.6 [20/0] via 1.1.1.1, 00:10:49  

 R2#show run | sec bgp  
 router bgp 2  
  no synchronization  
  bgp log-neighbor-changes  
  neighbor 1.1.1.1 remote-as 1  
  neighbor 1.1.1.1 soft-reconfiguration inbound  
  neighbor 2.2.2.3 remote-as 2  
  neighbor 2.2.2.3 next-hop-self  
  neighbor 2.2.2.3 prefix-list adv-r3-out out  
  neighbor 3.3.3.4 remote-as 4  
  neighbor 3.3.3.4 prefix-list adv-r4-out out  
  no auto-summary  

 R2#show ip prefix-list  
 ip prefix-list adv-r3-out: 2 entries  
   seq 10 permit 5.5.5.5/32  
   seq 20 permit 6.6.6.6/32  
 ip prefix-list adv-r4-out: 2 entries  
   seq 10 permit 5.5.5.5/32  
   seq 20 permit 6.6.6.6/32  

 R2#show ip bgp 5.5.5.5  
 BGP routing table entry for 5.5.5.5/32, version 2  
 Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to any peer)  
  Not advertised to any peer  
  1, (received & used)  
   1.1.1.1 from 1.1.1.1 (6.6.6.6)  
    Origin IGP, metric 0, localpref 100, valid, external, best  
    Community: no-advertise  
 R2#show ip bgp 6.6.6.6  
 BGP routing table entry for 6.6.6.6/32, version 3  
 Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to EBGP peer)  
  Advertised to update-groups:  
     2  
  1, (received & used)  
   1.1.1.1 from 1.1.1.1 (6.6.6.6)  
    Origin IGP, metric 0, localpref 100, valid, external, best  
    Community: no-export  

 R3#show ip bgp  
 BGP table version is 2, local router ID is 2.2.2.3  
 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,  
        r RIB-failure, S Stale  
 Origin codes: i - IGP, e - EGP, ? - incomplete  
   Network     Next Hop      Metric LocPrf Weight Path  
 *>i6.6.6.6/32    2.2.2.2         0  100      0    1 i  

 R3#show run | sec bgp  
 router bgp 2  
  no synchronization  
  bgp log-neighbor-changes  
  neighbor 2.2.2.2 remote-as 2  
  no auto-summary  

 R3#show ip route 
    2.0.0.0/24 is subnetted, 1 subnets  
 C    2.2.2.0 is directly connected, FastEthernet1/0  
    6.0.0.0/32 is subnetted, 1 subnets  
 B    6.6.6.6 [200/0] via 2.2.2.2, 01:59:56  

 R4#show run | sec bgp  
 router bgp 4  
  no synchronization  
  bgp log-neighbor-changes  
  neighbor 3.3.3.2 remote-as 2 
  neighbor 3.3.3.2 distribute-list block-most-routes-allow-certain in 
  no auto-summary  

 R4#show ip bgp summary  
 BGP router identifier 3.3.3.4, local AS number 4  
 BGP table version is 1, main routing table version 1  
 Neighbor    V     AS MsgRcvd MsgSent  TblVer InQ OutQ Up/Down State/PfxRcd  
 3.3.3.2     4     2   124   124    1  0  0             02:03:05     0  

 ip access-list standard block-most-routes-allow-certain
  permit 5.5.5.5
  permit 6.6.6.6
  deny   5.5.5.0 0.0.0.255
  deny   6.6.6.0 0.0.0.255


R4#show ip route  
    3.0.0.0/24 is subnetted, 1 subnets  
 C    3.3.3.0 is directly connected, FastEthernet1/0  
  • Why is 5.5.5.5/32 NOT in R3's BGP/routing table? 
  • Why is 5.5.5.5/32 and 6.6.6.6/32 NOT in R4's BGP/routing table?
  • What would you do to get this resolved??

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