TTL Security issue.

Guys

There is issue with using ttl-security feature in EBGP. When you advertise prefix , it will not show vaild route in BGP routing table even next hop or route source is accessible via IGP (EIGRP).

I have connected two router R2 and R5 on fast Ethernet , R2 isrunning AS 2 and R5 running AS 5.  The ttl-security feature is configured between R2 and R5 only.The R1is advertise 1.1.1.0/24 prefix to EBGP neighbour R2 and then R2 advertise to R5  which is also advertise via EIGRP (EIGRP is running on all interface). In additional R2 also advertise its connected interface2.2.2.0/24 however both route 1.1.1.0/24 and 2.2.2.0/24 is showing in BGP but not as valid and next hop for both advertise prefixes are inaccessible from R5

Topology   .

       R1---------------R2------------------------------------------------------------R5

R2 Config

R2#sh run | sec bgp

router bgp 2

 no synchronization

 bgplog-neighbor-changes

 network 2.2.2.0 mask255.255.255.0

 neighbor 5.5.1.1remote-as 5

 neighbor 5.5.1.1ttl-security hops 2

 neighbor 5.5.1.1update-source Loopback1

 no auto-summary

On R5 Config

R5#sh run | sec bgp

router bgp 5

 no synchronization

 bgplog-neighbor-changes

 neighbor 2.2.1.1remote-as 2

 neighbor 2.2.1.1ttl-security hops 2

 neighbor 2.2.1.1update-source Loopback1

 no auto-summary

R5#

R5#

R5#show ip bgp

BGP table version is 1, local router ID is 5.5.4.4

Status codes: s suppressed, d damped, h history, * valid,> best, i - internal,

              rRIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric LocPrf Weight Path

*  1.1.1.0/24       2.2.1.1                                0 2 1 i

*  2.2.2.0/24       2.2.1.1                  0             0 2 i

R5#

R5#show ip bgp 1.1.1.0/24

BGP routing table entry for 1.1.1.0/24, version 0

Paths: (1 available, no best path)

  Not advertised toany peer

  2 1

    2.2.1.1(inaccessible) from 2.2.1.1 (2.2.4.4)

      Origin IGP,localpref 100, valid, external

R5#

However 2.2.1.1 is reachable from R5 :

R5#ping 2.2.1.1

 

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 2.2.1.1, timeout is 2seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max =16/28/56 ms

R5#           

 

R5#show ip route 2.2.1.1
Routing entry for 2.2.1.0/24
  Known via "eigrp 100", distance 90, metric 409600, type internal
  Redistributing via eigrp 100
  Last update from 30.30.30.2 on FastEthernet0/0, 04:08:49 ago
  Routing Descriptor Blocks:
  * 30.30.30.2, from 30.30.30.2, 04:08:49 ago, via FastEthernet0/0
      Route metric is 409600, traffic share count is 1
      Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

R5#
R5#show ip route 1.1.1.0
Routing entry for 1.1.1.0/24
  Known via "eigrp 100", distance 90, metric 409600, type internal
  Redistributing via eigrp 100
  Last update from 50.50.50.1 on FastEthernet0/1, 04:08:55 ago
  Routing Descriptor Blocks:
  * 50.50.50.1, from 50.50.50.1, 04:08:55 ago, via FastEthernet0/1
      Route metric is 409600, traffic share count is 1
      Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

 

Please help.

 

Regards

Amit

 

 

Comments

  • Hi,

     If you know what ttl-security does, then this is 100% not related to it. Are you running dynamips? I remember seeing it somewhere else. Try using different IOS/hardware model. Or first maybe try a "clear ip bgp *" to trigger BGP process restart.

    Good luck with your studies

  • You don't need to run peering to loopbacks when using eBGP unless you are using multiple interfaces and want to achieve loadbalancing. Do you see anything out of the ordinary if you debug BGP events and debug ip routing?

    Is 1.1.1.0/24 reachable from R2?

  • Hello Cristian - yes I am running dynamips. This topic was discussed in new R&S COD.  I have trigger the BGP process but got same result.

    Hello Daniel -

    "You don't need to run peering to loopbacks when using eBGP unless you are using multiple interfaces and want to achieve loadbalancing"

    - I know , I am just doing testing with one interface only to understand how loopback peering work in EBGP with ttl-security.

    - Do you see anything out of the ordinary if you debug BGP events and debug ip routing?

    Need to check again on this.

    - Is 1.1.1.0/24 reachable from R2?

    Yes for sure , I am able to ping.


     

     

     

      

  • What happens if you announce another subnet at R1, create a loopback and announce it in BGP. Is that also inaccessible. Try running a debug of BGP while clearing the process. If you post full configs for R1, R2 and R5 I can run it in Dynamips and check for issues.

  • Yes I did some testing in my GNS, it's not related with ttl-security. Why you advertised your network 2.2.2.0 mask255.255.255.0 prefix on BGP? Because you are trying BGP peer with 2.2.2.2 as well.

    See here:

    R2#show ip route
    Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
           D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
           N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
           E1 - OSPF external type 1, E2 - OSPF external type 2
           i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
           ia - IS-IS inter area, * - candidate default, U - per-user static route
           o - ODR, P - periodic downloaded static route

    Gateway of last resort is not set

         200.200.200.0/32 is subnetted, 1 subnets
    C       200.200.200.200 is directly connected, Loopback200
         1.0.0.0/32 is subnetted, 1 subnets
    R       1.1.1.1 [120/1] via 12.12.12.1, 00:00:05, FastEthernet0/0
         2.0.0.0/32 is subnetted, 1 subnets
    C       2.2.2.2 is directly connected, Loopback0
         3.0.0.0/32 is subnetted, 1 subnets
    B       3.3.3.3 [20/0] via 3.3.3.3, 00:00:16 Issue should be with this because your BGP Session with this and next-hop as well
         23.0.0.0/24 is subnetted, 1 subnets
    C       23.23.23.0 is directly connected, FastEthernet1/0
         12.0.0.0/24 is subnetted, 1 subnets
    C       12.12.12.0 is directly connected, FastEthernet0/0
    R2#ping 3.3.3.3

    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
    .....

    R3#show running-config | section router bgp
    router bgp 3
     no synchronization
     bgp log-neighbor-changes
     network 3.3.3.3 mask 255.255.255.255
     neighbor 2.2.2.2 remote-as 2
     neighbor 2.2.2.2 ttl-security hops 2
     neighbor 2.2.2.2 update-source Loopback0
     no auto-summary
    R3#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    R3(config)#router bgp 3
    R3(config-router)#no network 3.3.3.3 mask 255.255.255.255
    R3(config-router)#^Z

    R2#show running-config | section router bgp
    router bgp 2
     no synchronization
     bgp log-neighbor-changes
     network 2.2.2.2 mask 255.255.255.255
     network 200.200.200.200 mask 255.255.255.255 I advertised this prefix
     neighbor 3.3.3.3 remote-as 3
     neighbor 3.3.3.3 ttl-security hops 2
     neighbor 3.3.3.3 update-source Loopback0
     no auto-summary
    R2#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    R2(config)#router bgp 2
    R2(config-router)#no network 2.2.2.2 mask 255.255.255.255
    R2(config-router)#do clear ip bgp * soft
    R2(config-router)#

    Now it's reachable

    R3#ping 200.200.200.200

    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 200.200.200.200, timeout is 2 seconds:
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 20/47/88 ms

    [:D]

  • hi nnn

    ok I have removed 2.2.1.0 network and advertise another prefix (82.82.82.0/24) on R2 and got same result. Please see below.

    R5#show ip bgp
    BGP table version is 1, local router ID is 5.5.4.4
    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
    *  1.1.1.0/24       2.2.1.1                                0 2 1 i
    *  82.82.82.0/24    2.2.1.1                  0             0 2 i
    R5#
    R5#show ip bgp 82.82.82.0
    BGP routing table entry for 82.82.82.0/24, version 0
    Paths: (1 available, no best path)
      Not advertised to any peer
      2
        2.2.1.1 (inaccessible) from 2.2.1.1 (2.2.4.4)
          Origin IGP, metric 0, localpref 100, valid, external
    R5#
    R5#ping 2.2.1.1

    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 2.2.1.1, timeout is 2 seconds:
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 8/26/56 ms

    R2 config

    router bgp 2
     no synchronization
     bgp log-neighbor-changes
     network 82.82.82.0 mask 255.255.255.0
      neighbor 5.5.1.1 ttl-security hops 2
     neighbor 5.5.1.1 update-source Loopback1
     no auto-summary

    R5 config

    R5#sh run | sec bgp
    router bgp 5
     no synchronization
     bgp log-neighbor-changes
     neighbor 2.2.1.1 remote-as 2
     neighbor 2.2.1.1 ttl-security hops 2
     neighbor 2.2.1.1 update-source Loopback1
     no auto-summary

     

     

  • Can you paste your routing table of R1/R2 and R5?

     

  • R2#show ip route
    Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
           D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
           N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
           E1 - OSPF external type 1, E2 - OSPF external type 2
           i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
           ia - IS-IS inter area, * - candidate default, U - per-user static route
           o - ODR, P - periodic downloaded static route

    Gateway of last resort is not set

         1.0.0.0/24 is subnetted, 4 subnets
    B       1.1.1.0 [20/0] via 172.168.123.1, 17:39:23
    D       1.1.2.0 [90/435200] via 30.30.30.5, 04:24:14, FastEthernet0/0
    D       1.1.3.0 [90/435200] via 30.30.30.5, 04:24:14, FastEthernet0/0
    D       1.1.4.0 [90/435200] via 30.30.30.5, 04:24:14, FastEthernet0/0
         50.0.0.0/24 is subnetted, 1 subnets
    D       50.50.50.0 [90/307200] via 30.30.30.5, 17:36:09, FastEthernet0/0
         2.0.0.0/24 is subnetted, 4 subnets
    C       2.2.1.0 is directly connected, Loopback1
    C       2.2.2.0 is directly connected, Loopback2
    C       2.2.3.0 is directly connected, Loopback3
    C       2.2.4.0 is directly connected, Loopback4
         155.10.0.0/24 is subnetted, 1 subnets
    D       155.10.10.0 [90/2195456] via 30.30.30.5, 04:24:16, FastEthernet0/0
         3.0.0.0/24 is subnetted, 4 subnets
    D       3.3.1.0 [90/156160] via 10.10.10.3, 04:24:22, FastEthernet2/0
    D       3.3.2.0 [90/156160] via 10.10.10.3, 04:24:22, FastEthernet2/0
    D       3.3.3.0 [90/156160] via 10.10.10.3, 04:24:22, FastEthernet2/0
    D       3.3.4.0 [90/156160] via 10.10.10.3, 04:24:22, FastEthernet2/0
         4.0.0.0/24 is subnetted, 4 subnets
    D       4.4.1.0 [90/2323456] via 30.30.30.5, 04:24:21, FastEthernet0/0
    D       4.4.2.0 [90/2323456] via 30.30.30.5, 04:24:21, FastEthernet0/0
    D       4.4.3.0 [90/2323456] via 30.30.30.5, 04:24:21, FastEthernet0/0
    D       4.4.4.0 [90/2323456] via 30.30.30.5, 04:24:21, FastEthernet0/0
         20.0.0.0/24 is subnetted, 1 subnets
    D       20.20.20.0 [90/284160] via 10.10.10.3, 17:36:11, FastEthernet2/0
         5.0.0.0/24 is subnetted, 4 subnets
    D       5.5.1.0 [90/409600] via 30.30.30.5, 04:24:17, FastEthernet0/0
    D       5.5.2.0 [90/409600] via 30.30.30.5, 04:24:18, FastEthernet0/0
    D       5.5.3.0 [90/409600] via 30.30.30.5, 04:24:18, FastEthernet0/0
    D       5.5.4.0 [90/409600] via 30.30.30.5, 04:24:18, FastEthernet0/0
         6.0.0.0/24 is subnetted, 4 subnets
    D       6.6.1.0 [90/412160] via 10.10.10.3, 04:24:18, FastEthernet2/0
    D       6.6.2.0 [90/412160] via 10.10.10.3, 04:24:18, FastEthernet2/0
    D       6.6.3.0 [90/412160] via 10.10.10.3, 04:24:18, FastEthernet2/0
    D       6.6.4.0 [90/412160] via 10.10.10.3, 04:24:18, FastEthernet2/0
         172.168.0.0/24 is subnetted, 1 subnets
    C       172.168.123.0 is directly connected, Serial0/0
    D    200.100.100.0/24 [90/2198016] via 10.10.10.3, 04:24:20, FastEthernet2/0
         82.0.0.0/24 is subnetted, 1 subnets
    C       82.82.82.0 is directly connected, Loopback55
         7.0.0.0/24 is subnetted, 4 subnets
    D       7.7.1.0 [90/2349056] via 30.30.30.5, 04:24:17, FastEthernet0/0
    D       7.7.2.0 [90/2349056] via 30.30.30.5, 04:24:19, FastEthernet0/0
    D       7.7.3.0 [90/2349056] via 30.30.30.5, 04:24:19, FastEthernet0/0
    D       7.7.4.0 [90/2349056] via 30.30.30.5, 04:24:19, FastEthernet0/0
    D    192.168.156.0/24 [90/2221056] via 30.30.30.5, 04:24:20, FastEthernet0/0
         40.0.0.0/24 is subnetted, 1 subnets
    D       40.40.40.0 [90/309760] via 10.10.10.3, 04:24:20, FastEthernet2/0
         10.0.0.0/24 is subnetted, 1 subnets
    C       10.10.10.0 is directly connected, FastEthernet2/0
         60.0.0.0/24 is subnetted, 1 subnets
    D       60.60.60.0 [90/2221056] via 30.30.30.5, 04:24:24, FastEthernet0/0
         30.0.0.0/24 is subnetted, 1 subnets
    C       30.30.30.0 is directly connected, FastEthernet0/0
    R2#

     ---------------------------

    R5#show ip route
    Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
           D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
           N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
           E1 - OSPF external type 1, E2 - OSPF external type 2
           i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
           ia - IS-IS inter area, * - candidate default, U - per-user static route
           o - ODR, P - periodic downloaded static route

    Gateway of last resort is not set

         1.0.0.0/24 is subnetted, 4 subnets
    D       1.1.1.0 [90/409600] via 50.50.50.1, 04:25:52, FastEthernet0/1
    D       1.1.2.0 [90/409600] via 50.50.50.1, 04:25:51, FastEthernet0/1
    D       1.1.3.0 [90/409600] via 50.50.50.1, 04:25:51, FastEthernet0/1
    D       1.1.4.0 [90/409600] via 50.50.50.1, 04:25:51, FastEthernet0/1
         50.0.0.0/24 is subnetted, 1 subnets
    C       50.50.50.0 is directly connected, FastEthernet0/1
         2.0.0.0/24 is subnetted, 4 subnets
    D       2.2.1.0 [90/409600] via 30.30.30.2, 17:38:10, FastEthernet0/0
    D       2.2.2.0 [90/409600] via 30.30.30.2, 17:38:10, FastEthernet0/0
    D       2.2.3.0 [90/409600] via 30.30.30.2, 17:38:10, FastEthernet0/0
    D       2.2.4.0 [90/409600] via 30.30.30.2, 17:38:10, FastEthernet0/0
         155.10.0.0/24 is subnetted, 1 subnets
    C       155.10.10.0 is directly connected, Serial0/1
         3.0.0.0/24 is subnetted, 4 subnets
    D       3.3.1.0 [90/412160] via 30.30.30.2, 04:25:51, FastEthernet0/0
    D       3.3.2.0 [90/412160] via 30.30.30.2, 04:25:51, FastEthernet0/0
    D       3.3.3.0 [90/412160] via 30.30.30.2, 04:25:51, FastEthernet0/0
    D       3.3.4.0 [90/412160] via 30.30.30.2, 04:25:51, FastEthernet0/0
         4.0.0.0/24 is subnetted, 4 subnets
    D       4.4.1.0 [90/2297856] via 155.10.10.4, 04:25:54, Serial0/1
    D       4.4.2.0 [90/2297856] via 155.10.10.4, 04:25:54, Serial0/1
    D       4.4.3.0 [90/2297856] via 155.10.10.4, 04:25:54, Serial0/1
    D       4.4.4.0 [90/2297856] via 155.10.10.4, 04:25:54, Serial0/1
         20.0.0.0/24 is subnetted, 1 subnets
    D       20.20.20.0 [90/309760] via 30.30.30.2, 04:25:54, FastEthernet0/0
         5.0.0.0/24 is subnetted, 4 subnets
    C       5.5.1.0 is directly connected, Loopback1
    C       5.5.2.0 is directly connected, Loopback2
    C       5.5.3.0 is directly connected, Loopback3
    C       5.5.4.0 is directly connected, Loopback4
         6.0.0.0/24 is subnetted, 4 subnets
    D       6.6.1.0 [90/435200] via 50.50.50.1, 04:25:55, FastEthernet0/1
    D       6.6.2.0 [90/435200] via 50.50.50.1, 04:25:55, FastEthernet0/1
    D       6.6.3.0 [90/435200] via 50.50.50.1, 04:25:55, FastEthernet0/1
    D       6.6.4.0 [90/435200] via 50.50.50.1, 04:25:55, FastEthernet0/1
         172.168.0.0/24 is subnetted, 1 subnets
    D       172.168.123.0 [90/2195456] via 50.50.50.1, 04:25:55, FastEthernet0/1
                          [90/2195456] via 30.30.30.2, 04:25:55, FastEthernet0/0
    D    200.100.100.0/24 [90/2221056] via 50.50.50.1, 04:25:55, FastEthernet0/1
         82.0.0.0/24 is subnetted, 1 subnets
    D       82.82.82.0 [90/409600] via 30.30.30.2, 04:01:06, FastEthernet0/0
         7.0.0.0/24 is subnetted, 4 subnets
    D       7.7.1.0 [90/2323456] via 155.10.10.4, 04:25:50, Serial0/1
    D       7.7.2.0 [90/2323456] via 155.10.10.4, 04:25:54, Serial0/1
    D       7.7.3.0 [90/2323456] via 155.10.10.4, 04:25:54, Serial0/1
    D       7.7.4.0 [90/2323456] via 155.10.10.4, 04:25:54, Serial0/1
    D    192.168.156.0/24 [90/2195456] via 50.50.50.1, 04:25:55, FastEthernet0/1
         40.0.0.0/24 is subnetted, 1 subnets
    D       40.40.40.0 [90/307200] via 50.50.50.1, 04:25:57, FastEthernet0/1
         10.0.0.0/24 is subnetted, 1 subnets
    D       10.10.10.0 [90/284160] via 30.30.30.2, 17:38:13, FastEthernet0/0
         60.0.0.0/24 is subnetted, 1 subnets
    D       60.60.60.0 [90/2195456] via 155.10.10.4, 04:25:57, Serial0/1
         30.0.0.0/24 is subnetted, 1 subnets
    C       30.30.30.0 is directly connected, FastEthernet0/0
    R5# 

    -------------------------------------

    R1#show ip route
    Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
           D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
           N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
           E1 - OSPF external type 1, E2 - OSPF external type 2
           i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
           ia - IS-IS inter area, * - candidate default, U - per-user static route
           o - ODR, P - periodic downloaded static route

    Gateway of last resort is not set

         1.0.0.0/24 is subnetted, 4 subnets
    C       1.1.1.0 is directly connected, Loopback1
    C       1.1.2.0 is directly connected, Loopback2
    C       1.1.3.0 is directly connected, Loopback3
    C       1.1.4.0 is directly connected, Loopback4
         50.0.0.0/24 is subnetted, 1 subnets
    C       50.50.50.0 is directly connected, FastEthernet0/1
         2.0.0.0/24 is subnetted, 4 subnets
    D       2.2.1.0 [90/435200] via 50.50.50.5, 04:26:27, FastEthernet0/1
    D       2.2.2.0 [90/435200] via 50.50.50.5, 04:00:20, FastEthernet0/1
    D       2.2.3.0 [90/435200] via 50.50.50.5, 04:26:28, FastEthernet0/1
    D       2.2.4.0 [90/435200] via 50.50.50.5, 04:26:28, FastEthernet0/1
         155.10.0.0/24 is subnetted, 1 subnets
    D       155.10.10.0 [90/2195456] via 50.50.50.5, 04:26:29, FastEthernet0/1
         3.0.0.0/24 is subnetted, 4 subnets
    D       3.3.1.0 [90/435200] via 40.40.40.6, 04:26:30, FastEthernet0/0
    D       3.3.2.0 [90/435200] via 40.40.40.6, 04:26:30, FastEthernet0/0
    D       3.3.3.0 [90/435200] via 40.40.40.6, 04:26:30, FastEthernet0/0
    D       3.3.4.0 [90/435200] via 40.40.40.6, 04:26:30, FastEthernet0/0
         4.0.0.0/24 is subnetted, 4 subnets
    D       4.4.1.0 [90/2297856] via 192.168.156.4, 04:26:29, Serial1/0
    D       4.4.2.0 [90/2297856] via 192.168.156.4, 04:26:29, Serial1/0
    D       4.4.3.0 [90/2297856] via 192.168.156.4, 04:26:29, Serial1/0
    D       4.4.4.0 [90/2297856] via 192.168.156.4, 04:26:29, Serial1/0
         20.0.0.0/24 is subnetted, 1 subnets
    D       20.20.20.0 [90/307200] via 40.40.40.6, 04:26:30, FastEthernet0/0
         5.0.0.0/24 is subnetted, 4 subnets
    D       5.5.1.0 [90/409600] via 50.50.50.5, 04:26:29, FastEthernet0/1
    D       5.5.2.0 [90/409600] via 50.50.50.5, 04:26:29, FastEthernet0/1
    D       5.5.3.0 [90/409600] via 50.50.50.5, 04:26:31, FastEthernet0/1
    D       5.5.4.0 [90/409600] via 50.50.50.5, 04:26:31, FastEthernet0/1
         6.0.0.0/24 is subnetted, 4 subnets
    D       6.6.1.0 [90/409600] via 40.40.40.6, 04:26:35, FastEthernet0/0
    D       6.6.2.0 [90/409600] via 40.40.40.6, 04:26:35, FastEthernet0/0
    D       6.6.3.0 [90/409600] via 40.40.40.6, 04:26:35, FastEthernet0/0
    D       6.6.4.0 [90/409600] via 40.40.40.6, 04:26:35, FastEthernet0/0
         172.168.0.0/24 is subnetted, 1 subnets
    C       172.168.123.0 is directly connected, Serial0/0
    D    200.100.100.0/24 [90/2195456] via 40.40.40.6, 04:26:36, FastEthernet0/0
         82.0.0.0/24 is subnetted, 1 subnets
    B       82.82.82.0 [20/0] via 172.168.123.2, 04:01:07
         7.0.0.0/24 is subnetted, 4 subnets
    D       7.7.1.0 [90/2323456] via 192.168.156.4, 04:26:32, Serial1/0
    D       7.7.2.0 [90/2323456] via 192.168.156.4, 04:26:32, Serial1/0
    D       7.7.3.0 [90/2323456] via 192.168.156.4, 04:26:32, Serial1/0
    D       7.7.4.0 [90/2323456] via 192.168.156.4, 04:26:32, Serial1/0
    C    192.168.156.0/24 is directly connected, Serial1/0
         40.0.0.0/24 is subnetted, 1 subnets
    C       40.40.40.0 is directly connected, FastEthernet0/0
         10.0.0.0/24 is subnetted, 1 subnets
    D       10.10.10.0 [90/309760] via 50.50.50.5, 04:26:32, FastEthernet0/1
                       [90/309760] via 40.40.40.6, 04:26:32, FastEthernet0/0
         60.0.0.0/24 is subnetted, 1 subnets
    D       60.60.60.0 [90/2195456] via 192.168.156.4, 04:26:33, Serial1/0
         30.0.0.0/24 is subnetted, 1 subnets
    D       30.30.30.0 [90/307200] via 50.50.50.5, 04:26:34, FastEthernet0/1
    R1#

     

     

     

     

     

     

     

  • Try using 7200 routers with diff IOS image and if still not functional post here: "show ip bgp summary" " sho ip bgp" "show ip bgp x.x.x.x" "show ip route connected" " show ip route eigrp" "show ip route bgp".

    Good luck with your studies.

  • I think now you don't have any issue on your routing. Can you try with different IOS?

     

    [:D]

  • hmm.... Writing with one hand is not going to be fun...but let me give it a try [;)]

     

    It's most likely a GNS Bug not even IOS bug IMHO. I have practiced EIGRP allot during my CCIE journey on GNS and My personal expereince was too bad with GNS bugs specially when it comes to EIGRP. Below is my set of TTL Security config :

    http://deepakarora1984.blogspot.com/2010/04/configuring-ebgp-peerings-without-using.html

     

    If you still doubt about IOS, you can verify it with Cisco IOS Bug Toolkit :

     

    https://tools.cisco.com/Support/BugToolKit/authc/forms/CDClogin.fcc?TYPE=33619969&REALMOID=06-d3358e44-2073-1068-9936-83846dc9304d&GUID=&SMAUTHREASON=0&METHOD=GET&SMAGENTNAME=$SM$GDuJAbSsi7kExzQDRfPKUItt%2bPcjKOjTGlbtk%2fRp7BdNYLiP9lyOBjXBU5PAxIXD&TARGET=http%3A%2F%2Ftools.cisco.com%2FSupport%2FBugToolKit%2Faction.do%3FhdnAction%3DsearchBugs

     

    Though you may need partner login for this If I remember correctly.

     

    HTH...

    Deepak Arora

    http://deepakarora1984.blogspot.com

     

     

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