Issue with BGP

Ok guys, tell me I am not crazy.

I have setup a simple BGP lab, yet for some reason the transit router will not route traffic. I have attached my topology and configs as well as a few show commands. I am wondering if this IOS is buggy or if GNS3 is just messing with me.

I am not able to ping 172.16.0.1, 172.16.0.2 or 172.16.1.1 from R1, nor am I able to ping 10.0.0.1, 10.0.0.2 or 10.1.1.1 from R3. I can ping from R2 to everything sucessfully, but when I attempt to ping 172.16.1.1 from R2's 10.0.0.2 interface, the ping fails.

R1

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname ISP1
!
boot-start-marker
boot-end-marker
!
!
memory-size iomem 5
no aaa new-model
ip subnet-zero
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 10.1.1.1 255.255.255.0
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 bandwidth 128
 ip address 10.0.0.1 255.255.255.252
 clockrate 128000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
router bgp 200
 no synchronization
 bgp log-neighbor-changes
 network 10.1.1.0 mask 255.255.255.0
 neighbor 10.0.0.2 remote-as 100
 no auto-summary
!
ip classless
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname ITA
!
boot-start-marker
boot-end-marker
!
!
memory-size iomem 5
no aaa new-model
ip subnet-zero
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 192.168.0.1 255.255.255.0
!
interface Loopback1
 ip address 192.168.1.1 255.255.255.0
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 bandwidth 128
 ip address 10.0.0.2 255.255.255.252
 clockrate 128000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 bandwidth 128000
 ip address 172.16.0.2 255.255.255.252
 clockrate 128000
!
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 network 192.168.0.0
 network 192.168.1.0
 neighbor 10.0.0.1 remote-as 200
 neighbor 172.16.0.1 remote-as 300
 no auto-summary
!
ip classless
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname ISP2
!
boot-start-marker
boot-end-marker
!
!
memory-size iomem 5
no aaa new-model
ip subnet-zero
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 172.16.1.1 255.255.255.0
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 bandwidth 128
 ip address 172.16.0.1 255.255.255.252
 clockrate 128000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
router bgp 300
 no synchronization
 bgp log-neighbor-changes
 network 172.16.1.0 mask 255.255.255.0
 neighbor 172.16.0.2 remote-as 100
 no auto-summary
!
ip classless
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
 login
!
!
end

R1 "sh ip route"

Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 1 subnets
B       172.16.1.0 [20/0] via 10.0.0.2, 00:17:06
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.1.1.0/24 is directly connected, Loopback0
C       10.0.0.0/30 is directly connected, Serial0/0
B    192.168.0.0/24 [20/0] via 10.0.0.2, 00:17:06
B    192.168.1.0/24 [20/0] via 10.0.0.2, 00:17:06

R1 "sh ip bgp"

Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.1.0/24      0.0.0.0                  0         32768 i
*> 172.16.1.0/24    10.0.0.2                               0 100 300 i
*> 192.168.0.0      10.0.0.2                 0             0 100 i
*> 192.168.1.0      10.0.0.2                 0             0 100 i

R2 "sh ip route"

172.16.0.0/24 is subnetted, 2 subnets
C       172.16.0.0 is directly connected, Serial0/1
B       172.16.1.0 [20/0] via 172.16.0.1, 00:19:54
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
B       10.1.1.0/24 [20/0] via 10.0.0.1, 00:19:54
C       10.0.0.0/30 is directly connected, Serial0/0
C    192.168.0.0/24 is directly connected, Loopback0
C    192.168.1.0/24 is directly connected, Loopback1

R2 "sh ip bgp"

Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.1.0/24      10.0.0.1                 0             0 200 i
*> 172.16.1.0/24    172.16.0.1               0             0 300 i
*> 192.168.0.0      0.0.0.0                  0         32768 i
*> 192.168.1.0      0.0.0.0                  0         32768 i

R3 "sh ip route"

172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C       172.16.0.0/30 is directly connected, Serial0/0
C       172.16.1.0/24 is directly connected, Loopback0
     10.0.0.0/24 is subnetted, 1 subnets
B       10.1.1.0 [20/0] via 172.16.0.2, 00:20:59
B    192.168.0.0/24 [20/0] via 172.16.0.2, 00:20:59
B    192.168.1.0/24 [20/0] via 172.16.0.2, 00:20:59

R3 "sh ip bgp"

*> 10.1.1.0/24      172.16.0.2                             0 100 200 i
*> 172.16.1.0/24    0.0.0.0                  0         32768 i
*> 192.168.0.0      172.16.0.2               0             0 100 i
*> 192.168.1.0      172.16.0.2               0             0 100 i

BGP_Lab.jpg

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Comments

networker050184

The issue is the source of your pings. For example when R1 pings 172.16.0.1 its going to use a source of 10.0.0.1. R3 has no route back to this address and therefore drops the packet. Same thing with the other way. You can either advertise your blocks for your links, source the ping from one of the loopbacks or have a default to R2 to get it to succeed.

Monkerz

networker050184 wrote: »

The issue is the source of your pings. For example when R1 pings 172.16.0.1 its going to use a source of 10.0.0.1. R3 has no route back to this address and therefore drops the packet. Same thing with the other way. You can either advertise your blocks for your links, source the ping from one of the loopbacks or have a default to R2 to get it to succeed.

Yeah, I didn't expect the WAN interfaces to be pingable, but I thought the loopback interfaces on R1 and R3 would be.

networker050184

Well they will be pingable if you use a source address that the router has a route for, routing is a two way operation. Remember when you ping without specifying a source the router uses the outgoing interface address by default. Try "ping 172.16.0.1 source 10.1.1.1" or you might have to use the extended commands depending on your IOS.

Monkerz

networker050184 wrote: »

Well they will be pingable if you use a source address that the router has a route for, routing is a two way operation. Remember when you ping without specifying a source the router uses the outgoing interface address by default. Try "ping 172.16.0.1 source 10.1.1.1" or you might have to use the extended commands depending on your IOS.

Pinging from loopback to loopback is working. I need to keep studying

Sending 5, 100-byte ICMP Echos to 172.16.0.1, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
.....
Success rate is 0 percent (0/5)

Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/107/208 ms

networker050184

You just have to remember the basics. People get caught up with protocols and this and that when it really comes down to fundamental routing and router operations.

Monkerz

This is actually a lab out of the Route Lab Manual. I print out the labs and do them myself without following their directions to ensure I can complete the task. I believe the lab is wrong, it wants you to advertise the loopbacks on all three routers, the use a tcl script to ping all loopback interfaces. It says they should all ping successfully.

After I had failed to get it to work, I followed the lab word for word and came out with the same exact issue. I guess they didn't test their lab.

Thanks for the help.