BGP: The Big Gory Protocol (Can you troubleshoot it?)

It isn't my fault, they configured it that way before I got here! That was the entry level technician's story Monday morning, and he was sticking to it.  :)

Here is the rest of the story.   Over the weekend, some testing had been done regarding a proposed BGP configuration.   The objective was simple, R1 and R3 needed to ping each others loobacks at 1.1.1.1 and 3.3.3.3 respectively, with those 2 networks, being carried by BGP.  R2 is performing NAT.    The topology diagram looks like this:

The ping between loopbacks didn't work, but R1 and R3 had these console messages:

R1#

%TCP-6-BADAUTH: No MD5 digest from 10.0.0.3(179) to 10.0.0.1(28556) (RST)

R1#

%TCP-6-BADAUTH: No MD5 digest from 10.0.0.3(179) to 10.0.0.1(28556) (RST)

R1#
R3#

%TCP-6-BADAUTH: No MD5 digest from 23.0.0.1(179) to 23.0.0.3(59922) (RST)

R3#

%TCP-6-BADAUTH: No MD5 digest from 23.0.0.1(179) to 23.0.0.3(59922) (RST)

R3#

The senior engineer looked at the configurations for R1, R2 and R3 and found 5 specific items, each of which was independently causing a failure.

Here is the challenge:  Can you find 1 or more of them?

Let us know what your troubleshooting skills can find, and post your comments here on the blog.

Here are the configurations for the 3 routers:

R1#show run

version 12.4

hostname R1

!

interface Loopback0

 ip address 1.1.1.1 255.255.255.0

!

interface FastEthernet0/0

 ip address 10.0.0.1 255.255.255.0

!

router ospf 1

 network 10.0.0.0 0.0.0.255 area 0

!

router bgp 1

 no synchronization

 bgp log-neighbor-changes

 network 1.1.1.1 mask 255.255.255.255

 neighbor 10.0.0.3 remote-as 3

 neighbor 10.0.0.3 password cisco

 no auto-summary

!

end

R1#
R2#show run

version 12.4

hostname R2

!

interface Loopback0

 ip address 2.2.2.2 255.255.255.0

!

interface FastEthernet0/0

 ip address 10.0.0.2 255.255.255.0

 ip nat inside

 ip virtual-reassembly

!

interface FastEthernet0/1

 ip address 23.0.0.2 255.255.255.0

 ip nat outside

 ip virtual-reassembly

!

router ospf 1

 network 2.2.2.2 0.0.0.0 area 0

 network 10.0.0.2 0.0.0.0 area 0

 network 23.0.0.2 0.0.0.0 area 0

!

ip nat inside source static 10.0.0.1 23.0.0.1

ip nat outside source static 23.0.0.3 10.0.0.3

!

end
R3#show run

version 12.4

hostname R3

!

interface Loopback0

 ip address 3.3.3.3 255.255.255.0

!

interface FastEthernet0/1

 ip address 23.0.0.3 255.255.255.0

!

router ospf 1

 log-adjacency-changes

 network 23.0.0.0 0.0.0.255 area 0

!

router bgp 3

 no synchronization

 bgp log-neighbor-changes

 network 3.3.3.3 mask 255.255.255.255

 neighbor 23.0.0.1 remote-as 1

 neighbor 23.0.0.1 password cisco123

 no auto-summary

!

end

R3#

Let us know what you find!

Best wishes.

UPDATE:   ANSWERS

Your contributions and input is great.  You ROCK!

I have summarized the 5 specific errors/issues with the configuration, and here they are:

• R2: NAT isn't fully baked. Can fix with  "ip nat outside source static 23.0.0.3 10.0.0.3 add-route" (or we could manually add the route as well).
• R1 & R3: The BGP passwords don't match, but it doesn't matter. BGP authentication doesn't work between NAT'd BGP neighbors, so it would have to be removed. :)
• R1 & R3: Incorrect network statements for loopback addresses on both BGP routers (incorrect mask)
• R1 & R3: Ebgp-multihop statements are needed on both neighbors (not directly connected EBGP)
• R2: R2 doesn't know how to reach 1.1.1.1 or 3.3.3.3 (non-BGP routing issue)

Again, thanks for the time and effort invested in this solution, and in learning in general.   I appreciate you!

Best wishes.