BGP Backdoor

Written by Rene Molenaar on 28 July 2010. Posted in BGP

Scenario:

As a professional poker player you have won the WSOP (World Series of Poker) and now your financial problems are over you decide to start your own online poker room. The bluffing is over it's time to configure your own company network...you have setup your own AS (100) and are connected to a service provider who is using AS 300. You are connecting your network to another big online poker website to exchange network information but you are using EIGRP instead of BGP to connect AS 100 and 200...the problem you face is that traffic from your AS towards AS 200 is being sent towards AS300 and not using the direct link between router Diamonds and Spades.

Goal:

All IP addresses have been preconfigured for you.
All routers have a loopback interface:
Router Diamonds: L0: 1.1.1.1 /24
Router Spades: L0: 2.2.2.2 /24
Router Hearts: L0: 3.3.3.3 /24
Router Clubs: L0: 4.4.4.4 /24
Configure EBGP between AS 100 and AS 300.
Router Diamonds: Advertise the 1.1.1.0 /24 network in BGP.
Configure IBGP on router Hearts and Clubs.
Configure EBGP between AS 200 and AS 300.
Router Diamonds: advertise the 1.1.1.0 /24 network in BGP.
Router Spades: advertise the 2.2.2.0 /24 network in BGP.
Ensure you can ping 2.2.2.2 from router Diamonds.
Ensure you can ping 1.1.1.1 from router Spades.
If you have any connectivity problems fix them by using next-hop-self or advertising the appropriate networks in BGP. Do not advertise the 192.168.12.X /24 network in any way.
Configure EIGRP between router Diamonds and Spades:
Advertise the 192.168.12.0 /24 network.
Advertise the 1.1.1.0 /24 network.
Advertise the 2.2.2.0 /24 network.
Disable auto-summary
Ensure you have an EIGRP neighbor relationship between the 2 routers.
Do a traceroute from router Spades to 1.1.1.1, which path is it taking?
Use a BGP command to make sure that traffic from router Spades towards 1.1.1.1 is using the 192.168.12.X link and is not being sent through AS 300.
When the link between router Diamonds and Spades fails it should use AS 300 to reach the 1.1.1.0 /24 network.

IOS:

c3640-jk9s-mz.124-16.bin

Topology:

Video Solution:

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Related Articles: ICND1 Assesment Lab
RIP Beginner
EIGRP Beginner
OSPF Single Area
EIGRP Intermediate

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Comments (13)

luismg
2010-12-20 12:16:54

This .net file needs the .1 or .2 or .whatever last octet of the ip :-)

ReneMolenaar
2010-12-21 15:37:14

I need to fix the startup configs for this one...coming soon

kumar981
2011-01-12 23:02:40

Hi Rene,

You mentioned about fixing the startup configs for this lab? Is this lab ready to be used?

Thanks

ReneMolenaar
2011-01-19 21:37:08

I just fixed the startup-config, no need to configure IP addresses anymore......ready to rock!

have fun!

Rosler
2011-04-29 11:32:17

Never knew about bgp backdoor before. Nice tutorial. Thanks very much.

Kaage
2011-06-14 08:01:04

Hi, there is only final configs available. Where is startup lab files?

ReneMolenaar
2011-06-19 18:59:06

You are right, there was no startup config. Just added it.

tel1mjf1
2011-09-02 19:29:43

Rene
the configs are not working here!

tel1mjf1
2011-09-02 19:31:34

disregard i got it. i can see the config now

tushar
2011-11-05 23:33:22

HI Rene,

I need the .net file. this file isnt in the .zip folder. Thanks.

Nurul

ReneMolenaar
2011-11-07 11:59:44

Thanks Nurul, I just fixed it!

bambam82
2012-04-22 10:59:32

just tried your setup and i'm seeing the interfaces on router R1 (Diamonds) are switched. Fa1/0 has the 13 subnet while according to the picture (and the .net file) should be the 12 subnet.

Both the starting config as the final one.

ReneMolenaar
2012-04-23 12:43:06

Thanks you are right, I just fixed it.

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