Simple eBGP & iBGP Peering by Rick Frey

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You own a small WISP (Wireless Heroes) in your home town. Until recently, you have been using a subnet of addresses ( provided to you by your only upstream provider (Level 3). Those addresses were routed to you. Now you would like to take advantage of BGP so that you can use two Internet providers and advertise those addresses out both providers. Since you are going to be implementing BGP, you also want to build in a simple fail-over mechanism so that your customers will not be affected by outages with either provider. This is an uninfluenced BGP lab with no assumptions made about which route might be more appropriate for any particular traffic.


You have successful completed all of the hurdles to get two Internet providers and you are ready to peer with them. Step one will be to peer with Level 3. Step two will be to peer with Cogent. Step three will be to peer your three routers with each other. When you are finished, all five routers will be able to ping the public IPs on any of the other routers. The subnet of will be advertised out both providers. This will be a Cisco to MikroTik eBGP peering to make the lab more realistic. No changes will have to be made to the Cisco router configs. The BGP peering between Cogent and Level 3 has been provided for you.

Simple eBGP iBGP Peering.png


Tested on ROS 6.11

Virtual Devices Needed:

3 VMs running ROS (required)

2 Vms running a Cisco 3700 series (required)

1 VM running your choice of OS for web or Winbox management (optional)

Video Solutions:




File:BGB Peer 1 Initial.txt

File:BGB Peer 2 Initial.txt

File:BGP 1 Initial.txt

File:BGP 2 Initial.txt

File:Gateway Router Initial.txt

File:BGB Peer 1 Final.txt

File:BGB Peer 2 Final.txt

File:BGP 1 Final.txt

File:BGP 2 Final.txt

File:Gateway Router Final.txt

Pros to this Approach:

IP addresses from either provider or from ARIN can be advertised out both Internet providers.

If either of the connections to either Internet provider fails, the other Internet provider will take over.

Cons to This Approach:

There are no preferences in this scenario. There are no controls in place for any of the BGP routes.

Additional Resources:

ROS Manual -

ROS Manual -

IP Architechs – 1-855-MikroTik