BGP Allow-AS In Lab


Images used in lab: VIOS-ADVENTERPRISEK9-M), Version 15.9(3)M2

Topology Interfaces Only

Topology With IP Addressing

The last octet is the router number unless specified otherwise. Example: PE11's G0/0 is Access to the initial configs, EVE-NG lab file and solution is below.


A BGP router will drop the prefix if it sees its own AS number in the AS Path. This is the default eBGP loop prevention behavior. This can cause problems in certain scenarios where multiple offices peer to the service provider using the same AS number. In this lab you’ll see this problem and modify the default behavior by using the BGP Allow-AS in feature. 


Download Lab

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Initial Configs


Allow-AS in is very similar to AS Override. Key points to remember: "Allow-AS in" is done on the customer side. "AS Override" is done on the provider side.

Hope you enjoyed this lab. If you have questions or need any help at all please leave a comment below and I’ll get back to you. 


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