Spectrum's EVPN doesn't update the ASN connections in the topology

Document ID : KB000029167
Last Modified Date : 14/02/2018
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Description: How to update the BGP connections in topology when the exisiting port is connected to a new BGP peer link

 

Solution: 

When you have a BGP link terminated on the port models, you might have a requirement to update the existing link in topology when a customer terminates the old link in their environment. BGP local port connections in the topology are expected to connect to a new ASN cloud when a new link replaces the older link on the port models.

These links are expected to be updated during the scheduled EVPN discovery as this looks for the new BGP peer links on the port models during the discovery. Out of the box, Spectrum EVPN discovery doesn't update the new BGP peers when the port have an exisiting connection with a link, this is functioning as designed.

From the design, Spectrum never removes/replaces the connection to the ASN provider cloud if there is already an existing connection.  It seems the connection is locked with the CE router interface. The links doesn't update even with the manual EVPN discovery as Spectrum doesn't monitor for changes in Local or Remote ASN connected to the port models. These attributes are not polled and never updated by Spectrum.

The only solution is to manually delete the old link connected to the ASN cloud from the port models and connect the port to new ASN cloud. You can also trigger an EVPN discovery after removing the old ASN/BGP link from the respective port model to update the new connection with the current ASN cloud model.