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In case of Unicycle calico is used as the kubernetes CNI thus pods routing information is exchanged via BGP between all controller and worker nodes.
Two architectural options exist to implement the route exchange for calico pods
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(2) Using the more traditional full iBGP mesh between all calico pods
Validation has been primarily performed using the external fabric router approach. However limited validation has also been performed using the internal iBGP calico mesh.
In this the first case the external fabric router need needs to eBGP peer with all calico pods. To do this dynamic BGP peering is defined in the fabric router to accept BGP connection requests from any BGP speaker with an IP address from the calico 'ksn' network.
The site specific input yaml files documented in the Unicycle Deployment section of the release 1 documentation contain examples from the validations lab deployments of the the BGP related information required to force the calico pods to peer using eBGP such as own ASN and the external ASN of the fabric BGP router.
The Akraino/Airship deployment process configures the Unicycle pod's BGP configuration of the calico nodes. Modification of the Unicycle site specific input file fields allows the user to implement either the first or second BGP architectural option and in case of the first option the values of the external eBGP peer and its ASN.