Use GNS3 with VIRL and Dynamips to add Serial interfaces to your VIRL topologies! Free software worth $200: https://goo.gl/613TUF
GNS3 switching options: https://youtu.be/zYaljXNfBdc
IOSv VIRL image import: https://youtu.be/dWxiLiXbLIc
Download images: https://youtu.be/_IgXj7wAiJU
Dynamips routers with GNS3: https://youtu.be/plgCr4Rbwz8
VIRL image downloads: https://virl.mediuscorp.com/my-account/
GNS3 Download: https://gns3.com/
GNS3 Support (Go here if you need help): https://gns3.com/community