Further reading
The following links are recommended for additional reading:
- TCP/IP overview: https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/linked/tcpip.htm
- Cisco 3 Tier architecture: https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Campus/campover.html
- Understanding network port numbers: https://hub.packtpub.com/understanding-network-port-numbers-tcp-udp-and-icmp-on-an-operating-system/