Write a letter to Mr$.$ Winnicott.

Quickly explain the OSI model.

Explain what a firewall is to him and why he needs one, and where it fits in the OSI model.

Explain what a switch is$,$ and where it is on the OSI model as well.

Identify any equipment Sarah Russell $-$ his IT expert $-$ may have missed, especially security tools.

This letter is for an executive who is paying you, keep it professional, concise and informative.

Mr$.$ Winnicott is a smart man, if you do not provide sources for facts included in your letter, he may think you are making things up or using AI to write the letter.