ACK vs NAK approach


#1

Any ideas how to promote the acknowledgement of messages successfully received as opposed to requesting those missed. My students keep getting hung up on that. I am trying to build on using ACK as a more affirmative way to tell the sender you got the message. Also highlighting that if a NAK gets dropped sender doesn’t know, but if an ACK gets dropped and you add a timeout in your protocol for an ACK, the sender knows to resend and the receiver will then have an opportunity to resend the ACK.

Appreciate any ideas that add to my thoughts or how to better share with students.
Jim


#3

My students were also having a hard time understanding the need for the three-part TCP handshake.

In this analogy, Berkeley is my son’s name and I explain that in this non-fictional account he is located in the same room as me but is busy checking his Insta and Snapchats:

[Me] Berkeley. (SYN)

1 second passes

[Me] Berkeley. (SYN)

1 second passes

[Me] Berkeley. (SYN)

1 second passes

[Me] Berkeley. (SYN)

Another second passes

[Berkeley] What? (SYN/ACK)

Now I’m distracted putting something away, a second passes.

[Berkeley] What did you want Dad? (SYN/ACK)

[Me] I have three things I need you to do. (ACK)
[Me] One. Get off your phone.
[Me] Two. Clean your room.
[Me] Three. Walk the dogs.
[Me] In that order.
[Me] Did you get all of that?

[Berkeley] Clean my room. Walk the dogs.

[Me] But first get off your phone.

The kids instantly could relate to the analogy.


#4

Cool analogy. I’m trying to apply it to the issue brought up by @jreilly2016 regarding ACK vs NAK.

I had to just now look up what these terms mean as they’re new to me so hopefully I’m applying this correctly.

Proposed ACK solution Jim is encouraging:
[Me] I have three things I need you to do.
[Me] One. Get off your phone.
[Me] Two. Clean your room.
Berkeley gets distracted.
[Me] Three. Walk the dogs.
[Me] In that order.
[Me] What were those things again?

I get distracted.
[Berkeley] Get off my phone. Clean my room.

1 sec passes
[Me] Well?
[Berkeley] Get off my phone. Clean my room.
[Me] And walk the dog.

Student’s proposed solution of NAK that Jim is trying to discourage:
[Me] I have three things I need you to do.
[Me] One. Get off your phone.
[Me] Two. Clean your room.
Berkeley gets distracted.
[Me] Three. Walk the dogs.
[Me] In that order.
[Me] Did you miss any of that?

I get distracted.
[Berkeley] Sorry, you said there were three things. What was the third thing again?

[Me] Great, sounds like you didn’t miss anything. Bye.