How TCP Works - Window Scaling Graph

[@pedrojaviermunozgarcia3721]

Chris, I have gone through all your videos and I have nothing more to do than thank you. Great job, spotless and clear. You saved me a lot of time study time!!!

[@AcTheMace]

Thanks!! Saved my grade for this homework.

[@unknownnespile9118]

It's good to see you back.

[@ChrisGreer]

Thanks!

[@netskills]

That's awesome that you share the trace file! Keep it up!

[@ChrisGreer]

Thanks, will do! Stay tuned....

[@mohitkhanna83]

Very useful my friend. Simple. To the point. Informative. Crisp! Thanks for covering only a small module.

[@spencerwilson-softwaredeve6384]

Awesome video, my instructor wants to make network security as confusing as possible it seems, you make it sound simple and now I understand what's going on. Thanks.

[@ChrisGreer]

Glad it helped you Spencer. Hey - check out my new course around cybersecurity with wireshark too! bit.ly/wiresharkhunt

[@miguelzambrano2389]

Many thanks for these video Chris they are amazing!! I usually learn way better with videos than reading books many thanks for this content!

[@ChrisGreer]

You are welcome. Thanks for the comment!

[@brahmadude8955]

My TCP Guru

[@ChrisGreer]

Thanks sir! Glad you liked it. I'll keep them coming!

[@vikrantd9675]

Many thanks for ur video.. really amazing..is there any video to troubleshoot intermediate application issue in wireshark....

[@cabsandy]

Cracking short video Chris-and liking the new background and mic set-up. Looks like a nice desk as well! :-)

[@ChrisGreer]

Thanks for the comment! Just set up the new studio and getting ready for much more content. Stay tuned.

[@lingfish1]

Awesome stuff mate. Discovered you today; amongst all the noise and crap out there, you explain things well, even for this seasoned network guy ;)

[@ChrisGreer]

Thanks and welcome!

[@nerfherder2915]

great vid! keep pounding us with tcp/ networking info.. it will stick, eventually!.. solid Volcom shirt too!

[@ChrisGreer]

:-) Thanks nerf! I will keep it up

[@remoscott1]

Thank you again, Chris! Keep up the great work.

[@ChrisGreer]

Thanks, will do!

[@mattchiles771]

Great set of vids and very usefull.

[@ChrisGreer]

Thanks for the comment Matt. Keep on capturing!

[@juanparra386]

Excelent video Chris. Thank you for your great explanation.

[@ChrisGreer]

My pleasure! Happy to help Juan

[@zelllers]

riverbed should just hire you honestly

[@smilefaxxe2557]

Thank you so much!!! This helped me a lot! ❤

[@shijianmin6159]

Very helpful, thanks!

[@ChrisGreer]

Glad it was helpful!

[@DeepakKumar-io1bu]

Great explanation

[@ChrisGreer]

Thanks Deepak!

[@VultUxTube]

Thank you for the videos! I try to follow what you explain, but the problem is what to do next? For example, a problem with retransmissions has been identified because the window size is small, how to fix it?

[@ChrisGreer]

Sure, glad you are enjoying them. You asked a very good question. What do we do with a low-window issue? Or retransmissions? Well, in the case of retransmissions, we need to track down where on the network we are seeing packet loss. This usually requires some more tools - like iPerf for example for measuring throughput. If we have a low window problem, then we can do some research into that exact issue - searching for the application in use and the device type. Usually we can come across recommendations from the developer or others who have tuned that system in a similar way. So it really just depends on what we find, but at least the packets helped us be confident about what to focus our troubleshooting on.

[@ManideepLadi]

Thank you for this information. I have one question will be able to get Number of RTTs from Wireshark?

[@ChrisGreer]

We can measure the RTTs and plot them on the Round Trip Graph but I don't see a specific number of plot points. Have to keep tinkering...

[@ManideepLadi]

@@ChrisGreer Thank you for your response. I think you should make a video on how different congestion control provider works like Cubic.

[@ManideepLadi]

One more question @Chris Greer. Can we approximate total time for request as multiplication of round trip time and number of rtts?

[@shirtguy9322]

Bro these vids are great 😍👌

[@ChrisGreer]

Glad you like them!

[@shirtguy9322]

@@ChrisGreer holy fuck Chris Greer replied to my comment

[@jarbystark]

And what means if bytes cross the green line ? i saw it a couple of times in my caps, could it happen if windows size cant be calculated precisely because there is no syn-synack-ack in capture?

[@gregnstuff1118]

Nice, can't wait to get a top zero window customer just to look at it in the 📊

[@PacketBomb]

Have I just ignored Bytes Out or is it relatively new? Very cool

[@ChrisGreer]

It's been there for a bit - I don't know exactly when it was added but I have noticed it for some time. It's awesome for getting an idea on the congestion window.

[@mattchiles771]

Looking forward on a series on WiFi maybe?

[@yohanmeier6061]

hi chris, the green line which represents the tcp window is that of host which receives the data? for example one displays the graph in the direction PC1 towards PC2, the data in flight are those of the PC1 and the window of reception of the pc2?

[@ChrisGreer]

You got it - the green line shows the receiver, the dark blue is the sender.

[@yohanmeier6061]

@@ChrisGreer thank you

[@gauravpatel8810]

Hi Chris, I have one question regarding tcp window. I have trace file in which sender and receiver not set window scale option in 3 way hand shake but eventually windows size increased in subsequent packets more then they set in first 3 packet. Can you please let me know what could be the reason.

[@ChrisGreer]

Hello Guarav, this is very common. Systems don't want to devote more resource to a connection unless they have to. So it is common to see them start out with a low window and then gradually increase it. It depends on the application and OS, but this behavior is very common to see.