97 posts categorized "Chris Greer" Feed

How TCP Works - The Receive Window (by Chris Greer)

What does that Window field in the TCP header do? 

Many people ask this question after capturing a trace file with Wireshark. What is the TCP Window? How does it work? How can I use it to troubleshoot performance problems? 

We will answer these questions and more in this nine minute video. Check it out! 

Note: This video focuses on the TCP Receive window. We will cover the send window in another video. 

 

Author Profile - Chris Greer is a Network Analyst for Packet Pioneer LLC and a Certified Wireshark Network Analyst. Chris regularly assists companies in tracking down the source of network and application performance problems using a variety of protocol analysis and monitoring tools including Wireshark. Chris also delivers training and develops technical content for several analysis vendors. Got network problems? Let's get in touch

Chris Greer Packet Pioneer Logo



 


Intro to Wireshark – Sharkweek Teaser! (by Chris Greer)

Does opening a packet trace stress you out?

If so, you aren’t alone. Packet analysis is tedious, detailed, and can be very time consuming. Usually captures are taken to troubleshoot issues when the stakes are high and failure to find the problem is not an option. You may even have your boss breathing down your neck, expecting you to miraculously see the smoking gun in a matter of minutes, leaving you to wonder if your job is on the line.

Hey, we’ve all been there.

Packet analysis with Wireshark is an art form that can take a long time to develop. Gaining comfort with trace files starts with some basic steps that can go a long way in helping you find the culprit of your performance or security problem. Here, we will take a look at a couple quick hints that all new Wireshark users should know – but we will definitely leave some for the Intro to Wireshark session at Viavi Sharkweek starting on Monday, November 6th. Register here! https://observer.viavisolutions.com/wireshark-week/

Step 1.

Know the packet path and capture well.

Continue reading "Intro to Wireshark – Sharkweek Teaser! (by Chris Greer)" »


How TCP Works - Acknowledgment Numbers (by Chris Greer)

Let's learn more about TCP. 

So far, we've looked at the handshake process and how sequence numbers work. Now, let's check out how the acknowledgment process works with TCP. 

After all, this is a critical component of making TCP a connection-oriented, reliable transport protocol. Understanding how these numbers work goes a long way in troubleshooting issues in networks and applications. The better we understand these processes, the faster we can spot issues when things are broken. 

Got four minutes? Check it out! 

 

Thanks for checking it out and hopefully it helps all packet-heads out there! 

Continue reading "How TCP Works - Acknowledgment Numbers (by Chris Greer)" »


How TCP Works - Sequence Numbers (by Chris Greer)

TCP is important stuff for network engineers to know. 

Why? 

Today's problems aren't so cut-and-dry as they used to be. When a problem strikes, we can't just say "it's not the network" and go along with our day. A core understanding of TCP and how it carries and acknowledges data goes a long way in finding the root cause of performance problems today. 

One key aspect of TCP that is important to learn is the Sequence and Acknowledgement process. To put it simply, these numbers in the TCP headers indicate how much data has been sent and received. They allow each endpoint to determine if there was packet loss, what needs to be retransmitted, and help to determine how much data is in flight. 

For a six-minute crash-course on how TCP Sequence numbers work, check out this video:

 

Thanks for checking it out and hopefully it helps all packet-heads out there! 

Author Profile - Chris Greer is a Network Analyst for Packet Pioneer LLC and a Certified Wireshark Network Analyst. Chris regularly assists companies in tracking down the source of network and application performance problems using a variety of protocol analysis and monitoring tools including Wireshark. Chris also delivers training and develops technical content for several analysis vendors. Got network problems? Let's get in touch

Chris Greer Packet Pioneer Logo


How TCP Works - The Handshake (by Chris Greer)

This video uses Wireshark to show how the handshake process works in TCP. It is part of a new TCP Fundamentals series on the Packet Pioneer YouTube channel. I hope it helps the budding packet-heads out there! 

 Enjoy!

 

 

Author Profile - Chris Greer is a Network Analyst for Packet Pioneer LLC and a Certified Wireshark Network Analyst. Chris regularly assists companies in tracking down the source of network and application performance problems using a variety of protocol analysis and monitoring tools including Wireshark. Chris also delivers training and develops technical content for several analysis vendors. Got network problems? Let's get in touch

Chris Greer Packet Pioneer Logo




Sharkfest 2017 - Winning the Network Blame Game (by Chris Greer)

This session was recorded at Sharkfest 2017 on June 19th at Carnegie Mellon University. 

This session was recorded at Sharkfest 2017 – June 19th at Carnegie Mellon University in Pittsburgh. It delves into the reasons why people blame the network for performance problems, why these issues linger, and how network engineers can solve them using Wireshark.

I hope this helps you in resolving those pesky network and application issues.

Chris Greer Packet Pioneer Logo

Author Profile - Chris Greer is a Network Analyst for Packet Pioneer LLC and a Certified Wireshark Network Analyst. Chris regularly assists companies in tracking down the source of network and application performance problems using a variety of protocol analysis and monitoring tools including Wireshark. Chris also delivers training and develops technical content for several analysis vendors. Got network problems? Let's get in touch