18 posts categorized "Back-to-Basics" Feed

LMTV LIVE | How to Create Scalable Visibility in your Data Center (with Chris Bihary of Garland Technology)



YouTube LIVE event start time: Wednesday, July 19, 2017, 9:30 AM PST


Garland170x200How do you scale your network infrastructure to support multiple monitoring tools - while ensuring 100% packet capture?

This is the problem we have been hearing in the last few years. Data centers (D1 & D2) and enterprise networks have many challenges and two of the big ones are providing the IT department anytime access to full-duplex traffic, while guaranteeing full packet capture. Now layer on top of that a stack of 1G legacy monitoring tools in addition to the migration to 10G/40G and 100G speeds.

Join us for to learn about the latest visibility solution from Garland Technology’s as they introduce and demonstrate their Passive Fiber Modular Chassis System, a flexible, scalable and affordable high density solution for managing up to 24 links in a 1U box at network speeds of 1G/10G/40G/100G.


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Network Troubleshooting Tip - Understand the System (by Paul Offord)

When we get to the point in an investigation where we are about to break out Wireshark, the complexity of the packet analysis can seem quite daunting. And yet by covering a few key points can dramatically cut the time needed to analyze any diagnostic data.

In my previous post I covered the selection of a single symptom for investigation. In this blog we'll discover the need to understand more than just the network connectivity.

I remember visiting a third party data center and chatting to a network engineer who had been leading the investigation into a Citrix performance problem. He had spent months looking at this issue and I was shocked to discover how little he understood about the system he was analyzing. I asked him to draw a rough diagram showing the main components of the system and how they talked to each other. He couldn't and didn't see the need. As far as he was concerned, packets went into one switch port and they came out of another. "I don't need to know what connected to those ports", he informed me.

This may be an extreme example, but I have attended many meetings with teams that have been investigating a performance problem and nobody is able to draw the system on a whiteboard.

Ipt_diag

Modern systems are very complex, and so we need to sketch out the system with enough detail to provide everyone with an understanding of how it works, but not so much that it's overwhelming.  Advance7 has found ...

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Network Troubleshooting Tip - Focus on a Single Symptom (by Paul Offord)

When we get to the point in an investigation where we are about to break out Wireshark, the complexity of the packet analysis can seem quite daunting. And yet by covering a few key points can dramatically cut the time needed to analyze any diagnostic data.

In my previous post I covered the need to thoroughly understand a symptom. In this blog we'll look at the dangers looking for a common cause for multiple symptoms.

Imagine you are faced with a situation where users are complaining about three issues:

  • Word documents should open in less than 5 seconds, but intermittently take more than 30 seconds.
  • Excel workbooks should save in less than 15 seconds, but intermittently take more than 60 seconds.
  • Opening an Outlook Inbox should take less than 20 seconds, but sometimes takes more than 3 minutes.

All problems are reported as having started at the same time, and there’s a widespread belief that they are being caused by a network issue. This is the point where alarm bells should start to ring.

  Symptoms1

 

Maybe some of the symptoms are down to the same root cause, but maybe they are not, and starting by assuming they are is likely to lead to a very frustrating time. The choice of a single symptom and ...

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Network Troubleshooting Tip - Understand the Problem (by Paul Offord)

When we get to the point in an investigation where we are about to break out Wireshark, the complexity of the packet analysis can seem quite daunting. And yet by covering a few key points can dramatically cut the time needed to analyze any diagnostic data.

Let's start with a seemingly obvious point; do you understand the problem? Sounds like a stupid question, but I am amazed by how much time an IT team will spend investigating a problem that they barely understand.

Take the example of the bank that had a tiger team of seven investigating a "network performance problem" for four months. Staff in an Indian processing center were complaining that they couldn't meet business targets because the system was slow. The same system was used by UK workers and it performed fine for them; so it must be a network problem right? I arranged for us to call a user at the processing center.

The lady at the center explained that during the latter stages of processing a loan application the system intermittently threw a script error, and so she needed to start the process again. This made the system slow to use!

What had the tiger team been doing for the last four months? Crawling all over the network, Citrix servers, application servers, databases, etc. 

Scenario 1 Scenario 2 Scenario 3
Start Word Open Windows Explorer Open an Inbox item
Choose File -> Open Navigate to the shared folder Double-click on an attached Word doc
Navigate to the shared folder Double-click on a Word doc Hang for 30 seconds
Double-click on a Word doc Hang for 30 seconds Document opens in Word
Hang for 30 seconds Document opens in Word  
Document opens in Word    

The situation is often a little more subtle.

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LMTV LIVE | Taps vs SPAN Ports (with Keith Bromley and Jonathan Petkevich of IXIA)



YouTube Live Event starts at 9:30AM PST, Wednesday, March 8, 2017


Yx_X0tC2This week we will be speaking with Keith Bromley and Jonathan Petkevich, Senior Manager of Solutions Marketing and Product Manager of IXIA, respectively.

When it comes to monitoring your network, data collection is an extremely important subject. You need to know the type and quality of your data. For instance, is it an exact copy of the network data or has your monitoring data been modified (time stamps, checksums, etc.). The source of the data is important as it effects troubleshooting activities and network security. Join us for a discussion of how to capture the right type of monitoring data and a comparison of Tap-based vs. SPAN-based data.

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