The Network Microscope

Terry Slattery
Principal Architect

I have an occasional need for a network microscope.  You know the situation — someone contacts you with the story that the network is slow.  My vision of a network microscope is something that allows me to see what’s happening on the link.  Doing show interface doesn’t cut it for me because it is one snapshot and it doesn’t tell me what applications and users are using the link.

What I want starts with a rapid snmp poller that plots the collected data in a strip-chart format over time, rather like MRTG, but with a fast polling frequency.  A header that shows the interface configuration settings like IP address, VLAN ID and name, duplex, and speed would be very valuable too.
The poller should be able to show both in and out traffic as well as in and out error types using a stacked plot.  The polling period needs to be adjustable, possibly down to one second intervals.  [Note: Pete Welcher told me that Cisco updates its counters at about a one second interval, so aliasing can occur if polling at one second intervals.]

As I said above, it needs to be a strip-chart type display so I can see historical information.  It would also be useful to see running statistics for the collected data, such as peak, average, 95th percentile, and standard deviation.  This display helps me answer the question “how much” about the link’s utilization and errors.
The next part of the network microscope would show netflow data, which gives me an idea of the type of traffic that is using the link and the systems that are sending and receiving the data.  This data answers the questions of what and who about a slow link.

Tie the two parts together and I would have a tool in which I can click on a traffic burst and see the appropriate netflow data displayed.

The utilization and errors tell me how much, and netflow tells me what applications and who is using them.  If you’re aware of a tool like this, particularly if it is not packaged with an expensive NMS, I’d like to hear about it.

I’m also interested in other diagnostic tools that you find or envision.



Re-posted with Permission 

NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under


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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.