A bit off topic, but I found this interesting math trick, called Kaprekar's constant.
If you take four digits and perform a series of simple functions upon them, the end result is 6174.
rthurber's blog
A hack to split off PoE and Ethernet from a CAT5/6 cable
Submitted by rthurber on Mon, 11/28/2011 - 17:16A little hack to power a phone via one switch, while getting IP connectivity via another. This has limited practical application, but in my case I needed to connect a phone to a unique VLAN on a non-PoE switch. Plus, I just wanted to see if it would work.
Weather Services for Cisco IP Phone XML
Submitted by rthurber on Sun, 10/17/2010 - 22:14To get a Weather screeen via Cisco IP Phone Services, use our XML application on your Cisco phone. You will need your Unified Communications administrator to assist with adding our URL.
Paper, Rock, Scissors on a Cisco IP Phone
Submitted by rthurber on Mon, 02/15/2010 - 19:04We are always looking for unconventional uses of technology. The Cisco IP Phone XML API may not seem like the right platform for gaming. Unless that game is Paper, Rock, Scissors. Try it our here:
How to turn your Cisco IP Phone (7965) into a Digital Photo Display
Submitted by rthurber on Thu, 02/11/2010 - 13:25Cisco IP Phone XML applications and services provide a basic user interface for phone users.
End-to-End Performance Analysis
Submitted by rthurber on Fri, 01/15/2010 - 17:53When it comes to network based systems and applications, more often than not, your organization has run into performance or functional issues that are difficult to resolve. Precious operational cycles are lost as the problem is passed from one team to the next, each team doing their best to isolate components within their perspective silos. With today's multi-tier or distributed systems, a silo approach to problem resolution may not get to the root cause of all issues in a timely manner. This is where a skilled, end-to-end network analysis approach can pinpoint problem areas, providing quantitative, detailed data on performance and functional issues.
Here is just a sampling of the types of services PBM IT provides in this area of expertise:
- Application Network Troubleshooting – We specialize in troubleshooting performance or functional issues with distributed or client-server applications. Through packet analysis, fault isolation, data gathering and validation; we can assist in identifying the root cause of complex issues that plague enterprise applications.
- Application Network Analysis – We provide analysis focused on understanding and describing the properties of an application, as it pertains to the network. Data can be used to address an issue or to assist in understanding the impact of a change or anomaly within a system. For example:
- You need to understand why this application is performing poorly or why an application is failing.
- You need to make changes to your environment and want to understand the network aspects of the current systems in order to make the right choices for the effort as well as to identify potential risks or constraints to the effort.
Bandwidth Delay Product
Submitted by rthurber on Fri, 01/15/2010 - 17:46In a WAN environment, it is a common mistake to assume that a client's application throughput is directly related to WAN bandwidth - I have a DS3 (44Mbps) to my Data Center so I should be able to pull down a file at 44 Megabits per second. Most applications rely on TCP as an underlying transport mechanism, which is constrained by a window buffer. If your systems have a 65Kbyte window, only 65Kbytes of data can be in transit across the WAN before receiving an acknowledgment from the recipient host.
If your WAN DS3 latency is 100 millisecond, you could only have 65Kbytes of data in flight before the next acknowledgment. Another way to put this would be to say that you would only be able to achieve 81,250 bits per second! And we have not yet factored in contention from other users, or packet loss!!
