I've updated the schema of my prototype address management database to reflect some additional relationships with VRFs and VLANs. Continue reading "One Unified Address Management, v1.3" »
Wednesday, June 27. 2007
Network Management Processes
In another exerpt from Cisco's book called Top-Down Network Design, Second Edition, there is a discussion regarding network mangement as being a part of network design. Very few companies, or many engineers for that matter, pay much attention to network management. Continue reading "Network Management Processes" »
Monday, June 25. 2007
Cisco Device Health
In Cisco's book, Top Down Network Design, one useful show command is 'show buffers'. Some useful SNMP statistics include:
- BusyPer. CPU busy percentage in the last 5-second period.
- AvgBusy1. 1-minute exponentially decayed moving average of the CPU busy percentage.
- AvgBusy5. 5-minute exponentially decayed moving average of the CPU busy percentage.
- LocIfInputQueueDrops. The number of packets dropped because the input queue was full.
- LocIfOutputQueueDrops. The number of packets dropped because the output queue was full.
- LocIfInIgnored. The number of input packets ignored by the interface.
- BufferElMiss. The number of buffer element misses. (You can also check misses for small, medium, big, large, and huge buffer pools.)
- BufferFail. The number of buffer allocation failures.
I've been doing most of my snmp statistics gathering on 5 minutes intervals. On some interfaces, it may be of value to step that up to 1 minute intervals. Of course, if my total collection time is over 1 minute, I may have problems with that.
From the same book, is this interesting statistic about why Window's file transfers over WAN links can go only 'so fast'. SMB acts like a ping-pong protocol. It can only send up to 32KB before requiring an acknowledgement. So if the delay is 50 ms end to end, and ignoring client and server delays, a client can receive at most 32 KB every 100 milliseconds, or 320 KB per second. This means that the maximum throughput is 2.56 Mbps, at best.
Sunday, June 24. 2007
Perl Tools
In an earlier article, I wrote about an IP Address Management database. To manage the data framework through the web, I'm thinking it might be well to use Catalyst Web Framework, a Perl based Model/View/Controller designed for data based web infrastructures. An Introductory Article introduces Catalyst use along with Ajax. Continue reading "Perl Tools" »
Cygwin Customizations
The default shell for Cygwin uses a DOS command shell, which has limited usefulness. To enhance the console experience, here are some customizations. To enhance the shell prompt, use the Cygwin installer to install 'rxvt'. Continue reading "Cygwin Customizations" »
TACACS + Linux
Up till now, I thought that TACACS use was limited to authentication/authorization of logins and commands on Cisco devices. There is an article at Freemode.net regarding TACACS + Linux for authentication.
Trading Site of the Day -- Blog on Blogs: The 24/7 Wall St. Twenty-Five Best Financial Blogs
A site called 24/7 Wall Street, which features "Insightful Analysis and Commentary for U.S. and Global Equity Investors", has an article called The 24/7 Wall St. Twenty-Five Best Financial Blogs. These are good starting off points for further research into the daily markets.
Debian Sample Network Configuration
For my future reference.
###################################################################### # /etc/network/interfaces -- configuration file for ifup(8), ifdown(8) # See the interfaces(5) manpage for information on what options are # available. ###################################################################### # We always want the loopback interface. # auto lo iface lo inet loopback # To use dhcp: # # auto eth0 # iface eth0 inet dhcp # An example static IP setup: (broadcast and gateway are optional) # # auto eth0 # iface eth0 inet static # address 192.168.0.42 # network 192.168.0.0 # netmask 255.255.255.0 # broadcast 192.168.0.255 # gateway 192.168.0.1
Linux Backup Application: Mondo
Mondo, Mindo. To be expounded on shortly.
Installing XWindows/KDE on Debian
For the initial installation of Debian, I simply do a 'standard' install. No desktop. I may also add database (which is PostgreSQL 8.1), dns, and web server (which is Apache 2.0). Continue reading "Installing XWindows/KDE on Debian" »
Debian Linux on a Mini-Box
I picked up a small form factor Mini-Box M200-LCD Barebone System. It is a nice small embedded systems unit with a backlit LCD and front panel buttons. I chose a unit with a 1GHz processor, 512MB of memory, and a 40GB harddrive. The unit does not have a floppy drive or a CDROM drive. It does come with ample USB slots. It also has a Compact Flash slot hidden behind a door on the front. Continue reading "Debian Linux on a Mini-Box" »
Saturday, June 23. 2007
Run Levels and Mode Switch Keys
Debian Admin has a some information regarding run levels (switching between single-user, console, and graphic modes). These are the basic run levels: Continue reading "Run Levels and Mode Switch Keys" »
Tuesday, June 12. 2007
Trading Site of the Day -- CASTrader Blog: A Quest for 50%-plus Returns
The complete byline for CASTrader Blog is "A quest for 50%-plus returns in the financial markets via Complex Adaptive Systems and Quantitative Finance.". Continue reading "Trading Site of the Day -- CASTrader Blog: A..." »
Sunday, June 10. 2007
Trading Site of the Day -- C++ Fast Delegates, plus Boost
No, C++ Fast Delegates aren't really trading algorithms, but they do help make trading algorithms fast. Continue reading "Trading Site of the Day -- C++ Fast Delegates,..." »
Saturday, June 9. 2007
Memory Leak Detection in Visual Studio 2005 C++ Applications
In some recent software development, when working with C++ in Visual Studio 2005, when ending a program which was run in the debugger, I'll sometimes get statements regarding memory leaks.
Each memory leak has a unique number associated with it. If these leaks and their numbers are repeatable, they can be tracked in Visual Studio by using the '_CrtSetBreakAlloc' call in your code.
In your code, near the beginning of execution, place the call, using the leak number as a parameter. This effectively creates a break point on the specific memory allocation call. When your code allocates the memory allocation, the break point will allow you to inspect the code and figure out why an appropriate dispose was not provided.