Junos like open source routing software.

I simulate networks with Cisco and Juniper routers on my PC to study and understand very well about routing protocols. With GNS3 my life became simple in emulating Cisco routers. Running Juniper routers on Olive is kind tedious but one of my friends was gracious enough to prepare an Olive VM for me. But I wanted to run more routers with less trouble and I found that the following company offers a Junos like OS for free(offcourse without support). They do have some paid services which I do not need to care at this point. Please click on the following link to more about their product and download.

http://www.vyatta.com/

Emulating Cisco ASA firewall.

I have been trying to emulate Cisco ASA firewall various ways on my PCs. I used GNS3 and Qemu until I found this website recently. It is very easy now to emulate an ASA in VMWare using this ISO. Please try.

http://asa_project.gromnet.net

Container gardening.

I live in a single bed room rental apartment which has a small patio. Luckily I get lot of light in the patio. I got so crazy about container gardening. I did not setup a goal to grow vegetables to reduce my costs, but I wanted to entertain myself by taking care of the plants. I looked around internet for various ideas. I found the following link is very useful.

http://aggie-horticulture.tamu.edu/extension/container/container.html

Gardening is kind of mental relaxation for me. I feel realxed when I see plants growing. I feel relaxed when I take care of plants. I feel that I am achieving something when the plants grow and start giving flowers etc.

I will keep posting progress of my container garden.

Cheers.
Murthy

Time stamping the show commands.

If you want to time stamp the show commands along with current CPU utilization for a particular session, issue the following command.

 

terminal exec prompt timestamp

enable

 

Sample Output:

 

cs1#show run

Load for five secs: 0%/0%; one minute: 1%; five minutes: 1%

Time source is NTP, *11:00:00.713 Pacific Wed Feb 25 2009

 

Building configuration...

 

Current configuration : 30463 bytes

!

Cisco Hidden command for fabric utilizations.

show plat hard cap fabric

The output of the above command gives bus utlization etc. It is a very nice command

Identifying the backplane utilization on Catalyst 6500.

You always wanted to know the peak backplane utilization of Catalyst 6500 series switch and when it occurred.  You can find those details by typing this command. 

cs1 #show catalyst6000 traffic-meter 

  traffic meter =   0%  Never cleared

           peak =  51%        reached at 17:07:23 Pacific Thu Dec 20 2007

You can also setup SNMP monitoring and Syslog to alert you if the utilization crosses pre-defined values.  You can find more details on this at,

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094a96.shtml

Hope this command is useful to you.  If yes, please leave feedback.

Thank you.

Murthy

Fiber Optic Circulator Applications

• Add-Drop Multiplexing
• Fiber Sensors
• Bi-directional Pumping
• Bi-directional Signal Transmission Systems
• Coupling In-line Chromatic Dispersion Compensation Devices

Fiber optic circulators are non-reciprocating, one directional, three-port devices that are used in a wide range of optical setups and for numerous applications. An optical circulator is analogous to an electronic circulator and both perform similar functions. An optical circulator is a three-port device that allows light to travel in only one direction. A signal entered to Port 1 will exit Port 2, while a signal entering Port 2 will exit Port 3 all with minimal loss. Light entering port 2 experiences a large amount of loss at port 1, and light entering port 3 experiences a large amount of loss at ports 2 and 1.

Optical circulators are non-reciprocal optics. This means that any change in the properties of the light caused by passing through the device are not reversed by traveling in the opposite direction. Another example of non-reciprocal optics are Faraday rotators which are sometimes used in isolators. Because of its high isolation and low insertion loss, optical circulators are widely used in advanced communication systems as add-drop multiplexors, bi-directional pumping, and chromatic dispersion compensation devices. The example to the right depicts the use of a circulator to drop an optical channel from a DWDM system using a fiber bragg grating. The input DWDM channels are coupled into Port 1 of the device with a FBG device connected to Port 2. The single wavelength reflected off the FBG then reenters the circulator in port 2 and is routed accordingly to Port 3. The remaining signals pass through the FBG and exit on the top fiber.

Circlulators can also be used to send optical signal in two directions down a single fiber. A circulator is located at both ends of the fiber. Each circulator functions to add a signal in one direction while removing the signal in the other. See the example below.