i have to transfer data to 300 meters using cat 6 cable any switching device for this application

Assuming that you don't need to worry much about bandwidth, you can simply place dumb switches along the route. As you probably know, CAT6 has a 100m maximum length, same as CAT5e.

Any particular reason for using CAT6? Besides support for 10Gb speed, it's pretty much identical to CAT5e.
 
The limit for any form of ethernet is 100m if you want to go farther you either need to put switches in ever 100m or you have to use something that is not ethernet.

If you can get power to the intermediate point switches are the simplest. Otherwise you need to use some form of ethernet converter devices. There are DSL things but maybe you get 100meg if you are lucky.
 

Kewlx25

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You can purchase a 1Gb Ethernet transmedia device and convert it to Fiber Ethernet. Then you can get distances measured in kilometers.

CAT6 is only 10Gb for very short distance, but it will support 5Gb at 100m. 2.5Gb will work on CAT5e at 100m