OSI 7 Layer

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https://smallbiztrends.com/2013/09/osi-model-layer-networking.html

https://m.blog.naver.com/PostView.nhn?blogId=itperson&logNo=220390273478&proxyReferer=https%3A%2F%2Fwww.google.co.kr%2F


사진 출처 : https://www.google.co.kr/search?biw=1920&bih=974&tbm=isch&sa=1&ei=Un8VWs_hDYWx0gSEqaL4Bw&q=osi+7+layer+model+2%2C+3%2C+4&oq=osi+7+layer+model+2%2C+3%2C+4&gs_l=psy-ab.3...1318792.1332181.0.1332407.47.35.9.3.3.0.173.3170.28j5.34.0....0...1c.1j4.64.psy-ab..1.23.1774.0..0j0i30k1j0i5i30k1j0i8i30k1j0i24k1j0i19k1j0i8i30i19k1j0i30i19k1.81.xbGYEdfiRdA#imgrc=VCeWtWuWvjIWNM:

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https://muhammadtaufik7.wordpress.com/2015/08/09/whats-osi-layer/

Layer 1 : Physical
Physical layer is all about physic: cable, connector and bitrate thats all are included in physical layer. This layer just know about binner, 0 or 1. Physical layer process bit.
Layer 2 : Data Link
This is the second layer. Data link is process a frame and use MAC addressing. MAC address is unique identity for every device. If u have a laptop, maybe u will get minimal 2 MAC addresses, for ethernet card and wireless card. MAC Address contain hexadecimal number from 0-9 and A-F.
Layer 3 : Network
The third layer, its process packets and use ip addressing. IP address based on 32bit are divided to 4 octet and each octet had 8bit.
Layer 4 : Transport
This is fourth layer where TCP and UDP live there. TCP is reliable protocol means if packets was sent corrupt, it will be resend because TCP has error detection. TCP is used to download, ftp, http and etc. UDP is unreliable protocol and not have error detection. Packets still be sent even its corrupt. The benefit of UDP is faster than TCP. So… UDP is usually used to streaming and VOIP.


계층별 장비

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http://hahahoho5915.tistory.com/12