Frame
- Header
- Frame Start
- Addressing
- Type
- Quality Control
- Packet (Data)
- Trailer
- FCS Frame Detection (CRC)
- Frame Stop
- Phan dau va cuoi khac bit nhau: 1010 va 1001
Data Link Layer
- LLC Logical Link Control
- Frames the Network layer packet
- Identifies the Network layer protocol
- Media Access Control
- Address the frame
- Masks the beginning and ending of the frame
Media Access Control Techniques
PPP: Point to point protocol (non shared media) //Khong can dieu khien truy cap duong truyen
Multi Access (shared media) //Dieu khien truy cap duong truyen
Phuong phap phan kenh:
- FDMA //Phan kenh theo tan so (Nhuoc diem: chi duoc di trong khoang da phan)
- TDMA //Phan kenh theo thoi gian (Moi tram chi duoc truyen trong 1 khe thoi gian nhat dinh – slot time)
- CDMA //Cho truyen toan bo giai tan va thoi gian, moi tram truyen dung 1 phuong phap ma hoa khac nhau
Phuong phap phan luot:
- Ring //Tao ra Token Card chay 1 vong tren 1 tram
- CSMA Random Access//dung cho Multi Access (van co truong hop xay ra dung do)
- CD: phat hien dung do (cho LAN co day)
- CA: phat hien dung do (cho LAN khong day)
Min Frame = 512 bit
JAM = 32bit
Back off sinh ra thoi gian Rand0m de truyen lai khi dung do
Media Access Control for Non-Shared Media:
- Simple-Duplex: Chi lam 1 chuc nang truyen hoac nhan
- Half-Duplex: Co the truyen va nhan nhung chi lam duoc 1 viec trong 1 thoi diem (Hub)
- Full-Duplex: Tai 1 thoi diem co the vua truyen va nhan (Switch)
Topology
- Logical //ban ve de chi ra cac phuong phap, cong nghe, kieu ket noi
- Point-to-point
- Multi-Access
- Ring
- Physical //ban ve ghi ro ket noi, loai nao, thiet bi nao
