1. Data Link Layer - Ethernet Pertemuan 14 Matakuliah: H0484/Jaringan Komputer Tahun: 2007

2. Bina Nusantara Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menggunakan Ethernet

3. Bina Nusantara Outline Materi Standards Frame format

4. Bina Nusantara Frame Structure In synchronous transmission all transmissions are in frames Single frame format for all data and control exchanges Basic Structures: – Character Oriented Protocol (COP) - BSC (Bisynchronous) – Bit Oriented Protocol (BOP) - HDLC, SDLC

5. Bina Nusantara Generic Frame Structure (BOP)

6. Bina Nusantara Data Link Protocols HDLC - High-Level Data Link Control SDLC - Synchronous Data Link Control PPP - Point to Point Protocol Ethernet HDLC can be considered as the base protocol format

7. Bina Nusantara Ethernet Frame Format

8. Bina Nusantara Ethernet Frame The frame can be any number of bytes in length, depending on the specific technology used Ethernet frame can be as long as 1522 bytes.

9. Bina Nusantara Ethernet Layers

10. Bina Nusantara Logical Link Control Interface to higher levels Flow and error control Transmission of link level PDUs between two stations Must support multiaccess, shared medium Relieved of some link access details by MAC layer Addressing involves specifying source and destination LLC users – Referred to as service access points (SAP) – Typically higher level protocol

11. Bina Nusantara MAC Control Packet

12. Bina Nusantara MAC Frame Format MAC control Destination MAC address Source MAC address LLC – MAC layer receives data from LLC layer CRC – MAC layer detects errors and discards frames LLC optionally retransmits unsuccessful frames

13. Bina Nusantara Media Access Control Assembly of data into frame with address and error detection fields Disassembly of frame – Address recognition – Error detection Govern access to transmission medium – Not found in traditional layer 2 data link control For the same LLC, several MAC options may be available

14. Bina Nusantara Media Access Control (MAC) Shared-media broadcast technology. Ethernet’s MAC performs three functions:  Transmitting and receiving data packets  Decoding data packets and checking them for valid addresses before passing them to the upper layers of the OSI model  Detecting errors within data packets or on the network Specified by the technology being used. Dictates who can transmit and when (Only one station may transmit at a time; otherwise, their signals would be scrambled) Two types:  Deterministic (Token Ring)  Opportunistic (First come, first served - Ethernet)

15. Bina Nusantara Ethernet and IEEE 802.3 Specify similar technologies. Broadcast network. Using CSMA/CD algorithm. Hardware implementation. Differences: – Ethernet provides services corresponding to physical and datalink layer. – IEEE 802.3 specifies the physical layer and the channel-access portion of the data link layer but does not define a LLC protocol.

16. Bina Nusantara Protocol stack Link Control Protocol (LCP) Authentication Protocols Network Control Protocol (NCP) Bit Padding Digital Signals (DS) Services

17. Bina Nusantara Encapsulated LCP packet

18. Bina Nusantara An example