Week 5
Data Link Sublayers
Logical Link Control (LLC)
Media Access Control (MAC)
This lower sub-layer defines the media access processes performed by the hardware.It provides data link layer addressing and access to various network technologies
This upper sub-layer communicates with the network layer. It places info in the frame that identifies which network layer protocol is being used for the frame.
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Common Physical WAN
Mesh
Point-to-point
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Physical LAN Topologies
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Bus
Extended Star
Ring
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Provides high availability, but requires that every end system be interconnected to every other system. Administrative and physical costs can be significant.
Frame Fields
Frame start & Stop indicator flags
Adressing
Type
Hub And Spoke
Control
A central site interconnects branch sites using point-to-point links.
Data
The simplest topology that consist of a permanent link between two endpoints
Star
Connected to central intermediate device
Connected to respective neighbor
Interconnected other star topologies
Used in legacy networks.
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Hexadecimal
48-bit binary value expressed as 12 hexadecimal digits (4 bits per hexadecimal digit).
Identifies the beginning and end off frame
used to represent Ethernet MAC addresses and IP Version 6 addresses.
Indicates source and destination nodes
Identifies Layer 3 protocol
Identifies special flow control services such as QoS
Hexadecimal is a base sixteen system using the numbers 0 to 9 and the letters A to F.
Contains frame payload (i.e packet header, segment header and the data
Convert the decimal or hexadecimal value to binary, and then to convert the binary value to either decimal or hexadecimal
easier to express a value as a single hexadecimal digit than as four binary bits.
usually represented in text by the value preceded by 0x (E.g., 0x73).
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Elements of a Converged Network
Automated attedant
Mobility
Voice Messaging
Call Control