Local Area Networks
IT 548
Telecommunications & Networking
Local Area Networks
Hood College Dept. of Computer Science Spring 2013
Layer 2: The Datalink Layer
•
•
2
Datalink layer provides a reliable communications link between devices. Breaks a data stream into chunks called frames, or cells.
Three key functions: • error detection • error correction • flow control
•
•
In LANs DL can be broken down into two sub-layers: • media access control (MAC) • logical link control (LLC). • flow and error control
Datalink Layer Addressing
3
• Frame transmitted
Datalink Layer Addressing
4
• Frame received • Note MAC addresses
LAN Architecture Model
• A network’s architecture consists of:
• Access methodology • Network Logical topology • Network Physical topology
5
No single architecture is best in all circumstances.
Access Methodology-CSMA/CD
1 4
6
2
5
3
6
Access Methodology-Token Passing
7
CSMA/CD vs. Token Passing
8
• CSMA/CD becomes less efficient at high bandwidth demand.
Network Topology
• Logical topology
• Sequential • Broadcast
9
• Physical topology
• Ring • Bus • Star
LAN Components
• • • • A central wiring concentrator Media Network Interface Cards Network interface card drivers.
10
A local area network, regardless of network architecture, requires the following components:
LAN Technology Architecture
11
NOS? What is that?
LAN Technology Choices & Implications
12
13
NIC Technology Analysis Grid
Ethernet
• Traditional Ethernet can be defined as follows:
• Access methodology: CSMA/CD • Logical topology: Broadcast • Physical Topology: Historically—bus, currently—star
14
Ethernet Frame Layout
15
• •
IEEE 802.3 is commonly referred to as “Ethernet”. There are differences as noted here.
LAN Architecture
16
• Typical Fast Ethernet Implementation
Gigabit Ethernet (aka 1000BaseX)
• An upgrade to Fast Ethernet,
Telecommunications & Networking
Local Area Networks
Hood College Dept. of Computer Science Spring 2013
Layer 2: The Datalink Layer
•
•
2
Datalink layer provides a reliable communications link between devices. Breaks a data stream into chunks called frames, or cells.
Three key functions: • error detection • error correction • flow control
•
•
In LANs DL can be broken down into two sub-layers: • media access control (MAC) • logical link control (LLC). • flow and error control
Datalink Layer Addressing
3
• Frame transmitted
Datalink Layer Addressing
4
• Frame received • Note MAC addresses
LAN Architecture Model
• A network’s architecture consists of:
• Access methodology • Network Logical topology • Network Physical topology
5
No single architecture is best in all circumstances.
Access Methodology-CSMA/CD
1 4
6
2
5
3
6
Access Methodology-Token Passing
7
CSMA/CD vs. Token Passing
8
• CSMA/CD becomes less efficient at high bandwidth demand.
Network Topology
• Logical topology
• Sequential • Broadcast
9
• Physical topology
• Ring • Bus • Star
LAN Components
• • • • A central wiring concentrator Media Network Interface Cards Network interface card drivers.
10
A local area network, regardless of network architecture, requires the following components:
LAN Technology Architecture
11
NOS? What is that?
LAN Technology Choices & Implications
12
13
NIC Technology Analysis Grid
Ethernet
• Traditional Ethernet can be defined as follows:
• Access methodology: CSMA/CD • Logical topology: Broadcast • Physical Topology: Historically—bus, currently—star
14
Ethernet Frame Layout
15
• •
IEEE 802.3 is commonly referred to as “Ethernet”. There are differences as noted here.
LAN Architecture
16
• Typical Fast Ethernet Implementation
Gigabit Ethernet (aka 1000BaseX)
• An upgrade to Fast Ethernet,