ITIS 107 - Chapter 4 - Notes

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Ethernet

Ethernet is a network technology standard that needs the same bus topology, standard frame type, and same network access method.

Ethernet sub-committee is 802.3 (Ethernet).

The engineers resolved these issues by using data frames that contain MAC addresses to identify computers on the network and by using a process called CSMA/CD (carrier sense multiple access, collision detection) to determine which machine should access the wire at any given time.

All frames have a preamble that sends a 7 byte message that warns the receiving NIC that a frame is coming.

CSMA/CD

Carrier Sense: Each NIC on the network examines the wire before sending a frame. If the

node detects traffic, it will pause a random amount of time and try again.

Multiple Access: All machines have equal access to the wire. Access to the wire is on a first-come, first-served basis.

Collision Detection: If two NICs transmit at the same time, a collision results. NICs may listen to detect a collision.

Switched Ethernet

Ethernet switches give every conversation the full bandwidth of the network.

Source Address Table (SAT)

A switch copies the source MAC addresses and builds a table of MAC addresses of each connected computer based on which port it is plugged into.

The switch also allows us to communicate through Full Duplex.

Spanning Tree Protocol (STP)

Eliminates the problem of accidental bridge loops (i.e., redundant connections in a network).

With STP enabled:

Loops are detected

Looped port's state is set to blocking

STP-enabled switches use a Bridge Protocol Data Unit (BPDU) frame.

Determines distance between them

Helps keep track of changes on the network.

Rapid Spanning Tree Protocol (RSTP), 802.1w replaced the original STP in 2001.

10BaseT

Speed: 10 Mbps.

Signal type: Baseband.

Distance: 100 meters between the hub and the node.

Node limit: No more than 1024 nodes per hub.

Topology Star-bus topology: physical star, logical bus.

Cable type: CAT 3 or better UTP cabling with RJ-45 connectors.

10BaseFL

Speed: 10 Mbps.

Signal type: Baseband.

Distance: 2000 meters between the hub and the node.

Node limit: No more than 1024 nodes per hub.

Topology Star-bus topology: physical star, logical bus.

Cable type: Multimode fiber-optic cabling with ST or SC connectors.

10BaseTX

Speed: 100 Mbps.

Signal type: Baseband.

Distance: 100 meters between the hub/switch and the node.

Node limit: No more than 1024 nodes per hub/switch .

Topology: Star-bus topology: physical star, logical bus.

Cable type: CAT 5 or better UTP or STP cabling with RJ-45 connectors.

100BaseFX

Speed: 100 Mbps.

Signal type: Baseband.

Distance: Two kilometers between the hub/switch and the node.

Node limit: No more than 1024 nodes per hub/switch.

Topology: Star-bus topology: physical star, logical bus.

Cable type: Multimode fiber-optic cabling with ST or SC connectors.

1000BaseSX

Cable type: Multimode fiber-optic cabling with ST or SC connectors.

Distance: 500 meters

Speed: 1000 Mbps.

1000BaseLX

Cable Type: Singlemode fiber-optic cabling.

Distance: 5 kilometers.

Speed: 1000 Mbps.

SFF Fiber Connectors

Small Form Factor (SFF)

10GBaseSR

Cabling Type: Multiemode fiber-optic.

Distance: 300 meters

10GBaseSR

Cabling Type: Multimode fiber-optic

Distance 300 meters

10BaseLR

Cabling Type: Singlemode fiber-optic

Distance: 10 Kilometer.

10GbBaseER:

Cabling Type: Singlemode fiber-optic

Distance: 40 kilometers

10GbBaseLW:

Cabling Type: Singlemode fiber-optic

Distance: 40 kilometers