Ethernet Technologies, Standards, and Topologies, Slides of Network and System Administration

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LAN TECHNOLOGIES

Technology Options

Ethernet

Fast Ethernet

Gigabit Ethernet

10 Gig Ethernet

WLAN

802.3 Ethernet

Carrier-sense multiple access with collision detection (CSMA/CD).

CS = carrier sense MA = multiple access CD = collision detection

Base Ethernet standard is 10 Mbps.

100Mbps, 1Gbps, 10Gbps standards came later

Ethernet CSMA/CD

CSMA/CD (carrier sense multiple access with

collision detection) media access protocol is used.

Data is transmitted in the form of packets. Sense channel prior to actual packet transmission. Transmit packet only if channel is sensed idle; else, defer the transmission until channel becomes idle. After packet transmission is started, the node monitors its own transmission to see if the packet has experienced a collision. If the packet is observed to be undergoing a collision, the transmission is aborted and the packet is retransmitted after a random interval of time using Binary Exponential Backoff algorithm.

Ethernet Frame Structure

Preamble:

7 bytes with pattern 10101010 followed by one byte with pattern 10101011 Used to synchronize receiver, sender clock rates

Addresses: 6 bytes, frame is received by all adapters on a LAN and dropped if address does not match

Length: 2 bytes, length of Data field

CRC: 4 bytes generated using CR-32, checked at receiver, if error is detected, the frame is simply dropped

Data Payload: Maximum 1500 bytes, minimum 46 bytes

If data is less than 46 bytes, pad with zeros to 46 bytes

Length Docsity.com

Ethernet

10 Base 5 (Thicknet) (Bus Topology)

10 Base 2 (Thinnet) (Bus Topology)

10 Base T (UTP) (Star/Tree Topology)

10 Base FL (Fiber) (Star/Tree Topology)

Ethernet STAR Topology

Hub

Ethernet

Physical Media :-

10 Base5 - Thick Co-axial Cable with Bus Topology 10 Base2 - Thin Co-axial Cable with Bus Topology 10 BaseT - UTP Cat 3/5 with Tree Topology 10 BaseFL - Multimode/Singlemode Fiber with Tree Topology

Maximum Segment Length

10 Base5 - 500 m with at most 4 repeaters (Use Bridge to extend the network) 10 Base2 - 185 m with at most 4 repeaters (Use Bridge to extend the network) 10 BaseT - 100 m with at most 4 hubs (Use Switch to extend the network)

Fast Ethernet

Provision for Auto-Negotiation of media speed: 10 Mbps or 100Mbps (popularly available for copper media only).

Maximum Segment Length

100 Base TX - 100 m 100 Base FX - 2 Km (Multimode Fiber) 100 Base FX - 20 km (Singlemode Fiber)

Gigabit Ethernet

1 Gbps bandwidth.

Uses same CSMA/CD media access protocol as in Ethernet and is backward compatible (10/100/ modules are available).

1000BaseT (UTP), 1000BaseSX (Multimode Fiber) and 1000BaseLX (Multimode/Singlemode Fiber) standards.

Maximum Segment Length

1000 Base T - 100m (Cat 5e/6) 1000 Base SX - 275 m (Multimode Fiber) 1000 Base LX - 512 m (Multimode Fiber) 1000 Base LX - 20 Km (Singlemode Fiber) 1000 Base LH - 80 Km (Singlemode Fiber)