By Bhavin Chauhan (09BCE005) Arpan Chavda (09BCE006)
What is Ethernet?
Most widely-installed local area network (LAN) technology
Uses coaxial cable or special grades of twisted pair wires
Uses CSMA/CD protocol & Manchester Encoding
Advance Ethernet is advance version of Ethernet which is called as Ethernet 2.0
Types of Advance Ethernet
10Base5 10BaseT 10baseFL 100BaseTX 100BaseFX Media Thick coax RG-8, RG-11 TIA/EIA UTP Cat 3,4,5,5e,6 (2 pair) 62.2/125 Multi-mode Fiber TIA/EIA UTP Cat 5 and up (2 pair) 62.2/125 Multi-mode Fiber Or Single mode fiber Speed 10 Mbps 10 Mbps 10 Mbps 100 Mbps 100 Mbps Max Seg. Length 500 Meters 100 Meters 2000 Meters 100 Meters 400/2000 Meters (full/half duplex), 10 Km
First Ethernet switch introduced by Networking Company ,Kalpana ,later acquired by Cisco.
Operates at layer 2 of OSI model
Switches forward and filter frames based on LAN addresses
It’s not a bus or a router (although simple forwarding tables are maintained)
Full duplex operation (send/receive frames simultaneously)
Connect two or more “segments” by copying data frames between them
Switches only copy data when needed
Higher link bandwidth
Own collision domain
Very less collision
Example of switched Ethernet
Store and forward switching. Stores the entire frame and performs a CRC check before forwarding. Best error correction, but takes the most time, impacting on speed.
Cut through switching. No error correction. Switch only reads address information. Provides best transmission speed, though on networks with a high number of frame errors this will end up slower than other methods.
Fragment free switching. Most frame corruption appears in the first 64 bytes of a frame. Fragment free checks only those bytes, discarding frames with errors. A good balance between error correction and speed.
Situation : Switch with
A1 On port1
BF On Port2
C9 On Port5
Switch forwarding table is initially empty.
A1 on Port 1 wants to send to C9 on port 5
Switch does not know port for c9
Broadcast the frame, acting as hub
Notes from source add. That A1 is on Port 1
Adds this info. To switch forwarding table.
C9 on Port 5 sends to A1 on Port 1
Table shows that A1 is on Port 1
Switch only sends out Port 1: Act like a switch !
Source add. Shows that C9 is on Port 5
Switch adds this info. To forwarding table
Every Few Minutes, Switch Erases switch forwarding table.
To eliminate obsolete info.
Relearning is very fast
Switches can be in hierarchy
Switches only learn that stations are out certain ports
“ 802.3u-1995 IEEE Standards for Local and Metropolitan Area Networks: Supplement to Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications Media Access Control (MAC) Parameters, Physical Layer, Medium Attachment Units, and Repeater for 100 Mb/s Operation, Type 100BASE-T”
In July 1993, a group of networking companies joined to form the Fast Ethernet Alliance.
The charter of the group was to draft the 802.3u 100BaseT specification of the IEEE and accelerate market acceptance of Fast Ethernet technology.
Approved in 1995
Other goals of the committee were: to maintain the Ethernet transmission protocol carrier sense multiple access collision detect (CSMA/CD); to support popular cabling schemes; and to ensure that Fast Ethernet technology will not require changes to the upper-layer protocols and software that run on LAN workstations.
Features of Fast Ethernet
Fast Ethernet supports a maximum data rate of 100 Mbps
Ability to coexist with existing network installations.
( These so-called "10/100" adapters can usually sense the speed of the line automatically and adjust accordingly.)
Based on CSMA/CD Media Access Control (MAC) protocol
Data can move from 10 Mbps to 100 Mbps without protocol translation or changes to application and networking software.
Fast Ethernet maintains CSMA/CD, the Ethernet transmission protocol. However, Fast Ethernet reduces the duration of time each bit is transmitted by a factor of 10, enabling the packet speed to increase tenfold from 10 Mbps to 100 Mbps.
( 5.12 microseconds instead of 51.2 microseconds)
Data can move between Ethernet and Fast Ethernet without requiring protocol translation, because Fast Ethernet also maintains the 10BaseT error control functions as well as the frame format and length.
The encoding used is 4B/5B with MLT-3 wave shaping plus FSR.
MLT-3 encoding (Multi-Level Transmit) is a line coding that uses three voltage levels
Table : Fast Ethernet Cabling and Distance Limitations
The MII layer of 100BaseT couples these physical sublayers to the CSMA/CD MAC layer
For the physical connection, the MII is implemented on Fast Ethernet devices such as routers, switches, hubs, and adapters, and on transceiver devices using a 40-pin
Designing with 100BaseT Ethernet Switch Ethernet Switch Server 100 Mbps links 10 Mbps links
Fast Ethernet Repeaters and Switches
Class I Repeater – supports unlike physical media segments (only one per collision domain)
Class II Repeater – limited to single physical media type (there may be two repeaters per collision domain)
Switches – to improve performance can add full-duplex and have autonegotiation for speed mismatches.
The 100BaseT specification describes a negotiation process that allows devices at each end of a network link to automatically exchange information about their capabilities and perform the configuration necessary to operate together at their maximum common level.
For example, autonegotiation can determine whether a 100-Mbps hub is connected to a 10-Mbps or 100-Mbps adapter and then adjust its mode of operation accordingly.
IEEE Std 802.3z- was formally approved by the IEEE Standards Board on June 25th, 1998.
“ IEEE Std 802.3z, extends the operating speed of the world's most popular local area network to 1 billion bits per second (1000 Mb/s) for interconnecting high-performance switches, routers, and servers in the backbone of local area networks. Maintaining backward compatibility with the over-100-million-node installed base of 10 Mb/s and 100 Mb/s was a key requirement”
(GMII) is an interface between the Media Access Control (MAC) device and the physical layer (PHY).
Provides speeds of 1000 Mbps for half-duplex and full-duplex operation.
Uses Ethernet frame format and MAC technology
CSMA/CD access method with support for one repeater per collision domain.
Backward compatible with 10 BASE-T and 100 BASE-T.
Uses 802.3 full-duplex Ethernet technology .
All Gigabit Ethernet configurations are point-to-point!
Figure 4-22. (a) A two-station Ethernet. (b) A multistation Ethernet.
Gigabit Ethernet Networks: Fast Ethernet
The challenges involved in accelerating to 1Gbps have been resolved by merging two technologies together: IEEE 802.3 Ethernet and ANSI X3T11 Fibre Channel.
Figure shows how key components from each technology have been leveraged to form Gigabit Ethernet.