Ethernet - Networking presentation

ETHERNET
Presenter Viet Nguyen
Computer Networks Class – BIS2013
Professor Dr. Friedbert Kaspar – Vietnamese-German University

Ethernet – IEEE 802.3
• Introduction
– An overview of Ethernet
– Network topologies and Switched LAN
• Ethernet technology
– Ethernet technologies and cable types
– Ethernet frame
• Ethernet devices
– Link-layer switch
– Switches vs. Routers
• Ethernet applications
– Firewall
– IP Spoofing
• Summary
– Ethernet and its future
– References
Ethernet – Viet Nguyen
Prof. Dr. F. Kaspar – Computer Networking –
BIS2013 – Vietnamese-German University
Slide 2

INTRODUCTION
Slide 3

Overview
• Move Beyond Your LAN with Ethernet Services
• Ethernet is a family of computer networking technologies for local area
networks (LANs). Ethernet was commercially introduced in 1980 and
standardized in 1983 as IEEE 802.3.[1] Ethernet has largely replaced
competing wired LAN technologies such as token ring, FDDI, and ARCNET.
Slide 4

Overview (2)
• "Switching and 100Mbps speeds make 16Mbps technology obsolete" – the
time when Token Ring technology was replaced by Ethernet.
(http://www.techrepublic.com/blog/classics-rock/does-anyone-actually-
still-use-token-ring/)
Slide 5
1000BASE-T
http://www.sld.co.uk/products/comms/IPPBX_schematic.jpg
10BASE5

Network Topologies
Slide 6
http://upload.wikimedia.org/wikipedia/commons/9/96/NetworkTopologies.png

Network Topologies (2)
Slide 7
Star bus - Probably the
most common network
topology in use today, star
bus combines elements of
the star and bus topologies
to create a versatile
network environment.
Nodes in particular areas
are connected to hubs
(creating stars), and the
hubs are connected
together along the network
backbone (like a bus
network). Quite often, stars
are nested within stars
http://computer.howstuffworks.com/lan-switch2.htm

Switched Local Area Networks
Slide 8

TECHNOLOGY
Slide 9

Ethernet Technologies
Slide 10
Designation Supported Media Maximum
Segment Length
Transfer
Speed
Topology
100Base-TX Category5 UTP 100m 100Mbps Star,using either simple
repeater hubs or Ethernet
switches
100Base-FX Fiber-optic- two strands
of multimode 62.5/125
fiber
412m(Half-Duplex)
2000m(full-duplex)
100 Mbps
(200 Mb/s
full-duplex
mode)
Star(often only point-to-
point)
1000Base-SX Fiber-optic- two strands
fiber
260m 1Gbps Star, using buffered
distributor hub (or point-to-
point)
1000Base-LX Fiber-optic- two strands
fiber or monomode fiber
440m(multimode)
5000m(single-
mode)
1Gbps Star,using buffered distributor
hub (or point-to-point)
1000Base-CX Twinax,150-Ohm-
balanced, shielded,
specialty cable
25m 1Gbps Star(or point-to-point)
1000Base-T Category5 100m 1Gbps Star

Ethernet
Cable
Types
Slide 11
http://www.directron.
com/cableguide.html
http://academy.delmar.
edu/Courses/ITNW2313
/1Essentials.html

Ethernet Frame
• A data packet on an Ethernet link is called an Ethernet packet,
which transports an Ethernet frame as payload.
Slide 12
802.3 Ethernet packet and frame structure
Layer Preamble
Start of
frame
delimiter
MAC
destination
MAC source
802.1Q tag
(optional)
Ethertype (E
thernet II)
or length
(IEEE 802.3)
Payload
Frame
check
sequence(3
2-bit CRC)
Interpacket
gap
7 octets 1 octet 6 octets 6 octets (4 octets) 2 octets
46(42)[b]–
1500 octets
4 octets 12 octets
Layer 2
Ethernet
frame
← 64–1518(1522) octets →
Layer 1
Ethernet
packet
← 72–1526(1530) octets →
The internal structure of an Ethernet frame is specified in IEEE 802.3-2012
http://en.wikipedia.org/wiki/Ethernet_frame

Ethernet Frame (2)
• Ethernet II framing (The most common Ethernet Frame format, type II)
defines the two-octet EtherType field in an Ethernet frame that identifies
an upper layer protocol encapsulating the frame data. An EtherType value
of 0x0800 signals that the frame contains an IPv4 datagram. An EtherType
of 0x0806 indicates an ARP frame, 0x8100 indicates an IEEE 802.1Q frame
and 0x86DD indicates an IPv6 frame.
Slide 13
http://en.wikipedia.org/wiki/Ethernet_frame

IPDatagram
Encapsulation
Slide 14
http://www.tcpipguide.com/free/t_IPDatagramEncapsulation.htm

Sublayers of the data link layer
• Logical link control sublayer:
– Multiplexing protocols transmitted over the MAC layer (when
transmitting) and decoding them (when receiving).
– Providing node-to-node flow and error control
• Media access control (MAC) sublayer
– provides addressing and channel access control mechanisms
– The hardware that implements the MAC is referred to as
a medium access controller.
– The MAC layer emulates a full-duplex logical communication
channel in a multi-point network. This channel may
provide unicast, multicast or broadcast communication service.
Slide 15
http://en.wikipedia.org/wiki/Data_link_layer

Logical Link Control Services
• Ethernet
• Since bit errors are very rare in wired networks, Ethernet does not provide flow control
or automatic repeat request (ARQ),  incorrect packets are detected but only cancelled, not
retransmitted, retransmissions rely on higher layer protocols.
• As the EtherType in an Ethernet frame using Ethernet II framing is used to multiplex different
protocols on top of the Ethernet MAC header it can be seen as an LLC identifier. However,
Ethernet frames lacking an EtherType have no LLC identifier in the Ethernet header, and,
instead, use an IEEE 802.2 LLC header after the Ethernet header to provide the protocol
multiplexing function.
• Wireless LAN: In wireless communications, bit errors are very common. In wireless networks
such as IEEE 802.11, flow control and error management is part of the CSMA/CA MAC
protocol, and not part of the LLC layer. The LLC sub layer follows the IEEE 802.2 standard.
• HDLC (High-Level Data Link Control): Some non-IEEE 802 protocols can be thought of as
being split into MAC and LLC layers. For example, while HDLC specifies both MAC functions
(framing of packets) and LLC functions (protocol multiplexing, flow control, detection, and
error control through a retransmission of dropped packets when indicated), some protocols
such as Cisco HDLC can use HDLC-like packet framing and their own LLC protocol.
Slide 16
http://en.wikipedia.org/wiki/Logical_Link_Control

Media access control
Slide 17
http://en.wikipedia.org/wiki/Media_access_control
According to IEEE Std 802-2001 section 6.2.3 "MAC sublayer", the primary
functions performed by the MAC layer are:
•Frame delimiting and recognition
•Addressing of destination stations (both as individual stations and as groups of
stations)
•Conveyance of source-station addressing information
•Transparent data transfer of LLC PDUs, or of equivalent information in the Ethernet
sublayer
•Protection against errors, generally by means of generating and checking frame
check sequences
•Control of access to the physical transmission medium
In the case of Ethernet, according to 802.3-2002 section 4.1.4, the functions
required of a MAC are:
•receive/transmit normal frames
•half-duplex retransmission and backoff functions
•append/check FCS (frame check sequence)
•interframe gap enforcement
•discard malformed frames
•append(tx)/remove(rx) preamble, SFD (start frame delimiter), and padding
•half-duplex compatibility: append(tx)/remove(rx) MAC address

DEVICES
Slide 18

Link-Layer Switches
• A switch receives incoming link-layer frames, filters and
forwards them onto outgoing links. Switch filtering and
forwarding are done with a switch table.
• A switch has self-learning property (particularly for the
already-overworked network administrator) that its table is
built automatically, dynamically, and autonomously.
• Switches are plug-and-play devices and require no
intervention from a network administrator or user.
Slide 19

Switches vs. Routers
Slide 20
A router in that it forwards packets using MAC addresses (layer-
2) whereas a router is a layer-3 packet switch.

Switches vs. Routers (2)
Slide 21
Switches Routers
switches are plug-and-play not plug-and-play. their IP addresses need to be
configured
Switches can also have relatively high
filtering and forwarding rates since
switches have to process frames only up
through layer 2, whereas routers have to
process datagrams up through layer 3
larger per-packet processing time than switches, because
they have to process up through the layer-3 fields
routers do not have the spanning tree restriction, they
have allowed the Internet to be built with a rich topology
to prevent the cycling of broadcast
frames, the active topology of a switched
network is restricted to a spanning tree.
packets are not restricted to a spanning tree and can use
the best path between source and destination
No firewall integrated provide firewall protection against layer-2 broadcast
storms

Slide 22
Hub vs. Switch vs. Router
http://thamarai-stor.blogspot.com/2010/05/ikkks-switch-vs-router-vs-hub.html

Slide 23
http://www.cisco1900router.com/t
utorial-of-differences-between-hub-
bridge-switch-and-router.html
a bridge is a product that connects a local area network
(LAN) to another local area network that uses the same
protocol. Having a single incoming and outgoing port and
filters traffic on the LAN by looking at the MAC address,
bridge is more complex than hub. Bridge looks at the
destination of the packet before forwarding unlike a hub. It
restricts transmission on other LAN segment if destination
is not found.
A bridge works at the
data-link (physical
network) level of a
network, copying a
data frame from one
network to the next
network along the
communications path.

APPLICATIONS
Slide 24

Firewalls
Slide 25
http://www.vicomsoft.com/learning-center/firewalls/
Social engineering involves skills not unlike
those of a confidence trickster. People are
tricked into revealing sensitive information.
A firewall filters both inbound and outbound traffic.
"There are management solutions to
technical problems, but no technical
solutions to management problems"

Figure 9: Stateful Multilayer Inspection FirewallFigure 8: Application level Gateway
Figure 6: Packet Filtering Firewall Figure 7: Circuit level Gateway
Firewalls (2)
Slide 26

IP Spoofing
Slide 27
http://en.wikipedia.org/wiki/File:IP_spoofing_en.svg
Any router that
implements
ingress filtering
checks the
source IP field
of IP packets it
receives, and
drops packets if
the packets
don't have an IP
address in the
IP address block
that the
interface is
connected to

SUMMARY
Slide 28

The Ethernet Summary
• The Introduction covered the market use of
Ethernet and its related to the Network Layer.
• The Technology and Devices sections dive
deeper to the software and supported
hardware for the Ethernet: Ethernet Frame,
cable types, routers and switches.
• The Application gave an example of a real
world use from Ethernet knowledge.
Slide 29

Ethernet and its future
Slide 30
Report from The Future of Ethernet – Technology Exploration Forum on October 15, 2013 - October 16, 2013 at
Santa Clara, CA – Interconnectedness and the Future of Ethernet
http://www.enterprisenetworkingplanet.com/netsp/interconnectedness-and-the-future-of-ethernet-1.html
http://www.enterprisenetworkingplanet.com/netsp/interconnectedness-and-the-future-of-ethernet-2.html

Ethernet and its future (2)
• Vehicular Ethernet, the Internet of Things, and the Industry as an Ecosystem
– From enhanced traffic management and traffic alerts drawn from live video feeds
broadcast from individual vehicles to the ability to tax cars based on their miles driven, the
possible applications are endless.
• Standardizing software defined networking for interoperability
– "In the past, people have talked about SDN more on an individual basis. But the Ethernet
Alliance is supporting 802 in the standardization effort, which means we really want to be
able to take Vendor A, plug it into Vendor B, plug that into Vendor C, and have it all work,"
• Energy Efficient Ethernet
– As networks grow and evolve, their power consumption may rise, creating additional cost
issues. The Energy Efficient Ethernet (EEE) standard for twisted pair and backplane
Ethernet aims to counter that by reducing power consumption as activity drops.
• Interconnectedness and the importance of consensus-building
– Addressing both the main themes D'Ambrosia mentioned—interoperability and cost
concerns—will require a general consensus and interconnectedness among diverse
segments of the networking community. Other TEF 2013 panels bear this out, from the
panel session that pulled leaders from 802.1, 802.3, and 802.11 up onto a stage with the
chair of 802, to sessions that focused on the synergy between wired and wireless
technologies and on photonic integration.
Slide 31

References
• Computer Networking A Top-Down Approach
– Kurose and Ross – A product of PEASON.
• http://www.omnisecu.com/basic-
networking/index.php
• http://www.ccse.kfupm.edu.sa/~marwan/COE
344_T062/
• http://en.wikipedia.org/wiki/Ethernet
• The INTERNET
Slide 32

THANK YOU!
The end
Slide 33

Ethernet - Networking presentation

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