Transcript OSI

SUMMARIZE ALL
SLIDES
Presented by:
Fazilah Shahren
 Maisun Zakaria
 Mazlaine Husain
 Raziedahanin Kasim
 Sihahrihah Robani
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Wet020035
Wet020078
Wet020081
Wet020148
Wet020157
OSI,LAN,TOKEN
Mazlaine bt Husain
(wet020081)
OSI
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OSI layer:
- application,presentattion,session,transport,network,
data link,physical
Function of the layer
Peer-to-peer process:
Interface between layer
Organization of the layer
LAN
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Definition - High speed, fault-tolerant data network
- Cover a relatively small geographic area
Technologies - ethernet
- Token ring
- FDDI
Advantages & disadvantages - security and cost.
Types - server-based LAN- peer-to-peer LAN
LAN transmission Method - unicast
- multicast
- broadcast
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Topologies - Physical-bus, ring, star etc.
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Devices - repeater
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Wire/cable - UTP
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Fiber optic
- Logical-broadcast, token passing
- hub
- bridge etc
- STP
TOKEN
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simple placeholder frame that is passed from station to
station around the ring.
Access method: token passing
Priority and reservation- station of equal priority=
first come first serve
Time limit- imposes time limit (any station use the ring)
Problem: - monitor station: Token destroyed by noise- how to
solve.
Addressing: use 6bytes address
Electrical specification:
-Signaling : uses differential Manchester encoding
-data rate: up to 8 Mbps
Frame format -data/command frame
-token frame
-abort frame
Frame Relay, Asynchronous
Transfer Mode (ATM): Basic
ATM: Standard
Sihahrihah Robani
(wet020157)
Frame Relay
 Frame Relay is a networking protocol that works at the
bottom two levels of the OSI reference model : the
physical and data link layers.
 Two general categories :
> Data terminal equipment (DTEs), which include
terminals, personal computers, routers and bridges.
> Data circuit-terminating equipment (DCEs), which
transmit the data through the network and are often
carrier-owned devices.
 Frame Relay virtual circuit fall into 2 categories:
> switched virtual circuits (SVCs) - temporary
connections.
> permanent virtual circuits (PVCs) – permanently
established connections by the network provider.
Asynchronous Transfer
Mode (ATM): Basic
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ATM is cell relay protocol and allow high-speed
interconnection of all the world’s network.
ATM combines a new set of networking features
Connection oriented, based on switch technology and fixed
length cell
Uses existing cable plants
Wide range of speed and distance
Designed for LAN/MAN/WAN/MAN applications
Evolution, not revolution, from existing networks and
applications
ATM is real and there is wide participation from all
market segments
ATM STANDARDS
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3 main standard bodies
:
ITU-T
(International
Telecommunication
Union)
include topics such as the definition of the
B-ISDN protocol model, the function and
sequence of each bit in the ATM cell.
ANSI
(American National
Standard Institute
)
adopts and adds detail to the ITU-T
standards and deals with issues concerning
the unique North American transmission
requirements.
ETSI (European
deals with issues concerning the European
Telecommunications communications.
Standard Institute)
 4 industry forums currently participating :
ATM FORUM
working on standards for ATM LAN
emulation.
IETF
(Internet
Engineering Task
Force)
defining the standard of Internet such as
TCP/IP. Organized by topic into several
areas (routing, transport, security etc)
RELAY FRAME
connection -oriented protocols, involve
ISDN-based signaling, and require similar
network management functions.
SMDS Interest
Group (SIG)
working closely with the ATM Forum to
specify access to SMDS service over an
ATM UNI interface.
ATM Switching,
ATM Network
Fazilah Shahren
(WET020035)
ATM Switching
ATM Switching:
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Packet switching technology that allows voice, data, image and
video traffic to be combined in evenly sized cells for high
speed transmission over one access circuit.
Aim – to increase speed, capacity and overall performance.
Functions :
i) User plane - To relay data cells ( input ports-> appropriate
output ports)
ii)Control Plane - represents functions related to the
establishment and control of the Virtual
Paths/Virtual Channel (VP/VC)
iii) Management Plane - concerned with monitoring the
controlling networks
Architecture – generic module (Functional blocks) :
1. Input Modules
-performs by terminates the incoming signals and extracts
the ATM cell stream
2. Output Models
- prepares ATM cell a formats on the physical network.
3.Cell Switch Fabric
–to perform the routing of data cells, signaling and
management cell.
4. Connection Admission control
– sets of procedures that include actions taken by the
network to grant or deny a virtual connection.
5. Switch Management
-overall responsibility of providing key information for
managing the switch and the network.
Techniques
 Cell Switching Fabric
 to relay ATM cells
 2 major functions
a) Concentration, expansion, multiplexing/demultiplexing
of traffic
b) Routing of buffering of traffic
- 5 ATM Switching Alternatives :
1) Shared Memory Switch
2) Shared Bus Switch
3) Crossbar Switch
4) Multistage Switching
5) Banyan/Delta Switching
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Switching Element Requirement :
1. Performance -Connection Blocking
- Cell Loss, Cell Insertion
- Switching Delay
2. Information Rates
3. Broadcast
Queuing Methods :
1. Problems
2. Approaches
- Input buffers - add a queue at the switch elements
inputs
- Output Buffers – add a queue at the switch output
- Central Queuing – add a queue between the inputs
on the outputs of switch.
ATM Networking
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ATM Network - high-speed networking standard
designed to support both voice and data communications
Overview
- a set of hosts connected by ATM links to ATM Switch
- Designed to improve utilization and quality of service
(QoS) on high-traffic networks
- slotted system – better scalability
- Seamless
- support data, voice, video integration
- cheaper – fixed size, short address, simplicity
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Structure of an ATM Network
-based on the concept of two end point devices
communicating by means of intermediate switches.
- 2 types of interfaces in ATM networks :
a) User-to-Network Interface (UNI)
- connection is made up of end-point device and private
or public ATM Switch
b) Network-to-Network Interface (NNI)
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ATM Networks Interfaces - UNI
- NNI
- UNI Vs NNI
- General operation on an ATM Network
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LAN Emulation
- operation - Initialization
- Registration
- Address Resolution
- Broadcast/Unknown Server (BUS)
- allows current applications to run on ATM networks
without changes
- disadvantages – ATM is hidden from application
 LANE Components
 Virtual LANs – group of users that appear to be
interconnected by one LAN
 ATM Virtual LANs
 ATM Adaptation Layer
- purpose is to adapt the PDUs passed down from the higher
layer onto ATM cells
- 2 sublayers responsible for
- segmentation and reassembly (SAR)
- convergence sublayer (CS)
- classification of ATM Adaptation protocols guided by
considering following parameters
a) Timing Relationship – (non-) requirement for
synchronisation between the receiver and sender
b) Bit rate - constant/variable
c) Connection Mode - connection oriented/connectionless
ATM : Congestion
Control and Components
Maisun bt. Zakaria
(wet020078)
ATM : Congestion Control
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provides a good traffic management
important in high speed networks
Causes of Congestion:
1. Exhaustion of buffer space
2. Deadlock
Solve congestion control by using 2 techniques :
1. Preventive (feedback-based)
- prevent congestion BEFORE it can occur
- Preventive Techniques: Leaky bucket & Token bucket
2. Reactive (reservation-based)
- responds to congestion AFTER it occurs & then attempt to stop
it
- Reactive Techniques: Load shedding, Choke packets
ATM: Components
1)
ATM Networks
- connection-oriented.
- contains 2 basic components: an endstation, and an ATM
switch
2)
Virtual Path (VP) Switch
- Route the cell using only the VPI (Virtual Path Identifier)
- The switching table stores 4 pieces information per row:
i.
Arrival interface number
ii.
Incoming VPI
iii.
Corresponding outgoing interface number
iv.
New VPI
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Virtual Path Connection (VPC) Switch
- are provided for the purpose of user-user, user-network,
network-network information transfer.
- Advantages
*Simplified network architecture
*Increased network performance and reliability
4) ATM Switching Techniques
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iii.
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v.
Shared Memory Switch
- technique that uses a common memory for the storage
of cells and switching fabric.
Shared Bus Switch
- approach utilizes a bus or dual bus architecture to
switch cell traffic.
Crossbar Switch
- matrix-like space division technique that physically
interconnects any of the N inputs to any of the N outputs
at crosspoints.
Multistage Switching
- uses a similar concept to the crossbar switch technique.
Banyan/Delta Switching
- a concept of an interconnection of stages of switching
elements.
ATM: Architecture
ATM: Description
ATM: Issues
Raziedahanin Kasim
(Wet020148)
ATM: Architecture
(word document)
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ATM Cell Structure & Format
- Cell structure
- Header & payload
- 2 Different format
- UNI & NNI
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ATM Network Architecture
-Connection is point-to-point
-Switched based traffic
-2 types of architecture
- Private network architecture
- Public network architecture
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ATM Connection
- 2 level of connections
- Virtual channel connection (VCC)
- Virtual Path connection (VPC)
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4 ATM Architecture
- 2 components
- End point devices
- Switches
- 3 layers
- ATM Adaptation Layer
- ATM Layer
- Physical Layer
ATM: Descriptions
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Asynchronous Transfer Mode (ATM) is a connection
oriented data transmission protocol based on groups of
fixed length cells.
The basic characteristics of ATM are:
1.
Cell-based technology
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Service transparent
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Connection-oriented
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User-to-network Interface (UNI)
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Occupies one layer in network architecture
3 important layers in Layered Architecture of an ATM
network are:
1. Physical Layer: responsible for transmitting and
receiving ATM cells over a physical transport
medium.
2. ATM Layer: managing the sending and receiving of
cells between the user and the network.
3. ATM Adaptation Layer (AAL): makes it possible for
the ATM Layer to support multiple services and
traffic types.
ATM: Issues
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6.
Congestion Control
Main cause for congestion – unpredictable statistical of
traffic flow
2 types – Reactive CC & Preventive CC
Admission Control
Based on performance metrics
- link-level performance measures
- connection-level performance measures
Traffic Policing
2 mechanisms
Bit dropping method
Feedback preventive control
Traffic Analysis and Prediction
2 approaches
Based on a presumed traffic model
Based on traces of actual traffic streams
Scheduling
Used multiplexing policy