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UNIT I. Introduction. Switching A switch is a mechanism that allows us to interconnect links to form a larger network. A switch is a multi-input, multi-output device, which transfers packets from an input to one or more outputs. (a) Circuit switching. (b) Packet switching.

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Switching

A switch is a mechanism that allows us to interconnect links to form a larger network. A switch is a multi-input, multi-output device, which transfers packets from an input to one or more outputs.

(a) Circuit switching. (b) Packet switching


Circuit switching
Circuit Switching

  • Seeking out and establishing a physical copper path from end-to-end

  • Circuit switching implies the need to first set upa dedicated, end-to-end path for the connection before the information transfer takes place.

  • Once the connection is made the only delay is propagation time.

    Store-and-Forward Networks (Packet Switching)

  • Intermediate processors (IMPS, nodes, routers, gateways, switches) along the path store the incoming block of data.

  • Each block is received in its entirety, inspected for errors, and retransmitted along the path to the destination. This implies buffering at the router and one transmission time per hop.



  • Basic technology the same as in the 1970s

  • One of the few effective technologies for long distance data communications

  • Frame relay and ATM are variants of packet-switching

  • Advantages:

    • flexibility, resource sharing, robust, responsive

  • Disadvantages:

    • Time delays in distributed network, overhead penalties

    • Need for routing and congestion control

      Advantages over Circuit-Switching

  • Greater line efficiency

    Many packets can go over shared link

  • Data rate conversions

    Two stations of different data rates can exchange packets.

  • Non-blocking under heavy traffic (but increased delays)


Disadvantages relative to circuit switching
Disadvantages relative to Circuit-Switching

  • Packets incur additional delay with every node they pass through

  • Jitter: variation in packet delay

  • Data overhead in every packet for routing information, etc

  • Processing overhead for every packet at every node traversed


Switching technique
Switching Technique

  • Large messages broken up into smaller packets

  • Datagram

    • Each packet sent independently of the others

    • No call setup

    • More reliable (can route around failed nodes or congestion)

  • Virtual circuit

    • Fixed route established before any packets sent

    • No need for routing decision for each packet at each node


X.25

  • X.25 is a packet-switching wide area network developed by ITU-T in 1976.

  • X.25 defines how a packet-mode terminal can be connected to a packet network for the exchange of data.

  • X.25 is what is known as subscriber network interface (SNI) protocol.

  • It defines how the user’s DTE communicates with the network and how packets are sent over that network using DCEs.


X 25 devices
X.25 Devices

  • Data Terminal Equipment (DTE)

    • Terminals, personal computers, and network hosts

    • Located on premises of subscriber

  • Data Circuit-terminating Equipment (DCE)

    • Modems and packet switches

    • Usually located at carrier facility

  • Packet Switching Exchange (PSE)

    • Switches that make up the carrier network


  • X.25 network is a packet switching network that used X.25 protocol.

  • X.25 is a standard packet switching protocol that has been widely used in WAN.

  • X.25 is a standard for interface between the host system with the packet switching network in which it defines how DTE is connected and communicates with packet switching network.

  • It uses a virtual circuit approach to packet switching (SVC and PVC) and uses asynchronous (statistical) TDM to multiplex packets.



X 25 layers
X.25 Layers protocol.

X.25 protocol specifies three layers:

  • Physical Layer (X.21)

  • Frame Layer (LAPB) (Link level)

  • Packet Layer (PLP) (Packet Layer Protocol)


X 25 mapping to osi model
X.25 mapping to OSI Model protocol.

Application

Other Services

Presentation

Session

Transport

Network

PLP

X.25 Protocol Suite

Data Link

LAPB

Physical

x.21 bis, EIA/TIA-232, EIA/TIA-449,

EIA-530, G.703


X 25 physical layers
X.25 – Physical Layers protocol.

  • Specifies the physical interface between the node (computer, terminal) and the link that connected to X.25 network.

  • Specifies a protocol called X.21 or X.21bis (interface).

  • Similar enough to other PHY layer protocols, such as EIA-232.


X 21 in phy layer of x 25
X.21 in PHY layer of X.25 protocol.

  • X.21,sometimes referred to as X21, interface is a specification for differential communications introduced in the mid 1970’s by the ITU-T. X.21 was first introduced as a means to provide a digital signaling interface for telecommunications between carriers and customer’s equipment. This includes specifications for DTE/DCE physical interface elements, alignment of call control characters and error checking, elements of the call control phase for circuit switching services, and test loops.

  • When X.21 is used with V.11, it provides synchronous data transmission at rates from 100 kbit/s to 10 Mbit/s. There is also a variant of X.21 which is only used in select legacy applications, “circuit switched X.21”. X.21 normally is found on a 15-pin D Sub connector and is capable of running full-duplex data transmissions.

  • The Signal Element Timing, or clock, is provided by the carrier (your telephone company), and is responsible for correct clocking of the data. X.21 was primarily used in Europe and Japan, for example in the Scandinavian DATEX and German DATEX-L circuit switched networks during the 1980s.



X 25 frame layer
X.25 Frame Layer protocol.

  • Provides a reliable data transfer process through data link control which used link access procedure, balanced (LAPB) protocol.

  • There are 3 categories of frame involved in the LAPB frame format:

    I-Frames – encapsulate PLP packets from the network layer and before being passed to the physical layer

    S-Frames – flow and error control in the frame layer

    U-Frames - used to set up and disconnect the links between a DTE and a DCE.

    In the frame layer, communication between a DTE - DCE involves three

    phases:

    1: Link Setup ; 2: Packet Transfer ; 3: Link Disconnect





X 25 packet layer plp
X.25 Packet layer (PLP) protocol.

  • Packet Layer Protocol (PLP)

    - It is the network layer in X.25

    - This layer is responsible for establishing the connection, transferring the data, and terminating the connection between 2 DTEs.

    - It also responsible for creating the virtual circuits and negotiating network services between two DTEs.

    - Virtual circuits in X.25 are created at the network layer (not the data link layers as in some other wide area networks such as Frame Relay and ATM)


Implementation of x 25
Implementation of X.25 protocol.

  • X.25 protocol is a packet-switched virtual circuit network.

  • Virtual Circuit in X.25 created at the network layer. unlike Frame Relay and ATM which both VC created at Data Link Layer.

  • Fig 17.7 shows an X.25 network in which 3 virtual circuits have been created between DTE A and 3 other DTEs.


Frame relay
Frame Relay protocol.


Frame relay architecture
Frame Relay Architecture protocol.

  • X.25 has 3 layers: physical, link, network

  • Frame Relay has 2 layers: physical and data link (or LAPF)

  • LAPF core: minimal data link control

    • Preservation of order for frames

    • Small probability of frame loss

  • LAPF control: additional data link or network layer end-to-end functions


Lapf core
LAPF Core protocol.

LAPF core protocol installed on all subscriber systems and on all frame relay nodes. LAPF core provides a minimal set of data link control functions

  • Frame delimiting, alignment and transparency

  • Frame multiplexing/demultiplexing

  • Inspection of frame for length constraints

  • Detection of transmission errors

  • Congestion control



  • The Flag field is a unique pattern that delimits the start and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.

  • The Address field has a default length of 2 octets and may be extended to 3 or 4 octets. It carries a data link connection identifier (DLCI) of 10,17, or 24 bits. The length of the Address field, and hence of the of the DLCI, is determined by the address field extension (EA) bits. The C/R bit is application specific and not used by the standard frame relay protocol. The remaining bits in the address field have to do with congestion control.


User data transfer
User Data Transfer and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.

  • No control field, which is normally used for:

    • Identify frame type (data or control)

    • Sequence numbers

  • Implication:

    • Connection setup/teardown carried on separate channel

    • Cannot do flow and error control

      Data transfer involves the following stages

    • Establish a logical connection between two end points, and assign a unique DLCI to the connection

    • Exchange information in data frames. Each frame includes a DLCI field to identify the connection

    • Release the logical connection


Frame relay call control
Frame Relay Call Control and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.

4 message types needed

  • SETUP

  • CONNECT

  • RELEASE

  • RELEASE COMPLETE

    A frame with DLCI = 0 contain a call control message in the information field.

    Logical Connection established by sending a SETUP message. Upon receiving the SETUP message, must reply with a CONNECT message if it accepts the connection; otherwise it responds with a RELEASE COMPLETE message. The side sending the SETUP message may assign the DLCI by choosing an unused value and including this value in the SETUP message.

    Either side may request to clear a logical connection by sending a RELEASE message. The other side, upon receipt of this message, must respond with a RELEASE COMPLETE message.


ATM and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.

  • Multi-speed network environment that provides a variety of complex network services

  • Can carry voice, data, video separately or simultaneously

  • Can be used in LANs, MANs, or WANs

  • Fixed-lenth packets (cells)

  • Allows multiple logical connections to be multiplexed

  • Minimal error and flow control capabilities

  • Connection-oriented virtual channel


Cell switched atm
Cell Switched ATM and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.

  • Similar to frame relay

  • Difference?

    • Frame relay switches variable length frames within frame relay cloud from source to destination

    • ATM switches fixed-length cells (48 byte information field, 5 byte header)

  • Based on packet switching (connection-oriented)

    • Cell sequence integrity preserved via virtual channel

    • VCC – virtual channel connection – is set up between end users, variable rate, full duplex

    • VCC also used for control

  • Information field is carried transparently through the network, with minimal error control


Protocol architecture
Protocol Architecture and end of the frame. The FCS field is used for error detection. On transmission, the FCS checksum is calculated and stored in the FCS field. On reception, the checksum is again calculated and compared to the value strode in the incoming FCS field. I there is a mismatch, then the frame is assumed to be in error and is discarded.


  • User plane : Provides for user information, along with associated controls (e.g. flow control, error control)

  • Control plane : Performs call control and connection control functions

  • Management plane : Includes plane management, which performs management functions related to a system as a whole and provides coordination between all the planes, and layer management, which performs management functions relating to resources and parameters residing in its protocol entities


Atm physical layer
ATM Physical Layer associated controls (e.g. flow control, error control)

  • Transports cells via a communications channel (either optical or electrical)

  • LAN support: 25-155 Mbps copper or fiber

  • WAN support: SONET rates over fiber

  • Physical Medium Sublayer: bit transfer, bit alignment, and copper/fiber conversions

  • Transmission Convergence Sublayer: bit/cell conversion at sending and receiving nodes


Atm layer
ATM Layer associated controls (e.g. flow control, error control)

  • Handles functions of the network layer:

  • Connection-oriented without acknowledgements

  • Two possible interfaces:

    • UNI – User-Network Interface: Boundary between an ATM network and host

    • NNI – Network-Network Interface: Between two ATM switches


Uni nni interface
UNI/NNI Interface associated controls (e.g. flow control, error control)


Atm adaptation layer aal
ATM Adaptation Layer (AAL) associated controls (e.g. flow control, error control)

  • Maps higher-layer information into ATM cells to be transported over an ATM network

  • Collects information from ATM cells for delivery to higher layers


Virtual connections
Virtual Connections associated controls (e.g. flow control, error control)

  • Virtual Channel Connection (VCC) – Full duplex virtual circuit with logical connection between source and destination – can be PVC or SVC

  • It is variable rate.

  • A Virtual path connection is a bundle of VCCs that have same endpoints, and cells flowing over all of the VCCs in a single VPC are switched along the same path.

  • Virtual Path Connection (VPC) – Semi-permanent (or customer controlled or network controlled) connection that provides a logical collection of virtual channels that have the same endpoint

  • A single virtual path supports multiple virtual channels (analogy – highway = VPC, lane = VCC)

  • It is analogous to a virtual circuit in X.25.


Vci vs vpi
VCI vs VPI associated controls (e.g. flow control, error control)

  • VPI – Virtual Path Identifier – identified in cell’s header. Cannot establish a virtual channel before virtual path

  • VCI – Virtual Channel Identifier – only have local significance – different virtual paths reuse VCIs (but VCIs on same path must be unique)


What is so special about a virtual path
What is so special about a virtual path? associated controls (e.g. flow control, error control)

  • ATM is connection-oriented, so circuit must be established before transmission

    • As route established, VPIs and VCIs are assigned

  • VPI and VCI info suffices for addressing info

  • Simplified network architecture (based on VC or VP)

    Network transport functions can be separated into those related to an individual logical connection (virtual channel) and those related to a group of logical connections (virtual path)

  • Increased network performance and reliability (fewer, aggregated entities because of simplified network architecture)

  • Reduces processing and short connection setup time

    Much of the work is done when the virtual path is set up. By reserving capacity on virtual path connection in anticipation of later call arrivals, new virtual channel connections can be established by executing simple control functions at the endpoints of the virtual path connections; no call processing is required at transit nods.

  • Enhanced network services: User may define closed user group or closed networks of virtual channel bundles


Atm connection relationships
ATM Connection Relationships associated controls (e.g. flow control, error control)


The process of setting up a virtual path connection is decoupled from the process of setting up individual virtual channel connection

  • The virtual path control mechanisms include calculating routs, allocation capacity, and storing connection state information

  • For an individual virtual channel setup, control involves checking that there is a virtual path connection to the required destination node with sufficient available capacity to support the virtual channel, with appropriate quality of service, and then storing required state information.


Call establishment using vps
Call Establishment Using VPs decoupled from the process of setting up individual virtual channel connection


Virtual Channel Connection uses decoupled from the process of setting up individual virtual channel connection

The endpoints of a VCC may be end users, network entities, or an end user and a network entity. The three uses of a VCC.

Between end users:Can be used to carry end-to-end user data: can also be used to carry control signaling between end users. A VPC between end users provides them with an overall capacity, the set of VCCs does not exceed the VPC capacity.

Between an end user and a network entity:Used for user-to-network control signaling.

Between two network entities:used for network traffic management and routing functions.


Virtual path virtual channel characteristics
Virtual Path/Virtual Channel characteristics decoupled from the process of setting up individual virtual channel connection

The virtual channel connections have the following characteristics.

  • QOS – Quality of Service– involves establishing certain parameters for a specific transmission – e.g. amount of bandwidth required for a given priority data transmission, max. amount of latency tolerated, cell loss ratio( ratio of cells lost to cells transmitted), cell delay variation

  • Switched and semi permanent virtual channel connections:A switched VCC is an on-demand connection, which requires call control signaling for setup and tearing down.

  • Cell sequence integrity:The sequence of transmitted cells within a VCC is preserved.

  • Traffic parameter negotiation and usage monitoring: Traffic parameters can be negotiated between a user and the network for each VCC.

  • VPC only

    • Virtual channel identifier restriction within VPC– some VCCs reserved for network management


  • Control Signaling decoupled from the process of setting up individual virtual channel connection

  • In ATM, a mechanism is needed for the establishment and release of VPCs and VCCs. The exchange of information involved in this process is referred to as control signaling, and takes place on separate connections from those that are being managed.

  • Semi permanent VCCs may be used for user-to-user exchange. In this case, no control signaling is required.

  • If there is no preestablished call control signaling channel, then one must be setup. For that purpose, a control signaling exchange must take place between the user and the work on some channel. Hence a permanent channel is necessary with low data rate, that cane be used to setup VCCs that can be used for call control. Such a channel is called a metasignaling channel, because the channel is used to set up signal channels.

  • The metasignaling channel can be used to set up a VCC between the user and the network for call control signaling. This user-network signaling virtual channel can the be used to set up VCCs to carry user data.

  • The metasignaling channel can also be used to set up user-to-user signaling. It can then be used to allow the two end user, without network intervention, to establish and release user-to-user VCCs to carry user data


VPCs,Three methods are defined as follows decoupled from the process of setting up individual virtual channel connection

  • AVPC can be established on a semi permanent basis by prior agreement. In this case, no control signaling is required

  • VPC establishment/release may be customer controlled. In this case, the customer uses a signaling VCC to request the VPC from the network

  • VPC establishment/release may be network controlled. In this case, the network established a VPC for its own convenience. The path may be network to network, user to network, user to user.


Atm cells
ATM Cells decoupled from the process of setting up individual virtual channel connection

  • Fixed size – 53 bytes

  • 5 octet header

  • 48 octet information field

  • Small cells reduce queuing delay for high priority cells

  • Small cells can be switched more efficiently

  • Easier to implement switching of small cells in hardware


Atm cell format
ATM Cell Format decoupled from the process of setting up individual virtual channel connection


Header format
Header Format decoupled from the process of setting up individual virtual channel connection

  • Generic flow control

    • Only at user to network interface

    • Controls flow only at this point

  • Virtual path identifier

  • Virtual channel identifier

  • Payload type

    • e.g. user info or network management

  • Cell loss priority

  • Header error control


The decoupled from the process of setting up individual virtual channel connectionGeneric Flow Control (GFC) field used to assist the customer in controlling the flow of traffic for different qualities of service.

The virtual path identifier (VPI) constitutes a routing field for the network .It is 8 bits at the user-network interface and 12 bits at the network-network interface. The latter allows support for an expanded number of VPCs internal to the network, to include those supporting subscribers and those required for network management. The virtual channel identifier (VCI) is used for routing to and from the end user.

The payload type (PT) field indicates the type of information I the information field. The table shows the interpretation of the PT bits.

First bit (0 indicates ) – information

(1 indicates) – carries network management or maintenance information. This allows insert network management cells onto a user’s VCC without impacting the user’s data.

Second bit – Congestion occurred or not

Third bit – Service data unit (SDU) type bit


PT Coding Interpretation decoupled from the process of setting up individual virtual channel connection

000 User data cell, congestion not experienced, SDU-type =0

001 User data cell, congestion not experienced, SDU-type =1

010 User data cell, congestion experienced, SDU-type =0

011 User data cell, congestion experienced, SDU-type =1

100 OAM segment associated cell

101 OAM end-to-end associated cell

110 Resource management cell

101 Reserved for future function

SDU = Service Data Unit

OAM = Operations, Administration, and Maintenance


The Cell loss priority (CLP) decoupled from the process of setting up individual virtual channel connection

0 – high priority, should not be discarded unless no other alternative is available.

1 – subject to discard within the network

This facilitates to insert extra cells (beyond the negotiated rate) into the network, with CLP 1, and delivered to the destination if the network is not congested. In caser of, congestion, and violation agreement concerning traffic it may be discarded.

Generic Flow Control

GFC field is used to control traffic flow at the user-network interface (UNI) in order to alleviate short-term overload conditions.

Flow may be

Controlled

Uncontrolled

The controlled equipment, called terminal equipment (TE), initializes two variables: TRANSMIT is a flag initialized to SET (1).

GO-CNTR = 0, GO_VALUE is either initialized to 1 or set some larger value at the time of configuration.


  • If TRANSMIT = 1, cell on uncontrolled connections may be sent at any time.

    If TRANSMIT = 0, no cells may be sent on either controlled or uncontrolled connections.

    2. If a HALT signal is received from the controlling equipment, TRANSMIT is set to 0 and remains at zero until a NO_HALT signal is received, at which time TRANSMIT is set to 1

    3. If TRANSMIT = 1 and there is no cell to transmit on any uncontrolled connection then

    • If GO_CNTR > 0, then the TE may send a cell on a controlled connection. The TE marks that cell as a cell on a controlled connection and decrements GO_CNTR.

    • If GO_CNTR = 0, then the TE may not send a cell on controlled connection.

  • The TE sets GO_CNTR to GO_VALUE upon receiving a SET signal.

    The HALT signal is used logically to limit the effective ATM data rate.


Header Error Control (HEC) sent at any time.

Fig.shows the operation of the HEC algorithm


At the initialization, the receiver’s error correction algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Atm service categories
ATM Service Categories algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • ATM is designed to transfer many different types of traffic simultaneously, including real-time voice, video, and bursty TCP traffic

  • Way in which data flow is handled depends on the characteristics of the traffic flow and requirements of the application (ex. Real-time video must be delivered within minimum variation in delay)

  • Primary service categories – real time service, non-real time service


Atm service categories1
ATM Service Categories algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

An ATM network is designed to be able to transfer many different types of traffic simultaneously, including real-time flows such as voice, video, and bursty TCP flows. The following service categories have been defined by the ATM Forum.

  • Real time

    • Constant bit rate (CBR)

    • Real time variable bit rate (rt-VBR)

  • Non-real time

    • Non-real time variable bit rate (nrt-VBR)

    • Available bit rate (ABR)

    • Unspecified bit rate (UBR)

    • Guaranteed frame rate (GFR)


Real time services
Real Time Services algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

Real-time applications typically involve a flow of information to a user that is intended to reproduce that flow at a source. For example, a user expects a flow of audio or video information to be presented in continuous, smooth fashion. A lack of continuity or excessive loss results in significant loss of quality.

Constant Bit Rate (CBR)

  • CBR Fixed data rate continuously available during the connection life time

  • Upper bound on transfer delay.

  • Tightly controlled by Peak Cell Rate (PCR), Cell Transfer Delay (CTD), and Cell Delay Variation (CDV)

  • Commonly used for uncompressed audio and video

    • Video conferencing

    • Interactive audio

    • A/V distribution (e.g. television, distance learning, pay-per-view)

    • A/V retrieval (e.g. video-on-demand, audio library)


Real time variable bit rate rt vbr
Real-Time Variable Bit Rate (rt-VBR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Time sensitive application

    • Tightly constrained delay and delay variation

  • rt-VBR applications transmit at a rate that varies with time

  • Examples include bursty voice and video

  • Can statistically multiplex connections

  • Parameters include Peak Cell Rate, Sustainable Cell Rate, and Maximum Burst Size

  • rt-VBR applications transmit at a rate that varies with time

    • e.g. compressed video

    • Produces varying sized image frames

    • Original (uncompressed) frame rate constant

    • So compressed data rate varies

  • Can statistically multiplex connections


Non real time services
Non-Real-Time Services algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Non-real-time services are intended for application that have bursty traffic characteristics and do not have high tight constraints on delay and delay variation.

    Non-Real-Time Variable Bit Rate (nrt-VBR)

  • Intended for bursty traffic with no tight constraints on delay and delay variation

  • Parameters include Peak Cell Rate, Sustainable Cell Rate, Maximum Burst Size, Cell Loss Ratio, Cell Transfer Delay

  • With this information, the network can allocate resources to provide relatively low delay and minimal loss

  • Examples include airline reservations, banking transactions


Unspecified bit rate ubr
Unspecified Bit Rate (UBR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

At any given time, the capacity is available for one or both of the following reasons

  • Not all of the total resource have been committed to CBR and VBR traffice

  • The bursty nature of VBR traffic means that, at some tiems, less than the committed capacity is being used. All of this unused capacity could be made available for the UBR service.

  • For application that can tolerate some cell loss or variable delays (non-critical apps)

  • Cells forwarded on FIFO basis

  • Do not specify traffic related service guarantees

  • Best effort service (wear your parachute)

    Examples include

  • Text/data/image transfer, messaging, distribution, retrieval

  • remote terminal ( e.g., telecommuting)


Available bit rate abr
Available Bit Rate (ABR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Bursty applications that use a reliable end-to-end protocol such as TCP can detect congestion in network by means of increased round-trip delays and packet discarding. TCP has no mechanism for causing resources within the network to be shared fairly among may TCP connections.

  • Application specifies Peak Cell Rate (PCR) and Minimum Cell Rate (MCR)

  • Resources allocated to give at least MCR

  • Spare capacity shared among all ABR sources

  • Examples include LAN interconnection and basic critical data transfer systems such as banking, defense information

  • (flying standby)


Guaranteed Frame Rate (GFR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Recently added ATM service category

  • To support IP backebone subnetworks

  • Major goal is to optimize the handling of frame-based traffic that passes from a LAN through a router onto an ATM backbone network.

  • Network elements be aware of frame or packet boundaries, whn congestion requires the discard of cells, network elements must discard all of the cells that comprise a single frame.


Atm bit rate services
ATM Bit Rate Services algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


ATM Network Transmission Parameters algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

To enable consistent definition of transmission requirements, a standard set of traffic parameters has been defined in the ATM Forum traffic handling specifications. The traffic parameters include:

Peak Cell Rate (PCR)

Maximum rate of cells accepted from the user. Generally, cells received at rates exceeding the PCR are discarded. PCR values generally specify the maximum rate for all the cells (CLP=0+1), however sometimes separate PCR values may be specified for cells with CLP=0 (high priority) and CLP=0+1 (all cells).

Maximum Cell Transfer Delay (maxCTD)

Maximum time allowed for the transfer of a cell to its destination. Cells spending a longer time in transit are considered useless to the user’s application.


Peak-to-Peak Cell Delay Variation (CDV) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

The maximum tolerable variation in the cell transit time through the network.

Sustainable Cell Rate (SCR)

The long-term average cell rate provided by the user.

Maximum Burst Size (MBS)

The maximum number of cells allowed in a single burst. Longer bursts may be discarded.

Cell Loss Ratio (CLR)

The maximum ratio of cells that may get lost in the network when the offered user’s traffic conforms to the traffic contract.

Minimum Desired Cell RAte (MDCR)

The minimum desired rate of cells for the UBR+ mode


Atm adaptation layer
ATM Adaptation Layer algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Essentially the “translation layer” between ATM layer and other layers, such as PCM and IP:

  • PCM (voice)

    • Assemble bits into cells for transmission

    • Re-assemble into smooth, constant flow of bits

  • IP

    • Map IP packets onto ATM cells

    • Fragment IP packets

  • LAPF

    • Interconnect Frame relay networks with ATM networks, integrating the two is to map LAPF frames into ATM cells. Segmenting one LAPF frame into a number of cells on transmission and reassembling the frame from cells on reception.


Aal protocols
AAL Protocols algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Adaptation layer services
Adaptation Layer Services algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Handle transmission errors

  • Segmentation and re-assembly

  • To enable larger blocks of data to be carried in the information field of ATM cells

  • Handle lost and misinserted cells (cells routed the wrong way)

  • Perform flow control and timing control


Supported application types
Supported Application types algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Four AAL protocols defined:

  • AAL 1: CBR traffic, e.g. circuit emulation (T-1 over ATM), voice over ATM, real-time video

  • AAL 2: rt-VBR traffic, e.g. MPEG voice and video

  • AAL 3/4: nrt-VBR traffic, e.g. general data service (not really used by anyone)

  • AAL 5 (successor to AAL 3/4): e.g. nrt-VBR: voice on demand; nrt-VBR: frame relay, ATM; UBR: IP over ATM


Aal 1 cbr
AAL 1(CBR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • AAL 1 is the interface between a real-time uncompressed byte stream and ATM

  • Got to be fast!

  • No convergence sublayer, only SAR sublayer

  • AAL 1 takes 46 or 47 bytes of data and puts a one or two byte header on front

  • AAL 1 header consists of following:

  • One bit pointer – tells whether this is a one byte header or a two byte header. If second byte is included, this byte tells where the data starts within the payload (in case the payload does not contain a full 46 bytes of data)

  • Three-bit sequence number – used to tell if a cell is lost or mis-inserted (which may be too late anyway for real-time)

  • Four bits of error checking on preceding 3-bit sequence number (yikes!)


Aal 2 vbr
AAL 2 (VBR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • AAL 2 format is used for compressed data, which needs to indicate where each frame of compressed data ends and begins

  • Similar to AAL 1 – no convergence sublayer, only the SAR sublayer

  • Unlike AAL 1, AAL 2 adds a header and a trailer

  • The AAL 2 format has the following fields:

  • Sequence number – same as AAL 1

  • Type field – helps identify message boundaries by indicating when a cell corresponds to the first, last, or intermediate cell of a message

  • Length field – specifies the number of bytes in the payload

  • Checksum – applied to the entire cell, including the data!


Aal3 4 ubr
AAL3/4 (UBR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Why 3 / 4 ?

    • AAL3: For connection-oriented transfer of data

    • AAL4: For connectionless transfer of data

      • All connectionless packets use the same VPI/VCI at the UNI

      • Multiplexing ID (MID) introduced to distinguish connectionless packets

  • AAL3 and AAL4 combined into AAL that can be used for connection-oriented or connectionless transfer

  • AAL3/4 allows multiple users to be multiplexed and interleaved in the same ATM VC

    • Message mode: single user message segmented into ATM payloads

    • Stream mode: one or more messages segmented into ATM payloads and delivered without indication of boundaries

    • Assured mode: error-free delivery of messages

    • Non-Assured mode: messages may be delivered in error, or not at all


Aal 5 abr
AAL 5 (ABR) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • AAL 5 packets can be very large – up to 65,535 byte payload

  • AAL 5 not designed for real-time traffic

  • SAR sublayer takes the potentially large convergence sublayer packets and breaks them into 48 byte chunks, ready for the ATM layer

  • SAR sublayer also adds a 32-bit CRC at the end of the packet, which is applied to the entire packet (see next slide for example)


Example aal 5 transmission
Example AAL 5 Transmission algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Why is atm so efficient
Why is ATM so Efficient? algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Minimal error and flow control

    • Reduces overhead of processing ATM cells

    • Reduces number of required overhead bits

  • Fixed size simplified processing at each ATM node (can be switched more efficiently – more efficient use of router)

  • Small cells reduce queuing delay

  • Minimal addressing info on each cell

  • Efficient traffic management

  • Parallelism could be incorporated into the switching system if all packets were of the same length; multiple switching elements could be working in parallel performing the same operation on different packets.


Asynchronous transfer mode atm
Asynchronous Transfer Mode (ATM) algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

Voice

Data packets

MUX

Wasted bandwidth

Images

TDM

4 3 2 1 4 3 2 1 4 3 2 1

ATM

`

4 3 1 3 2 2 1


High-Speed LANs algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

High-Speed LANs


Introduction1
Introduction algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • Fast Ethernet and Gigabit Ethernet

  • Fibre Channel

  • High-speed Wireless LANs


Characteristics of high speed lans
Characteristics of High-Speed LANs algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Standard ethernet
Standard Ethernet algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

  • The original Ethernet was created in 1976 at Xerox’s Palo Alto Research Center (PARC). Since then, it has gone through four generations


Physical layer ethernet
Physical Layer: Ethernet algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Frame transmission on a bus
Frame Transmission on a Bus algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Csma cd operation
CSMA/CD Operation algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.


Ieee 802 3 frame format
IEEE 802.3 Frame Format algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

Preamble

  • 7 octets with pattern 10101010, followed by one byte with pattern 10101011 (SFD)

  • used to synchronize receiver, sender clock rates

Note: IEEE 802.3 specifies that frame length, excluding preamble and SFD, must be between 64 and 1518 bytes. Data is padded to 1500 bytes, if necessary, to ensure that the minimum length is achieved.


Ieee 802 3 frame format1
IEEE 802.3 Frame Format algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

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

  • Length:indicates the length of data segment (min. 46 bytes, max. 1500 bytes). Note: in Ethernet this is higher layer protocol, mostly IP but others may be supported such as Novell IPX and AppleTalk)

  • LLC Data:data from next-higher layer protocol

  • Pad:used to fill out data to minimum of 46 bytes

  • FCS:CRC32 checked at receiver, if error detected, the frame is usually dropped


Ip ieee 802 3 framing

Frame Relay Frame Format algorithm is in the default mode for single-bit error correction. As each cell is receive, the HEC calculation and comparison is performed. As long as no errors are detected, the receiver remains in error correction mode. When an error is detected, the receiver will correct the error if it is a single bit error or will detect that multiple error has occurred. In either case, the receiver now moves to detection mode. The receiver remains in detection mode as long as errored cells are received. When a header is examined and found not to be in error, the receiver switches back to correction modes.

ATM Cell Format

IP & IEEE 802.3 Framing



10base5 thick ethernet
10Base5: Thick Ethernet received by all other stations.

10Base2: Thin Ethernet


10baset twisted pair ethernet
10BaseT: Twisted-Pair Ethernet received by all other stations.

10Base-F: Fiber Ethernet


Utp cabling categories
UTP Cabling Categories received by all other stations.

Category 1

Two twisted pair (4 wires), voice grade( not rated for data communications). Used with Plain Old Telephone System (POTS)

Category 2

4 twisted pair (8 wires), suitable for up to 4Mbps

Category 3

Four twisted pair (8 wires), 3 twists per foot, and rated for 16Mbps

Category 4

Two twisted pair (4 wires), voice and rated for 16Mbps

Category 5

4 twisted pair (8 wires), suitable for up to 100 Mbps

Category 5e

Four twisted pair (8 wires) and rated


Hubs ethernet hubs
Hubs: Ethernet Hubs received by all other stations.


Hubs segment connectors
Hubs: Segment Connectors received by all other stations.


Bridges and switches operation of a bridge
Bridges and Switches: Operation of a Bridge received by all other stations.


Routers rear view of cisco 1600 router
Routers: received by all other stations.Rear View of Cisco 1600 Router


Routers dsl router linksys cable modem
Routers: DSL Router (Linksys Cable Modem) received by all other stations.


Routers network connections
Routers: Network Connections received by all other stations.


Hubs and switches
Hubs and Switches received by all other stations.

Hub

  • Physical amplification and retransmission of bits (repeater)

  • Transmission from a station received by central hub and retransmitted on all outgoing lines

  • Only one transmission at a time

  • Logically, a bus

    Layer 2 Hub (Switch)

  • Incoming frame buffered and then switched to one outgoing line

  • Many transmissions at same time

  • Suppose 10Mbps transmission of two stations the throughput on the LAN is 20 Mbps


Hubs and switches1
Hubs and Switches received by all other stations.

     

High-Speed Backplane or Interconnection fabric

   


Fast ethernet
Fast Ethernet received by all other stations.

  • 100BASE-T options use the IEEE 802.3 MAC protocol and frame format

  • 100BASE-X two physical links between nodes, one for transmission and one for reception.

  • 100BASE-TX makes use of shielded twisted pair (STP) or high-quality (Category 5) unshielded twisted pair (UTP).

  • 100BASE-FX uses optical fiber.

  • Distance between station and hub is 100 to 200 m for all the specification.


Ieee 802 3 100base t option taxonomy
IEEE 802.3 100Base-T Option Taxonomy received by all other stations.

IEEE 802.3u (100 Mbps)

High-quality

cabling

Lower-quality

cabling

Note: 100Base-T specification also allows full-duplex operation.


100base x
100BASE-X received by all other stations.

  • Unidirectional data rate specification of 100Mbps over a single link ( single twisted pair, single optical fiber)

  • The encoding scheme is 4B/%B-NRZI.

  • Two physical medium specifications

    • Twisted pair 100BASE-TX use 2 pairs of twisted-pair, one for transmission and one for reception

    • Optical fiber 100BASE-FX use 2 optical fiber cables, one for transmission and one for reception


100 base t4
100 BASE T4 received by all other stations.

  • It uses four separate twisted pairs of Category 3 cable

  • Split into 3 separate data streams, each with 33 1/3 Mbps, transmitted and received using 3 pairs, and thus 2 of the pairs must be configured for bidirectional transmission.


  • Full-Duplex operation received by all other stations.

  • Traditional Ethernet is half duplex. A station can either transmit or receive a frame.

  • But 100-Mbps Ethernet ran in full-duplex mode, can transmit and receive simultaneously, and logically transfer rate is 200Mbps.

  • Mixed configuration

  • Fast Ethernet can supports a mixture of existing 10-Mbps LANs and 100-Mbps LANs.

  • Many stations attach to 10-Mbps hubs using the 10BASE-T standard.

  • The hubs are in turn connected to switching hubs that conform to 100BASE-T

  • High capacity workstations and server attach directly to these 10/100 switches.

  • 100-Mbps hubs provide a building backbone and are also connected to a router that provides connection to an outside WAN


Gigabit ethernet
Gigabit Ethernet received by all other stations.

  • CSMA/CD protocol and frame format same as 10-Mbps and 100-Mbps

  • Compatible with 10-Mbps and 100-Mbps

  • 1-Gbps LAN switch provides backbone connectivity for central server and high-speed work-group switches.

  • The specification includes the following physical layer alternatives.

    • 1000BASE-LX: This long-wavelength option supports duplex links of up to 550 m of 62.5-μm or 50- μm multimode fiber or up to 5 km of 10- μm single mode fiber.

    • 1000BASE-SX: This short-wavelength option supports duplex links of up to 275 m of 62.5-μm multimode fiber or up to 550 m using 50- μm multi mode fiber.

    • 1000BASE-CX

      • Shielded twisted pair.

      • 25 meters or less typically within wiring closet.

      • PCS (Physical Code Sublayer) includes 8B/10B encoding with 1.25 Gbps line.

      • Each link is composed of a separate shielded twisted pair running in each direction.


1000BASE-T received by all other stations.

  • Four pairs of Category 5 UTP.

  • IEEE 802.3ab ratified in June 1999.

  • Category 5, 6 and 7 copper up to 100 meters.

  • This requires extensive signal processing.


Gigabit ethernet media options
Gigabit Ethernet Media Options received by all other stations.


Gigabit ethernet example ieee 802 3z
Gigabit Ethernet Example (IEEE 802.3z) received by all other stations.


10gbps ethernet uses
10Gbps Ethernet - Uses received by all other stations.

  • High-speed, local backbone interconnection between large-capacity switches

  • Server farm

  • Campus wide connectivity

  • Enables Internet service providers (ISPs) and network service providers (NSPs) to create very high-speed links at very low cost

  • Allows construction of (MANs) and WANs

    • Connect geographically dispersed LANs between campuses or points of presence (PoPs)

  • Ethernet competes with ATM and other WAN technologies

  • 10-Gbps Ethernet provides substantial value over ATM


10gbps ethernet advantages
10Gbps Ethernet - Advantages received by all other stations.

  • No expensive, bandwidth-consuming conversion between Ethernet packets and ATM cells

  • Network is Ethernet, end to end

  • IP and Ethernet together offers QoS and traffic policing approach ATM

  • Advanced traffic engineering technologies available to users and providers

  • Variety of standard optical interfaces (wavelengths and link distances) specified for 10 Gb Ethernet

  • Optimizing operation and cost for LAN, MAN, or WAN 


10gbps ethernet advantages1
10Gbps Ethernet - Advantages received by all other stations.

  • Maximum link distances cover 300 m to 40 km

  • Full-duplex mode only

  • 10GBASE-S (short):

    • 850 nm on multimode fiber

    • Up to 300 m

  • 10GBASE-L (long)

    • 1310 nm on single-mode fiber

    • Up to 10 km

  • 10GBASE-E (extended)

    • 1550 nm on single-mode fiber

    • Up to 40 km

  • 10GBASE-LX4:

    • 1310 nm on single-mode or multimode fiber

    • Up to 10 km

    • Wavelength-division multiplexing (WDM) bit stream across four light waves


10gbps ethernet distance options log scale
10Gbps Ethernet Distance Options (log scale) received by all other stations.


Ethernet data rate distance
Ethernet Data Rate - Distance received by all other stations.


Benefits of 10 gbps ethernet over atm
Benefits of 10 Gbps Ethernet over ATM received by all other stations.

  • No expensive, bandwidth consuming conversion between Ethernet packets and ATM cells

  • Network is Ethernet, end-to-end

  • IP plus Ethernet offers QoS and traffic policing capabilities approaching that of ATM

  • Wide variety of standard optical interfaces for 10 Gbps Ethernet


Fibre channel
Fibre Channel received by all other stations.

  • In data communications, there are 2 common methods to deliver data to the processor:

    • via and I/O channel

    • via the Network

  • Fibre channel combines best of both to provide

    • the simplicity and speed of I/O channel communications

    • the flexibility and interconnectivity of network communications

  • Not a shared-medium like 802.3

    • switching fabric is point-to-point/multipoint

    • no medium access issues


Switched fibre channel network

N_Ports received by all other stations.

Also:

L_Ports &

G_Ports

F_Ports

E_Ports

Switched Fibre Channel Network


Fibre channel protocol architecture

Mapping received by all other stations.

Common Services

Framing

Transmission

Physical

Fibre Channel Protocol Architecture

  • FC-4 Mapping: mappings to IEEE 802, ATM, IP, SCSI, etc.

  • FC-3 Common Services: multicasting (multiple ports on one node), etc.

  • FC-2 Framing Protocol: framing, grouping, flow and error control

  • FC-1 Transmission Protocol: signal encoding/decoding scheme

  • FC-0 Physical Media: signaling for optical fiber, coax, STP


Fibre channel protocol architecture1
Fibre Channel Protocol Architecture received by all other stations.


Fibre channel topologies
Fibre Channel Topologies received by all other stations.

  • Point-to-point

    • no intervening fabric switches

    • no routing

  • Arbitrated loop

    • conceptually similar to token ring

    • up to 126 nodes

    • SCSI

  • Fabric, or switched

    • switched connection

    • simple for nodes to manage

    • IP


Fibre channel application example
Fibre Channel Application Example received by all other stations.

133 Mbps – 1 Gbps

Fiber, video coax,

STP

33 m – 10 km

point-to-point


Ieee 802 11 protocol architecture

(PCF) received by all other stations.

(DCF)

IEEE 802.11 Protocol Architecture

2.4 Ghz

orthogonal

FDM

6, 12, 24,

36, 48,

54 Mbps

IEEE 802.11g)

(1999)

(2003)

(1997)


Performance issues in wireless networks
Performance Issues in Wireless Networks received by all other stations.

  • Bandwidth limitation

  • High relative bit error rate (BER)

  • Higher latency

  • User mobility (handoff)

Effects on TCP congestion mechanisms and, therefore, performance and throughput?


Summary of standard ethernet
Summary of Standard Ethernet received by all other stations.


Changes in the standard
Changes in the Standard received by all other stations.

  • Bridged Ethernet: Raising bandwidth and separating collision domains


Changes in the standard1
Changes in the Standard received by all other stations.

  • Switched Ethernet: N-port bridge


Changes in the standard2
Changes in the Standard received by all other stations.

  • Full-duplex (switched) Ethernet: no need for CSMA/CD


Fast ethernet1
Fast Ethernet received by all other stations.

  • Under the name of IEEE 802.3u

    • Upgrade the data rate to 100 Mbps

    • Make it compatible with Standard Ethernet

    • Keep the same 48-bit address and the same frame format

    • Keep the same min. and max. frame length

  • MAC Sublayer

    • CSMA/CD for the half-duplex approach

    • No need for CSMA/CD for full-duplex Fast Ethernet

  • Autonegotiation: allow two devices to negotiate the mode or data rate of operation


Fast ethernet physical layer
Fast Ethernet: Physical Layer received by all other stations.

Topology

Implementation


Fast ethernet encoding
Fast Ethernet: Encoding received by all other stations.


Summary of fast ethernet
Summary of Fast Ethernet received by all other stations.


Gigabit ethernet1
Gigabit Ethernet received by all other stations.

  • Under the name of IEEE 802.3z

    • Upgrade the data rate to 1 Gbps

    • Make it compatible with Standard or Fast Ethernet

    • Keep the same 48-bit address and the same frame format

    • Keep the same min. and max. frame length

    • Support autonegotiation as defined in Fast Ethernet

  • MAC Sublayer

    • Most of all implmentations follows full-duplex approach

    • In the full-duplex mode of Gigabit Ethernet, there is no collision; the maximum length of the cable is determined by the signal attenuation in the cable.

  • Half-duplex mode (very rare)

    • Traditional: 0.512 μs (25m)

    • Carrier Extension: 512 bytes (4096 bits) min. length

    • Frame bursting to improve the inefficiency of carrier extension


Gigabit ethernet physical layer
Gigabit Ethernet: Physical Layer received by all other stations.

Topology


Gigabit ethernet physical layer1
Gigabit Ethernet: Physical Layer received by all other stations.

  • Implementation

  • Encoding


Gigabit ethernet summary
Gigabit Ethernet: Summary received by all other stations.


Ten gigabit ethernet
Ten-Gigabit Ethernet received by all other stations.

  • Under the name of IEEE 802.3ae

    • Upgrade the data rate to 10 Gbps

    • Make it compatible with Standard, Fast, and Giga Ethernet

    • Keep the same 48-bit address and the same frame format

    • Keep the same min. and max. frame length

    • Allow the interconnection of existing LANs into a MAN or WAN

    • Make Ethernet compatible with Frame Relay and ATM

  • MAC Sublayer: Only in full-duplex mode  no CSMA/CD


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