I want ppt on high speed network for diploma electronics and communication department.
Ppt on high speed network for diploma electronics and communication department
UNIT I HIGH SPEED NETWORKS 9
Frame Relay Networks – Asynchronous transfer mode – ATM Protocol Architecture,
ATM logical Connection, ATM Cell – ATM Service Categories – AAL, High Speed
LANs: Fast Ethernet, Gigabit Ethernet, Fiber Channel – Wireless LANs: applications,
requirements – Architecture of 802.11
UNIT II CONGESTION AND TRAFFIC MANAGEMENT 8
Queuing Analysis- Queuing Models – Single Server Queues – Effects of Congestion –
Congestion Control – Traffic Management – Congestion Control in Packet Switching
Networks – Frame Relay Congestion Control.
UNIT III TCP AND ATM CONGESTION CONTROL 11
TCP Flow control – TCP Congestion Control – Retransmission – Timer Management –
Exponential RTO back off – KARN’s Algorithm – Window management – Performance
of TCP over ATM. Traffic and Congestion control in ATM – Requirements – Attributes
–Traffic Management Frame work, Traffic Control – ABR traffic Management – ABR
rate control, RM cell formats, ABR Capacity allocations – GFR traffic management.
UNIT IV INTEGRATED AND DIFFERENTIATED SERVICES 8
Integrated Services Architecture – Approach, Components, Services- Queuing Discipline,
FQ, PS, BRFQ, GPS, WFQ – Random Early Detection, Differentiated Services.
UNIT V PROTOCOLS FOR QOS SUPPORT
RSVP – Goals & Characteristics, Data Flow, RSVP operations, Protocol Mechanisms –
Multiprotocol Label Switching – Operations, Label Stacking, Protocol details – RTP –
Protocol Architecture, Data Transfer Protocol, RTCP.
TOTAL: 45 PERIODS
TEXT BOOK
1. William Stallings, “HIGH SPEED NETWORKS AND INTERNET”, Pearson
Education, Second Edition, 2002.
REFERENCES
1. Warland, Pravin Varaiya, “High performance communication networks”, Second
Edition, Jean Harcourt Asia Pvt. Ltd., , 2001.
2. Irvan Pepelnjk, Jim Guichard, Jeff Apcar, “MPLS and VPN architecture”, Cisco Press,
Volume 1 and 2, 2003.
3. Abhijit S. Pandya, Ercan Sea, “ATM Technology for Broad Band Telecommunication
Networks”, CRC Press, New York, 2004.
CS2060 HIGH SPEED NETWORKS
SCE 1 ECE
Unit I
HIGH SPEED NETWORKS
1.1 FRAME RELAY NETWORKS
Frame Relay often is described as a streamlined version of X.25, offering fewer of the robust
capabilities, such as windowing and retransmission of last data that are offered in X.25.
Frame Relay Devices
Devices attached to a Frame Relay WAN fall into the following two general categories:
• Data terminal equipment (DTE)
• Data circuit-terminating equipment (DCE)
DTEs generally are considered to be terminating equipment for a specific network and
typically are located on the premises of a customer. In fact, they may be owned by the
customer. Examples of DTE devices are terminals, personal computers, routers, and bridges.
DCEs are carrier-owned internetworking devices. The purpose of DCE equipment is to provide
clocking and switching services in a network, which are the devices that actually transmit data
through the WAN. In most cases, these are packet switches. Figure 10-1 shows the relationship
between the two categories of devices.
1.2 STANDARD FRAME RELAY FRAME
Standard Frame Relay frames consist of the fields illustrated in Figure
Figure Five Fields Comprise the Frame Relay Frame
Each frame relay PDU consists of the following fields:
1. Flag Field. The flag is used to perform high level data link synchronization which
indicates the beginning and end of the frame with the unique pattern 01111110. To
ensure that the 01111110 pattern does not appear somewhere inside the frame, bit
stuffing and destuffing procedures are used.
2. Address Field. Each address field may occupy either octet 2 to 3, octet 2 to 4, or octet 2
to 5, depending on the range of the address in use. A two-octet address field comprising
the EA=ADDRESS FIELD EXTENSION BITS and the
C/R=COMMAND/RESPONSE BIT.
3. DLCI-Data Link Connection Identifier Bits. The DLCI serves to identify the virtual
connection so that the receiving end knows which information connection a frame
belongs to. Note that this DLCI has only local significance. A single physical channel
can multiplex several different virtual connections.
4. FECN, BECN, DE bits. These bits report congestion:
o FECN=Forward Explicit Congestion Notification bit
o BECN=Backward Explicit Congestion Notification bit
o DE=Discard Eligibility bit
CS2060 HIGH SPEED NETWORKS
SCE 2 ECE
5. Information Field. A system parameter defines the maximum number of data bytes that
a host can pack into a frame. Hosts may negotiate the actual maximum frame length at
call set-up time. The standard specifies the maximum information field size
(supportable by any network) as at least 262 octets. Since end-to-end protocols
typically operate on the basis of larger information units, frame relay recommends that
the network support the maximum value of at least 1600 octets in order to avoid the
need for segmentation and reassembling by end-users.
Frame Check Sequence (FCS) Field. Since one cannot completely ignore the bit error-rate of
the medium, each switching node needs to implement error detection to avoid wasting
bandwidth due to the transmission of erred frames. The error detection mechanism used in
frame relay uses the cyclic redundancy check (CRC) as its basis.
1.3 CONGESTION-CONTROL MECHANISMS
Frame Relay reduces network overhead by implementing simple congestion-notification
mechanisms rather than explicit, per-virtual-circuit flow control. Frame Relay typically is
implemented on reliable network media, so data integrity is not sacrificed because flow control
can be left to higher-layer protocols. Frame Relay implements two congestion-notification
mechanisms:
• Forward-explicit congestion notification (FECN)
• Backward-explicit congestion notification (BECN) FECN and BECN each is controlled by
a single bit contained in the Frame Relay frame header. The Frame Relay frame header also
contains a Discard Eligibility (DE) bit, which is used to identify less important traffic that can
be dropped during periods of congestion.
1.4 FRAME RELAY VERSUS X.25
The design of X.25 aimed to provide error-free delivery over links with high error-rates. Frame
relay takes advantage of the new links with lower error-rates, enabling it to eliminate many of
the services provided by X.25. The elimination of functions and fields, combined with digital
links, enables frame relay to operate at speeds 20 times greater than X.25.
X.25 specifies processing at layers 1, 2 and 3 of the OSI model, while frame relay operates at
layers 1 and 2 only. This means that frame relay has significantly less processing to do at each
node, which improves throughput by an order of magnitude.
X.25 prepares and sends packets, while frame relay prepares and sends frames. X.25 packets
contain several fields used for error and flow control, none of which frame relay needs. The
frames in frame relay contain an expanded address field that enables frame relay nodes to
direct frames to their destinations with minimal processing .
X.25 has a fixed bandwidth available. It uses or wastes portions of its bandwidth as the load
dictates. Frame relay can dynamically allocate bandwidth during call setup negotiation at both
the physical and logical channel level.
1.5 ASYNCHRONOUS TRANSFER MODE (ATM)
Asynchronous Transfer Mode (ATM) is an International Telecommunication UnionTelecommunications
Standards Section (ITU-T) standard for cell relay wherein information for
multiple service types, such as voice, video, or data, is conveyed in small, fixed-size cells.
ATM networks are connection-oriented.
CS2060 HIGH SPEED NETWORKS
SCE 3 ECE
ATM is a cell-switching and multiplexing technology that combines the benefits of circuit
switching (guaranteed capacity and constant transmission delay) with those of packet switching
(flexibility and efficiency for intermittent traffic). It provides scalable bandwidth from a few
megabits per second (Mbps) to many gigabits per second (Gbps). Because of its asynchronous
nature, ATM is more efficient than synchronous technologies, such as time-division
multiplexing (TDM).
With TDM, each user is assigned to a time slot, and no other station can send in that time slot.
If a station has much data to send, it can send only when its time slot comes up, even if all
other time slots are empty. However, if a station has nothing to transmit when its time slot
comes up, the time slot is sent empty and is wasted. Because ATM is asynchronous, time slots
are available on demand with information identifying the source of the transmission contained
in the header of each ATM cell.
ATM transfers information in fixed-size units called cells. Each cell consists of 53
octets, or bytes. The first 5 bytes contain cell-header information, and the remaining 48 contain
the payload (user information). Small, fixed-length cells are well suited to transferring voice
and video traffic because such traffic is intolerant of delays that result from having to wait for a
large data packet to download, among other things. Figure illustrates the basic format of an
ATM cell. Figure :An ATM Cell Consists of a Header and Payload Data
1.6 ATM PROTOCOL ARCHITECTURE
ATM is almost similar to cell relay and packets witching using X.25and framerelay.like packet
switching and frame relay,ATM involves the transfer of data in discrete pieces.also,like packet
switching and frame relay ,ATM allows multiple logical connections to multiplexed over a
single physical interface. in the case of ATM,the information flow on each logical connection
is organised into fixed-size packets, called cells. ATM is a streamlined protocol with minimal
error and flow control capabilities :this reduces the overhead of processing ATM cells and
reduces the number of overhead bits required with each cell, thus enabling ATM to operate at
high data rates.the use of fixed-size cells simplifies the processing required at each ATM
node,again supporting the use of ATM at high data rates. The ATM architecture uses a logical
model to describe the functionality that it supports. ATM functionality corresponds to the
physical layer and
part of the data link layer of the OSI reference model. . the protocol referencce model shown
makes reference to three separate planes:
user plane provides for user information transfer ,along with associated controls (e.g.,flow
control ,error control).
control plane performs call control and connection control functions.
CS2060 HIGH SPEED NETWORKS
SCE 4 ECE
management plane includes plane management ,which performs management function related
to a system as a whole and provides coordination between all the planes ,and layer
management which performs management functions relating to resource and parameters
residing in its protocol entities .
The ATM reference model is composed of the following ATM layers:
• Physical layer—Analogous to the physical layer of the OSI reference model, the ATM
physical layer manages the medium-dependent transmission.
• ATM layer—Combined with the ATM adaptation layer, the ATM layer is roughly
analogous to the data link layer of the OSI reference model. The ATM layer is responsible for
the simultaneous sharing of virtual circuits over a physical link (cell multiplexing) and passing
cells through the ATM network (cell relay). To do this, it uses the VPI and VCI information in
the header of each ATM cell.
• ATM adaptation layer (AAL)—Combined with the ATM layer, the AAL is roughly
analogous to the data link layer of the OSI model. The AAL is responsible for isolating higherlayer
protocols from the details of the ATM processes. The adaptation layer prepares user data
for conversion into cells and segments the data into 48-byte cell payloads.
Finally, the higher layers residing above the AAL accept user data, arrange it into packets, and
hand it to the AAL. Figure :illustrates the ATM reference model.
1.7 LOGICALCONNECTION
Virtual channel connections (VCC)
Analogous to virtual circuit in X.25
Basic unit of switching
Between two end users
Full duplex
Fixed size cells
Data, user-network exchange (control) and network-network exchange (network
management and routing)
CS2060 HIGH SPEED NETWORKS
SCE 5 ECE
Virtual path connection (VPC)
Bundle of VCC with same end points
Simplified network architecture..
Increased network performance and reliability.
Reduced processing.
Short connection setup time..
Enhanced network services.
1.7.1 CALL ESTABLISHMENT USING VPS
1.7.2 VIRTUAL CHANNEL CONNECTION USES
Between end users
End to end user data
Control signals
VPC provides overall capacity
VCC organization done by users
Between end user and network
Control signaling
Between network entities
CS2060 HIGH SPEED NETWORKS
SCE 6 ECE
Network traffic management
Routing
1.7.3 VP/VC CHARACTERISTICS
Quality of service
Switched and semi-permanent channel connections
Call sequence integrity
Traffic parameter negotiation and usage monitoring
VPC only
Virtual channel identifier restriction within VPC
1.7.4 CONTROL SIGNALLING VCC
Done on separate connection
Semi-permanent VCC
Meta-signaling channel
Used as permanent control signal channel
User to network signaling virtual channel
For control signaling
Used to set up VCCs to carry user data
User to user signaling virtual channel
Within pre-established VPC
Used by two end users without network intervention to establish and release
user to user VCC
1.7.5 CONTROL SIGNALING VPC
Semi-permanent
Customer controlled
Network controlled
1.8 STRUCTURE OF AN ATM CELL
An ATM cell consists of a 5 byte header and a 48 byte payload. The payload size of 48 bytes
was a compromise between the needs of voice telephony and packet networks, obtained by a
simple averaging of the US proposal of 64 bytes and European proposal of
32, said by some to be motivated by a European desire not to need echo-cancellers on national
trunks.
ATM defines two different cell formats: NNI (Network-network interface) and UNI (Usernetwork
interface). Most ATM links use UNI cell format.