Download Computer Networks Unit -6 Advance Network Technologies

Computer Networks
Unit -6
Advance Network Technologies
By B.A. Khivsara
Asst. Prof In Computer Dept
SNJB’s KBJ COE ,Chandwad
Chapter Outline
Virtualization
Software defined network
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
What is meant by virtualization
• In computing, virtualization means to create a
virtual version of a device or resource, such as a
server, storage device, network or even an
operating system where the framework divides
the resource into one or more execution
environments.
• Even something as simple as partitioning a hard
drive is considered virtualization because you take
one drive and partition it to create two separate
hard drives.
Virtualization in networking
• When applied to a network, virtualization creates
a logical software-based view of the hardware and
software networking resources (switches, routers)
• The physical networking devices are simply
responsible for the forwarding of packets.
• While the virtual network (software) provides an
intelligent abstraction that makes it easy to deploy
and manage network services and underlying
network resources.
What are the hardware and software
elements of network virtualization?
• Network virtualization can be implemented at the
server or cluster level using hypervisor software
• You can create a virtual network on a single
system.
• The hypervisor provides the abstraction layer that
allows different types of internal networks to
mimic the physical world.
Advantages of Virtualization in Networking
• 1. Easy and cheaper to manage networks: With network
virtualization you can manage your network devices through a
single management console. You don’t need physical access to
switches, varied skills sets to manage multiple switches and
routers,.
• 2. Reduce time to provision: It helps you to deploy your
applications in a much quicker time.
• 3. Avoids limitations in current network topologies
• 4. Ease of building a fully automated cloud environment
• 5. Allows for policy based access
• 6. Analytics and easier troubleshooting
• 7. Cut down the cost to purchase core switches and routers.
Chapter Outline
Virtualization
Software defined network (SDN)
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
Traditional network node: Switch
• Typical Networking Software
 Management plane
 Control Plane – The brain/decision maker
 Data Plane – Packet forwarder
SDN Concept
• Separate Control plane and Data plane entities
 Network intelligence and state are logically centralized
 The underlying network infrastructure is abstracted from the
applications
• Execute or run Control plane software on general
purpose hardware
 Decouple from specific networking hardware
 Use commodity servers
• Have programmable data planes
 Maintain, control and program data plane state from a
central entity
• An architecture to control not just a networking device
but an entire network
Control Program
Control program operates on view of network
 Input: global network view (graph/database)
 Output: configuration of each network device
Control program is not a distributed system
 Abstraction hides details of distributed state
Chapter Outline
Virtualization
Software defined network
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
ATM: Asynchronous Transfer Mode
Overview
Protocol Architecture
AAL
ATM
• Asynchronous Transfer Mode
• ATM is the cell relay protocol designed by ATM forum and adopted by
ITU-T
• ATM uses asynchronous TDM
• Cells are transmitted along virtual circuits
• Design Goals






Large bandwidth and less susceptible to noise degradation
Interface with existing systems without lowering their effectiveness
Inexpensive implementation
Support the existing telecommunications hierarchies
Connection-oriented to ensure accurate and predictable delivery
Many functions are hardware implementable
Computer Networks
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Multiplexing using Cells
• The variety of packet sizes makes traffic unpredictable
• A cell network uses the cell as the basic unit of data
exchange
 A cell is defined as a small, fixed sized block of information
 Cells are interleaved so that non suffers a long delay
 A cell network can handle real-time transmissions
 Network operation is more efficient and cheaper
Computer Networks
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Synchronous vs. Asynchronous
TDM
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ATM Conceptual Model
Four Assumptions
1. ATM network will be organized as a hierarchy.
User’s equipment connects to networks via a UNI (User-Network
Interface).
Connections between provided networks are made through NNI
(Network-Network Interface).
2. ATM will be connection-oriented.
A connection (an ATM channel) must be established
before any cells are sent.
Networks: ATM
17
ATM Connections
two levels of ATM connections:
virtual path connections
virtual channel connections
• indicated by two fields in the cell header:
virtual path identifier
VPI
virtual channel identifier VCI
•
Networks: ATM
18
ATM Architecture
• UNI: user-to-network interface
• NNI: network-to-network interface
Computer Networks
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Virtual Connection
• Connection between two endpoints is accomplished
through
 Transmission path (TP)
 Virtual path (VP)
 Virtual circuit (VC)
• A virtual connection is defined by a pair of numbers: VPI
and VCI
Computer Networks
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VPI and VCI: Hierarchical Switching
Computer Networks
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Identifiers and Cells
Computer Networks
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ATM Layer and Headers
Computer Networks
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ATM: Asynchronous Transfer Mode
Overview
Protocol Architecture
AAL
Management plane
Higher layers
Higher layers
Plane management
User plane
Layer management
Control plane
ATM adaptation layer
ATM layer
Physical layer
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Networks: ATM
Figure 9.2
25
ATM Layers
Computer Networks
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ATM PHYSICAL LAYER
• The functions of this layer are split into two sublayers
• Transmission Convergence TC
HEC generation and verification
Cell scrambling and descrambling
Cell delineation
Path signal indication
Time phasing-pointer processing
Multiplexing
Scrambling/descrambling
Transmission frame generation/recovery
• Physical Media Dependent (PMD)
Bit timing, line coding
Physical medium
ATM LAYER
The ATM layer provides the following services:
• Cell transmission : generation, reception, validation
• Cell multiplexing/demultiplexing, cell relaying, cell
copying
• Cell payload discrimination
• Support of multiple QOS classes
• Traffic management: usage control, traffic shaping,
congestion notification
• Connection assignment and removal
• Switching
ATM Protocol Architecture
• ATM Adaptation Layer (AAL) – the protocol for
packaging data into cells is collectively referred
to as AAL.
• The ATM Adaptation Layer (AAL) is responsible
for the conversion between user's data and ATM
cells
• Must efficiently package higher level data such as
voice samples, video frames and datagram
packets into a series of cells.
Networks: ATM
29
Application Adaptation Layer (AAL)
An AAL is further divided into:
The Convergence Sublayer (CS)
manages the flow of data to and from SAR sublayer.
(Responsible for Data integration)
The Segmentation and Reassembly Sublayer
(SAR)
breaks data into cells at the sender and reassembles
cells into larger data units at the receiver.
Networks: ATM
30
ATM: Asynchronous Transfer Mode
Overview
Protocol Architecture
AAL
Application Adaptation Layer (AAL)
• Convert data from upper-layer into 48-byte data units
for the ATM cells
• AAL1 – constant bit rate (CBR) video and voice
• AAL2 – variable bit rate (VBR) stream  low-bitrate traffic an short-frame traffic such as audio
(ex: mobile phone)
• AAL3/4 – connection-oriented/connectionless data
• AAL5 – SEAL (Simple and Efficient Adaptation Layer)No sequencing and error control mechanisms
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AAL1
Computer Networks
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AAL2
Computer Networks
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AAL3/4
Computer Networks
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AAL5
Computer Networks
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Chapter Outline
Virtualization
Software defined network
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
GMPLS Outline
•Part I: MPLS
•Part II: GMPLS
Why MPLS?
• MPLS stands for: “Multi-Protocol Label
Switching”
• Packets are switched, not routed, based on labels
• Labels are filled in the packet header
• Basic operation:
 Ingress LER (Label Edge Router) pushes a label in front of the IP
header
 LSR (Label Switch Router) does label swapping
 Egress LER removes the label
Basic Idea
• MPLS allows most packets to be forwarded at
Layer 2 rather than having to be passed up to
Layer
• Each packet gets labeled on entry network by the
ingress router.
• All the subsequent routing switches perform
packet forwarding based only on those.
• Finally, the egress router removes the label(s) and
forwards the original IP packet toward its final
destination.
Basic Idea (Cont.)
• The label determines which pre-determined path
the packet will follow.
• Service providers can use MPLS to improve quality
of service (QoS) by defining latency, jitter, packet
loss and downtime.
• Today, Generalized Multi-Protocol Label Switching
(GMPLS) extends MPLS to manage time division
multiplexing (TDM), lambda switching and other
classes of switching technologies beyond packet
switching.
MPLS Operation
Part II: GMPLS
GMPLS Basics
• GMPLS (Generalized Multiprotocol Label
Switching), also known as Multiprotocol Lambda
Switching,
• is a technology that provides enhancements to
Multiprotocol Label Switching (MPLS)
• support network switching for time, wavelength,
and space switching as well as for packet
switching.
GMPLS and MPLS
• GMPLS is deployed from MPLS
 Apply MPLS control plane techniques to
optical switches and IP routing
algorithms to manage lightpaths in an
optical network
• GMPLS made some modifications on MPLS
 Separation of signaling and data channel
 Support more types of control interface
 Other enhancement
Why GMPLS?
• What we need? A common control plane
 Support multiple types of traffic (ATM, IP, SONET
and etc.)
 Support both peer and overlay models
 Support multi-vendors
 Perform fast provisioning
Basic Idea of GMPLS
• GMPLS is conceptually similar to MPLS, but instead
of using an explicit label to distinguish an LSP at
each LSR, some physical property of the received
data stream is used
• The most commonly used schemes are:
1. using the timeslot to identify the LSP, on a Time
Division Multiplexed (TDM) link
2. using the wavelength to identify the LSP, on a
Wavelength Division Multiplexed (WDM) link
3. using the fiber or port on which a packet is
received.
GMPLS Labels
Control interfaces of GMPLS
• Extend the MPLS to support more interfaces other than
packet switch
 Packet Switch Capable (PSC)
• Router/ATM Switch/Frame Reply Switch
 Time Division Multiplexing Capable (TDMC)
• SONET/SDH ADM/Digital Crossconnects
 Lambda Switch Capable (LSC)
• All Optical ADM or Optical Crossconnects (OXC)
 Fiber-Switch Capable (FSC)
• LSPs of different interfaces can be
nested inside another
PSC
TDMC
LSC
FSC
TDMC
LSC
GMPLS Control Plane Functions and Services
• GMPLS focuses mainly on the control plane services that
perform connection management for the data plane (the
actual forwarding logic).
• The GMPLS control planes four basic functions:
• Routing control—Provides the routing capability, traffic
engineering, and topology discovery
• Resource discovery—A mechanism to keep track of the
system resource availability such as bandwidth,
multiplexing capability, and ports
• Connection management— connection creation,
modification and deletion
• Connection restoration—Implements an additional level
of protection by establishing backup paths and enabling
very fast switching in case of failure.
Chapter Outline
Virtualization
Software defined network
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
Optical Communication Systems
Communication systems with light as the carrier
and optical fiber as communication medium
• Optical fiber is used to contain and guide light
waves
 Typically made of glass or plastic
•
Optical Fiber: Advantages
Capacity: much wider bandwidth
(10 GHz)
Crosstalk immunity
Immunity to static interference
Higher environment immunity
•
•
•
•
Weather, temperature, etc.
Safety: Fiber is non-metalic
•

•
•
•
No explosion
Longer lasting
Security: tapping is difficult
Economics: Fewer repeaters
Disadvantages
•
•
•
Higher initial cost in installation
Interfacing cost
More expensive to repair/maintain

Tools: Specialized and sophisticated
Optical Fiber Architecture
Input
Signal
Transmitter
Light
Converter
Source
Source-to-Fiber
Interface
Fiber-optic Cable
Fiber-to-light
Interface
Light
Detector
Receiver
Decoder
Output
Optical Fiber Architecture Components
•
Light source:
•
•
•
LED (Light Emitting Diode)
ILD (Injection Laser Diode)
Light detector:



PIN (p-type-intrinsic-n-type)
Photo Detector
Both convert light energy into current
Optical Fiber Construction
• Core – thin glass center of
the fiber where light
travels.
• Cladding – outer optical
material surrounding the
core
• Buffer Coating – plastic
coating that protects
the fiber.
About Light Rays (Angle of Reflection)
n1
a1
90
Plane of Interface
n2
a2
refraction
Glass material
with slightly
lower density
a2
Total
refraction
ain aout
Glass material
with slightly
higher density
reflection
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Types Of Optical Fiber
Optical fiber
Step Index (SI)
Single mode (SM)
Multi mode (MM)
Graded Index (GI)
Multi mode (MM)
59
Types Of Optical Fiber
Light
ray
Single-mode step-index Fiber
Multimode step-index Fiber
Multimode grade-index Fiber
Optical Fiber network uses
Wavelength-Division Multiplexing
WDM sends information through a single optical Fiber using lights
of different wavelengths simultaneously.
l1
l2
Multiplexer
Demultiplexer
l3
ln-1
ln
Laser
Optical sources
l1
l2
l3
Optical
amplifier
ln-1
ln
Laser
Optical detectors
Areas of Application
•
•
•
•
•
Telecommunications
Local Area Networks
Cable TV
CCTV
Optical Fiber Sensors
Chapter Outline
Virtualization
Software defined network
ATM(Overview, Protocol Architecture, AAL)
GMPLS
Introduction of optical networks,
Propagation of Signals in Optical Fiber
Client Layers of the Optical Layer
Client Layers of the Optical Layer
Outline
SONET/SDH
Optical Transport Network(OTN)
Ethernet (Gigabit)
Generic Framing Procedure(GFC)
IP
Multi Protocol Label Switching(MPLS)
Resilience packet ring (RPR)
Storage Area Network(SAN)
Client Layers of the Optical Layer
• The network that use optical fiber as their
underlying transmission mechanism.
• These network are called as Client Layers of the
Optical Layer.
• All client layer that we discussed here perform
time division multiplexing.
• Client N/w are divided into two types
1. Backbone N/W
2. Metro N/W
Client Layers of the Optical Layer
A. In the backbone networks
a. Synchronous Optical Network (SONET)/
Synchronous Digital Hierarchy (SDH)
b. Optical Transport Network(OTN)
c. Generic Framing Procedure(GFP)
d. Internet Protocol (IP)
e. Asynchronous Transfer Mode (ATM)
f. Multiprotocol Label Switching (MPLS)
B. In the metro networks
a. Gigabit Ethernet
b. 10-Gigabit Ethernet
c. Fiber channel
d. Resilient Packet Ring (RPR)
66
SONET/SDH
Basic Intro
Architecture
SONET Layers
SONET Frames
STS Multiplexing
SONET Networks
67
SONET/SDH
• Digital transmission standards for fiber-optic cable
• Independently developed in USA & Europe
 SONET(Synchronous Optical Network) by ANSI
 SDH(Synchronous Digital Hierarchy) by ITU-T
• Synchronous network using synchronous TDM
multiplexing
• All clocks in the system are locked to a master clock
• It contains the standards for fiber-optic equipments
• Very flexible to carry other transmission systems (DS-0,
DS-1, etc)
17-68
SONET/SDH Architecture
• Architecture of a SONET system: signals, devices, and connections
• Signals: SONET(SDH) defines a hierarchy of electrical signaling
levels called STSs(Synchronous Transport Signals, (STMs)).
Corresponding optical signals are called OCs(Optical Carriers)
17-69
SONET/SDH Architecture
• SONET devices: STS multiplexer/demultiplexer,
regenerator, add/drop multiplexer, terminals
17-70
SONET/SDH Architecture
• Connections: SONET devices are connected
using sections, lines, and paths
• Section: optical link connecting two neighbor
devices: mux to mux, mux to regenerator, or
regenerator to regenerator
• Lines: portion of network between two
multiplexers
• Paths: end-to-end portion of the network
between two STS multiplexers
17-71
SONET Layers
• SONET defines four layers: path, line, section, and
photonic(Physical)
• Path layer is responsible for the movement of a signal from its
optical source to its optical destination
• Line layers is for the movement of a signal across a physical line
• Section layer is for the movement of a signal across a physical
section, handling framing, scrambling, and error control
• Photonic layer corresponds to the physical layer of OSI model
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6.1.4 SONET/SDH Physical Layer
Application categories
a. Interoffice connection : ≤ 2km
b. Short haul : Between15km and 40km
c. Long haul : Between 40km and 80km
d. Very long haul: Between 60km and 120km
e. Ultra long haul : 160km
73
SONET Frames
• Each synchronous transfer signal STS-n is composed of 8000
frames. Each frame is a two-dimensional matrix of bytes with
9 rows by 90 × n columns.
•
Each byte in a SONET frame can carry a digitized voice channel
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SONET Frames
• In SONET, the data rate of an STS-n signal is n times the
data rate of an STS-1 signal
• In SONET, the duration of any frame is 125 μs
17-75
STS Multiplexing
•
The synchronous transport signal level-1 (STS-1) has
the basic signal rate 51.84 Mb/s
STS multiplexing/demultiplexing
SONET Network
•
Point-to-point network
•
Multipoint network
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Client Layers of the Optical Layer
Outline
SONET/SDH
Optical Transport Network(OTN)
Ethernet (Gigabit)
Generic Framing Procedure(GFC)
IP
Multi Protocol Label Switching(MPLS)
Resilience packet ring (RPR)
Storage Area Network(SAN)
Optical Transport Network (OTN)
Basic Intro
Key Functions
OTN line rates
OTN Hierarchy
Frame Structure
Optical Transport Network (OTN)
• OTN was designed to provide support for optical
networking using wavelength-division
multiplexing (WDM) unlike its
predecessor SONET/SDH.
• ITU-T Recommendation G.709 is commonly called
Optical Transport Network (OTN)
(also called digital wrapper technology or optical
channel wrapper).
Optical Transport Network (OTN)
Signals that OTN equipment processes are:
1.
2.
3.
4.
OTN
SONET/SDH
Ethernet/FibreChannel
Packets
key functions performed are:






Forward error correction (FEC) on OTN signals
Management
Protocol transparency
Asynchronous timing
Multiplexing and de-multiplexing of OTN signals
Mapping and de-mapping of non-OTN signals into and out of OTN
signals
OTN line rates compared to
SONET/SDH line rates
OTN
Line rates
SONET/SDH
Line rates
OTU 1:
2.666 Gb/s
STS-48
2.488 Gb/s
OTU 2:
10.709 Gb/s
STS-192
9.953 Gb/s
OUT 3:
43.018 Gb/s
STS-786
39.813 Gb/s
Converged transport over OTN
OTN Hierarchy
OTN Frame structure
• Frame consist of 4080 columns and 4 rows of bytes
• Frame starts from left top corner to bottom right
corner
• Each row has 16 no of FEC block with size 255 bytes.
• Overhead is in 15 & 16 column in frame
Client Layers of the Optical Layer
Outline
SONET/SDH
Optical Transport Network(OTN)
Ethernet (Gigabit)
Generic Framing Procedure(GFC)
IP
Multi Protocol Label Switching(MPLS)
Resilience packet ring (RPR)
Storage Area Network(SAN)
Ethernet
MAC layer- CSMA/CD
Point-to-Point link
LAN- topology , repeater ,VLAN , VPN
Switches –Spanning Tree & Link Aggregation
Protocol
• Ethernet Physical Layer
•
•
•
•
Gigabit Ethernet 802.3z
(a) A two-station Ethernet. (b) A multistation
Ethernet.
Gigabit Ethernet(2)
• Supports two different modes of operations
• 1> full duplex 2> half duplex
• In full duplex mode switch is used. In this contention is
not possible so CSMA/CD protocol is not used.
• In half duplex mode hub is used. In this collision is
possible so CSMA/CD protocol is used.
• Two features
1. carrier extension
2. frame bursting
Gigabit Ethernet (3)
Gigabit Ethernet cabling.
Gigabit Ethernet (4)
• Gigabit support both copper and fiber cabling
• Signaling at 1Gbps over fiber means that light source has to
be turned on and off in under 1nsec
• LED’s can not operate at this speed so lasers are used
• Three fiber diameters are permitted : 10,50 and 62.5 microns
• Two wavelengths are permitted : 0.85 and 1.3 microns
• On fiber new encoding scheme 8B/10B is used ie each 8bits
is encoded as 10 bits on fiber
• 1024 possible code words for each input is possible so two
rules are available to make the decision
1> No codeword have more than 4 identical bits in a row
2> No codeword may have more than six 0s or six 1s
Ethernet Frame Format
PRE
SOF
DA SA Length/Type
Payload
FCS
a. Basic Ethernet Frame
PRE
SOF
DA SA
VLAN Header Length/Type
b. VLAN Ethernet Frame
Payload
FCS
Ethernet Frame Format
• Preamble (PRE)-Used to indicate start of frame for
synchronization
• Start of delimiter (SOF)- indicates start of rest of
the frame
• Destination Address (DA)
• Source Address (SA)
• Frame Check Sequence (FCS) – For error detection
Client Layers of the Optical Layer
Outline
SONET/SDH
Optical Transport Network(OTN)
Ethernet (Gigabit)
Generic Framing Procedure(GFC)
IP
Multi Protocol Label Switching(MPLS)
Resilience packet ring (RPR)
Storage Area Network(SAN)
Resilience packet ring (RPR)
• It is a packet switched ring N/W that
transport IP data packet.
• Its applications are MAN & WAN
• It provide services like:




Guaranteed bandwidth
constant bit rate
low delay service and
best-effort service.
• This topology is resilient(flexible) to failure.
Resilience packet ring- Ring N/W
Ringlet 1
Ringlet 0
• Ring N/W is bidirectional formed
by two counter rotating ring
called ringlet 0 and 1
• There are 2 types of frames:
transit frame & ingress frame
• Transit frame which have
accessed a ringlet
• Ingress frame are new frames
waiting for adding into ringlet.
Resilience packet ring- QoS
• RPR supports 3 classes of traffics
1. Class A: low latency and jitter
2. Class B: Predictable latency & jitter
3. Class C: Best effort transport
Client Layers of the Optical Layer
Outline
SONET/SDH
Optical Transport Network(OTN)
Ethernet (Gigabit)
Generic Framing Procedure(GFC)
IP
Multi Protocol Label Switching(MPLS)
Resilience packet ring (RPR)
Storage Area Network(SAN)
Storage-Area Networks (SANS)
• SANs are networks used to interconnect computer
systems with other computer systems and peripheral
equipments such as disk drives, printers and tape
drives.
• A key part of SANs is Switch which provides
reconfigurable connectivity between the various
attached devices.
• SANs are typically operate at bit ranges ranging from
200 Mb/s to 10 Gb/s.
• Operate over fiber optic links.
• Fiber channel protocol become the leading SAN.
SAN Architecture
Tape drive
Switch
CPUs
Disk drive
Printer