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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 18-14 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 18-15 Synchronous vs. Asynchronous TDM Computer Networks 18-16 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 18-19 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 18-20 VPI and VCI: Hierarchical Switching Computer Networks 18-21 Identifiers and Cells Computer Networks 18-22 ATM Layer and Headers Computer Networks 18-23 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 18-26 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 Computer Networks 18-32 AAL1 Computer Networks 18-33 AAL2 Computer Networks 18-34 AAL3/4 Computer Networks 18-35 AAL5 Computer Networks 18-36 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 58 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 17-72 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 17-74 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 17-77 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