Section 2 Users and Networks
description
Transcript of Section 2 Users and Networks
Communications Networking:
End-users, Applications and
Network Service Classes
Professor Izhak Rubin
Electrical Engineering Department
UCLA
© 2014 - 2015 by Professor Izhak Rubin
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Communications and
Telecommunications Networking
Objective: transport of information from source end users to destination end users
Communications network End users (stationary, mobile)
Nodes (switches / routers, relays)
Links (multiple communications media; wireline; wireless)
Topological layout (tree; mesh; k-connected graph)
Quality of transport Quantity, Accuracy, timeliness,
reliability, availability, security
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Cyber-geo Map of Internet layouts Visualization Study of the NSFNET, undertaken by Donna Cox and Robert Patterson from the NCSA in 1992.
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Illustrative Network Layout
and Network Flows
A screenshot of a 3D model of
the vBNS network which
connects universities and
laboratories in the USA.
The model was created by Jeff
Brown, a researcher at MOAT,
National Laboratory for
Applied Network Research
(NLANR), USA. The model is
animated to show how traffic
flows over the links.
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Internet MCI Backbone Layout
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Network coverage using
WLANs
Abstract map of some of
the 802.11b wireless base
station nodes in central
London
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Internet
Laptop
Laptop
Laptop
Laptop
Laptop
Laptop
Laptop
Laptop
Laptop
LaptopLaptop
Laptop
Wireless Mesh Network
Mesh
AP Mesh
AP
Mesh
AP
Mesh
AP
Wired Network
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Mobile Ad hoc Wireless
Networks
Internet
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UV aided Autonomous
Mobile Backbone Network
Reference: MBNP-Simulator
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MBN with Multiple UAVs
Reference: MBNP-Simulator
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Networking Using Swarms of UAVs
SWARM 2
SWARM 1
GROUND
SENSORS
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ANet 3
Backbone Node
Gateway
ANet 1
ANet 2
ASPN 1
ASPN 2
Hierarchical Configuration of UV-aided
Mobile Backbone Network (UV-MBN)
The protocol operates in the license-free ISM band at 2.402-2.480 GHz.
To avoid interfering with other protocols that use the 2.45 GHz band, the
Bluetooth protocol divides the band into 79 channels (each 1 MHz wide) and
changes channels up to 1600 times per second.
Implementations with versions 1.1 and 1.2 reach speeds of 723.1 kbit/s.
Version 2.0 implementations feature Bluetooth Enhanced Data Rate (EDR) and
reach 2.1 Mbit/s.
Technically, version 2.0 devices have a higher power consumption, but the
three times faster rate reduces the transmission times, effectively reducing
power consumption to half that of 1.x devices (assuming equal traffic load).
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Bluetooth Networking Bluetooth is a packet-based protocol with a master-slave structure.
One master may communicate with up to 7 slaves in a piconet; all devices share the
master's clock.
Packet exchange is based on the basic clock, defined by the master, which ticks at 312.5 µs
intervals.
Two clock ticks make up a slot of 625 µs; two slots make up a slot pair of 1250 µs. In
the simple case of single-slot packets the master transmits in even slots and receives
in odd slots; the slave, conversely, receives in even slots and transmits in odd slots.
Packets may be 1, 3 or 5 slots long but in all cases the master transmit will begin in
even slots and the slave transmit in odd slots.
A master Bluetooth device can communicate with up to seven devices in a Wireless User
Group. This network group of up to eight devices is called a piconet. The devices can switch
roles, by agreement, and the slave can become the master at any time.
At any given time, data can be transferred between the master and one other device.
The master switches rapidly from one device to another in a round-robin fashion.
Simultaneous transmission from the master to multiple other devices is possible via
broadcast mode, but not used much.
The Bluetooth Core Specification allows connecting two or more piconets together to form a
scatternet, with some devices acting as a bridge by simultaneously playing the master role
in one piconet and the slave role in another.
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Bluetooth Uses
Bluetooth is a standard communications protocol primarily designed for low power consumption, with a
short range (power-class-dependent: 100 m, 10 m and 1 m, but ranges vary in practice) based on low-cost
transceiver microchips in each device. The devices do not have to be in line of sight of each other.
While the Bluetooth Core Specification does mandate minimums for range, the range of the technology is
application specific and is not limited. Manufacturers may tune their implementations to the range needed to
support individual use cases.
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Class Maximum Permitted Power Range
(approximate) mW dBm
Class 1 100 20 ~100 meters
Class 2 2.5 4 ~10 meters
Class 3 1 0 ~1 meters
Version Data Rate
Version 1.2 1 Mbit/s
Version 2.0 + EDR 3 Mbit/s
Version 3.0 + HS 24 Mbit/s
Cellular Wireless Networks:
reuse-k scheduling • Adaptive rate coordinated
scheduling mechanisms used by densely deployed BS nodes in cellular wireless networks. Reuse-1 and reuse-3
Fractional frequency reuse (FFR) (Fig. 1)
Reuse-1 for interior mobiles
Reuse-3 for exterior clients
• absolute fairness
• Proportional fairness
• throughput capacity rates optimized using adaptive scheduling schemes.
17 Prof. Izhak Rubin, EE Dept, UCLA
Reference: papers by Prof. Izhak Rubin et al.
Cellular Wireless Networks:
Directional Scheduling
The throughput metric: maximum fair throughput
capacity rate measured in unit of [bps/Hertz/cell]).
Using a FFR scheme: Reuse-1 for interior mobiles
Reuse-3 for exterior mobiles
Optimal classification (interior and exterior), jointly with:
Optimal Bandwidth Allocation (interior and exterior)
18 Prof. Izhak Rubin, EE Dept, UCLA
Relay Node
RSU
Client Node
Useful signals
Interfering signal
Vehicular Backbone Network (VBN)
20 Reference: papers by Prof. Izhak Rubin et al.
21 Reference: papers by Prof. Izhak Rubin et al.
What do we want?
Road Side Unit
But, which
car?
Let’s take a
closer look
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Reference: papers by Prof. Izhak Rubin et al.
A power line communication system for the support of home
networking.
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Reference: papers by Prof. Izhak Rubin et al.
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Video Streaming
Dynamically Adaptive
Streaming HTTP (DASH)
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3GP-DASH: Transparent end-to-end
packet switched streaming service
with 3GPP file format
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Communications Networking:
End-User
End user Host, terminal, computer, station, laptop, wireless
handset, etc.
Application Time domain and spatial distribution (scope)
Traffic Class Traffic descriptor: average rate, peak rate,
maximum burst duration
Quality of Service (QoS) requirements Per application, per traffic class
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Multi Level Traffic Model
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Traffic Engineering
Random Arrival of flows, calls, bursts, messages, packets
Random duration of underlying activity
Sharing of network storage, processing, computing, networking and communications resources – leading to: Resource contentions
Buffering / Queueing delays
Delay – throughput performance limitations
t
Duration
of activity
Resourc
e
demand
demand
demand
demand demand
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Performance Measures
Statistical; over specified period of time
Throughput: average number of information units received by destination per units time Gross and net throughput measures
Goodput = throughput of correctly (no errors) received data units
Robust Throughput = received correctly uninterrupted (credit gained upon completion of transaction [Rubin] ); e.g., no (or limited) premature breakup of route
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Delay Message and packet delay; interface boundaries (e.g., UNI)
Access delay; network (system) delay; end to end delay
Delay mean, standard deviation, jitter, packet delay variation, 99-percentile, distribution
Packet / message discard rate; call blocking ratio Offered message rate vs. departing message rate
(throughput)
Blocking probability (Grade of Service, GOS, for CS telephone networks and others that employ Call Admission Controls)
Error Rate
Reliability; availability
Performance Measures (cont.)
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Communications Network:
Service Classes
Network offered Service Classes (for QoS transport of corresponding Applications) Constant Bit Rate (CBR)
Real time Variable Bit Rate (rtVBR)
Non Real time Variable Bit Rate (nrtVBR)
Available Bit Rate (ABR)
Unspecified Bit Rate (UBR)
Best effort service
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Communications Network:
Service Classes (cont.)
Service Class Features QoS measures: packet delay, packet delay jitter,
packet discard rate; error rate; availability and reliability
QoS guarantees tied to loading by flow in accordance with traffic descriptor Call / flow admission control
Traffic policing at the User-to-Network Interface (UNI); rate control, traffic shaping
Priorities; differentiated services.
Connection oriented and connectionless operation
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Illustrative Applications and
Services over the Internet
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Broadcast and Multicast
Single message received at multiple stations
Physical layer
Physical layer broadcast
Bus networks
Link
Induced broadcast
Logical bus
Examples: local area networks
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Broadcast and Multicast
(cont.)
Network layer
Broadcast: from a source node
to all network nodes
Multicast: from a source host to
hosts that join a designated
group
Application layer
Multicast destination group by
group membership protocol
sender
receivers
sender
receivers
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Geographical Categorization
Computer Bus
Local Area Networks (LANs)
Metropolitan Area Networks (MANs)
Wide Area Networks (WANs)
Key parameter: propagation delay of signal across the communications media
Per link and end-to-end
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Multi-Media
Physical layer
Different types of communications links
Twisted pair (copper wire), coaxial, fiber-optic, radio-terrestrial, radio-satellite
Application layer
Real-time applications: voice and video
Integrated services network
Broadband-ISDN
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Topology and Connectivity
Mesh Graph
5-connected
Loop Graph (Cycle)
2-connected
Tree Graph =
Connected, no
cycles
1-connected
Star Graph
1-connected
Tree
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Topology and Connectivity
(conti.)
Graph = G = (V,E)
k (line / node) – connected = requires at least
k lines/nodes to fail to disconnect
Observe: fully connected graph with n nodes
uses n(n-1)/2 (FDX)
point-to-point lines. Need to use nodal
switching to make connections on demand.
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Graph Layouts
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Topological Layout – Graphs (1)
Graph = G = (V,E)
Connected graph has at least one path between any pair of nodes
k (line / node) – connected = remains connected under failures of k-1 (or less) lines/nodes;
Requires at least k lines/nodes to fail to disconnect
Menger’s theorem: k-connected graph iff it has k (line/node) disjoint paths between any pair of nodes
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Topological Layout - Graphs (2)
d(i,j) – distance between nodes i and j = length of i-j shortest path
Diameter (G) = max d(i,j) over all nodes.
Degree of node i = deg(i) = number of lines attached to I = number of its neighbors
Number of lines = m(G) = m; number of nodes = n(G) = n
Euler’s Theorem: 2*m = sum [deg(i)] over all nodes
For graph where deg(i) = k, m = nk/2
For k-connected graph, we have deg(i) >=k, for each node i, so that m >= nk/2.
Other connectivity measures: probabilistically based.