advanced network 1

Advanced Network 1

Refrences

● Computer Networks, By: A.S. Tanenbbaum , Publisher: Prentice Hall ● Computer Networking: A Top-Down Approach Featuring the Internet. By: J. F. Kurose and K. W. Ross. Publisher: Addison-Wesley.

● Computer Networks, A System Approach, By: LARRY L. PETERSON & BRUCE S. DAVIE Publisher: ELSEVIER

Important Contents

● Internet Multicasting

● New Internet Transport Protocols

● Internet Quality of Service

● Multimedia Transport and

Signaling

● Voice over IP

● Mobility

Important Contents

● High-speed TCP Extensions

● Domain Name System Extensions

● Label Switching

● Measurement, Modeling, Simulation

● Software Defined Networking (SDN)

● Network Security

General Subjects

in

Computer Networks

What is a computer Network?

System of Hardware and Software for

Serial Data Communication between

independent Network Edges.

Independence: every machine(edge) can work

alone.

Data Communication: Regardless of the

Transmission Channel.

Distributed Systems vs Networks Distributed Systems:

• Users are unaware of underlying structure.

• The operating system automatically allocates jobs to

processors, moves files among various computers

without explicit user intervention.

• Multiple Devices Cooperating on some task.

Network:

• An interconnected collection of autonomous

computers able to exchange information.

• Usually require users to explicitly login onto one

machine, explicitly submit jobs remotely, explicitly

move files/data around the network.

Network Edge

Also called End system or Host.

Any Computer based machine.

Needs proper HW and SW to support

Networking.

Serial communication between edges.

Hosts: Clients/ServersHosts

Host

Client or Server.

A client is a Computer, access a sever through

the Network.

A server is a Computer, usually, responds or

gives services to many clients.

A server usually is more powerful, in

processing and storage, than clients.

Network Core A part of a computer network which

interconnects networks, providing paths for

data communication between different LANs

or sub networks.

Main parts: Switches and Routers.

Each computer-based part in Edge or Core are

called a Node.

Core Nodes

Network Cores, Switches/Routers

Types of communication

Unicast: one node (address) at each end.

Multicast: one sending node; more than one

receiving nodes (addresses).

Broadcast: one sending node; to all nodes of a

sub-network

Types of communication

Multicast and Broadcast: one-way Communication

Multicast and Broadcast: need special core nodes

Time relation between sending and receiving

Simplex: Only one-way.

Half duplex: Sending and receiving in turn,

only one at a time .

Full duplex: Possible sending and receiving

simultaneously.

Hubs are Half duplex

Time relation between sending and receiving

Half duplex: one communication channel.

Full duplex: two communication channels, physical or logical.

Problem: high number of physical channels

If a network with n nodes is to use direct links,

it needs n(n-1)/2 links.

Solution: Switching, and/or Multiple Access.

Switching Networks

Three types:

Circuit switching.

Packet Switching.

Multiple access. ( sometimes the previous two

types are considered subset of this)

Circuit Switching

A physical channel is dedicated to one

communication throughout the communication.

Mostly used in non-data communication.

Inefficient in data communication, Data usually

has Burst nature

Circuit Switching

Packet Switching

Breaking the communication information down

into packets.

Destination address contained within each

packet, plus some other redundancies.

The same physical channel can be shared

among many nodes in a network.

Each packet can take a different route to its

destination (connectionless)

Packet Switching

Packets of one session my received unordered.

Packets can have redundancies such as packet

numbers.

Multiple Access

Techniques which are used to provide

communication service to multiple users over a

single channel simultaneously.

Multiple Access

Multiple Access Methods

● Frequency Division Multiple Access (FDMA)

● Time Division Multiple Access (TDMA)

● Wavelength Division Multiple Access (WDMA)

● Code Division Multiple Access (CDMA) / Spread Spectrum Multiple Access (SSMA)

● Packet Mode Multiple Access(Packet switching)

Multiple Access

Multiple Access in Networks

Packet Mode Multiple Access(Packet

switching).

Multiple Access in Networks

Packet switching when established between two

points, such as two routers, it is like TDMA

Multiplexing with random (stochastic) time

slots!

Multiple Access vs Multiplexing

There are similarities but:

Multiple access means many can access at one time,

one sends many receive but only one is desired

receiver (if unicast), such as Ethernet.

Multiplexing is a process to combine multiple signals

for transmitting it (the combined) over a single

channel or media. Generally multiplexing combines

several lower-speed signals for transmission over a

single higher-speed connection. One sends, different

data, one receives, different data. ADSL uses a type of

Multiplexing to separate data and voice.

Multiple Access vs Multiplexing

Multiplexing: There is no possibility that two

transmitted channel will damage each other’s

data.

Multiple access: if not just between two points,

there is always the possibility of collision

between the senders data.

Multiplexing

Multiple Access & Switching

Circuit switching, FDMA, TDMA, CDMA may

be used for connection between networks,

especially when a media is shared between

computer networks and other networks(non-

data). They are not used in a computer

network.

ADSL uses a type of FDMA Multiplexing to

separate data and voice.

Layering in Computer Networks

Simplify communication.

Level abstraction in complicated

tasks(network programming).

Divide and Conquer in complex systems

(computer network).

Breaking up the sending messages into

separate components and activities. Each

component handles a different part of the

communication.

Layering in Computer Networks

Not unique definition.

The OSI 7 Layers model, more

theoretic.

The TCP/IP 5 Layers model, more

practical

OSI 7 Layers model

TCP/IP, 5 Layers model

OSI 7 Layers model vs TCP/IP, 5 Layers model

TCP/IP, 5 Layers model

Layers relation

Packets naming in layer.

Different names in different layers.

Layer 2 (Data-link): Frame, longest packet

Layer 3 (Network) Connectionless: Datagram

Layer 4 (Transport): Segment

Layer 5 (Application): Message, shortest

packet

Packets size.

Transport layer: Maximum Segment size, MSS

MSS : Maximum Segment Size, in Bytes

Network layer: Maximum Datagram size, MTU

MTU : Maximum Transmission Unit, in Bytes

Data Link layer : Maximum Frame size, MTU

Layer protocols

A set of rules for communication within a

layer(two identical layers from sender and

receiver).

Protocols at one layer are unaware of issues at

another layer.

Protocol of physical layer is physical, such as:

transmission media(fiber, copper), signal

specification, Bandwidth.

Layer Implementation

Layers (e.g. OSI model) above the transport

layer are implemented in the user area of the

Operating System.

The TCP and the IP layers are implemented in

the kernel area of the OS.

Link layer is implemented by OS Device Driver,

and NIC card(Hardware).

Physical layer is implemented by NIC card and

transmission medium.

Layer Implementation

Network categories

Based on distribution and size: WAN and LAN

In LANs, switches do routing in layer 2 (IEEE

802), or in layers 2 and 3 (IEEE 802/IP)

In WANs routers do routing in layer 3. routers

are very powerful and expensive.

In WANs for distance communication special

protocols for physical layer is needed, such as

channel coding, fiber channels, satellite channels,

WDM Multiplexing, …

Network categories A WAN, some routers, some LANs

A LAN can be as small as a router and a PC (a

core node and a host)

Internet? Internet with capital I.

Most important Computer Network.

A network with IP protocol in layer 3 and TCP

or UDP protocol in layer 4.

IP protocol is used in WANs and LANs

Local Area Network, LAN

Universal and pervasive: IEEE 802.x

IEEE 802.x

IEEE 802.x Layers

MAC Address

A 48-bit Address, such as D0-59-5C-03-8A-00

MAC Add. is unique (in World), for each NIC.

Most significant Bit: 0: Unicast, 1: Multicast; the

next bit: 0:External (LAN) Add., 1:Local

(LAN)Add.

FF-FF-FF-FF-FF-FF is Broadcast Add (in this LAN). Frames with this address are reached to every

NIC and received by that computer, on a given LAN.

IEEE 802.3 (Ethernet)

Evolution of Ethernet Technology:

1976 Original Ethernet paper published

1990 10 Mbps Ethernet over twisted pair (10BaseT)

1995 100 Mbps Ethernet

1998 1 Gbps Ethernet



2015 1 Tbps Ethernet (predicted)

2020 100 Tbps Ethernet (predicted)

Link aggregation allows to “bundle” links, e.g., four 10 Gbps

links can be bundled to perform like a single 40 Gbps link


Physical layer: Ethernet, medium: twisted wires

or fiber.

Switches have removed collisions.

Hubs (if used) possible of collision, IEEE 802.3 supports CSMA/CD.

Hubs communicate half-duplex and are used like

taps (only repeater not switch)


Switches + star topology + full-duplex

No need to CSMA/CD

Problem: buffer (of switches) overflow. If the

Rate of packets sent for a node, from other

nodes, is more than the accepting rate of that node for a long time, results: buffer overflows.

Node distance in Ethernet

From a few meters to a few 100 meters.

Ethernet Frame structure

Maximum 1572 Bytes.

Last 4 Bytes are Checksum, for error detection.

IEEE 802.11(wireless LAN or Wi-Fi)

Commercial WLAN nodes supports at least, a,

b and g.

Some versions:

Multiple Access in Wi-Fi

Communication is Half-duplex

a, g and n use Orthogonal Frequency Division

Multiple Access (OFDM); b uses Direct

Sequence Spread Spectrum (DSSS)

Multiple Access in Wi-Fi, Spread Spectrum Techniques

Frequency Hopping Spread Spectrum

(FHSS).

Direct-Sequence Spread Spectrum

(DSSS)

Orthogonal Frequency-Division

Multiplexing (OFDM)

Multiple Access in Wi-Fi, FHSS The available frequency band is divided into smaller sub-bands,

f1, f2, …, fn.

The carrier frequency changes rapidly (hopping) among the

center frequencies of these sub-bands in a predetermined order.

In this example 3 channels defined, hopping time is 200 ms.

Multiple Access in Wi-Fi, FHSS The Pseudo random generator and the seed are the same for

Transmitter and Receiver.

Multiple access: with different frequency sequences.

Multiple Access in Wi-Fi, DSSS The data stream is combined via an XOR function with a high-

speed pseudo-random numerical sequence (PRN).

For 1 and 2 Mbps DSSS the PRN code is the 11-chip Barker

sequence, which is 10110111000.

The result is: 1: 01001000111 and 0: 10110111000

Multiple Access in Wi-Fi, DSSS

The code words have unique mathematical

properties that allow them to be correctly

distinguished from one another by a receiver

even in the presence of substantial noise and

interference.

Multiple access: with different codes.

Multiple Access in Wi-Fi, OFDM OFDM divides a communication channel into a number of

equally spaced subcarriers. Multi-carrier and wide-band,

remember FDM is single-carrier.

Each subcarrier is orthogonal (independent of each other) to

every other subcarrier.

In a channel all the subcarriers are used by one source at a

given time. E.g. each channel uses N subcarriers.

Multiple Access in Wi-Fi, OFDM

Sources contend with one another at the data

link layer for access.

This is the reason why orthogonal subcarriers

are used in OFDM technology so that signals

going through different channels don’t interfere

with each other.

Multiple Access in Wi-Fi, OFDM

In OFDM technology, the bit string to be transmitted

is broken down into N (N>1) bit strings. The N bit

strings are then transmitted in parallel through N

orthogonal spaced subcarriers.

Wi-Fi channels

802.11b supports 14 channels, Half-Duplex

Channel distance: 5 MHz

Each WLAN uses one channel

Wi-Fi channels

In 802.11b channels overlap.

Best channels for adjacent WLANs are 1, 6 and 11,

otherwise increase of collisions and packet loss.

Wi-Fi channels

In 802.11a, just 8 channels without overlap. Each

WLAN, one channel Half-Duplex.

Wi-Fi problems

Problems: Hidden Nodes

and Exposed Nodes

Need resolutions.

Hidden Nodes

In an infrastructure WLAN, B is Access Point, host A and C

can not see (reach) each other, so A and C may start

communication with B, in a time.

A lot of collisions in B. Although some loss is acceptable but

it can result abnormal loss.

Exposed Node problem

In an infrastructure WLAN, A and D are Access

Points, host B sees A (not D) and C sees D (not A), B

and C are in range of each other. Each node can see

just its adjacent nodes

Exposed Node problem

If B sends to A, C will not send to D, (C sees B and

sense carrier sense). It is waste of time for C. Why

C can not send to D?

Resolution for Hidden Node and Exposed Node

Multiple Access with Collision Avoidance (MACA);

IEEE 802.11 RTS/CTS

A transmitting station sends a RTS frame to the

receiving station. The receiving station replies by

sending a CTS frame. On receipt of CTS frame, the

transmitting station begins transmission.

Any station hearing the RTS is close to the

transmitting station and remains silent long enough

for the CTS.

Any station hearing the CTS is close to the

receiving station and remains silent for a specified

time indicated in RTS/CTS frames.



IEEE 802.11 RTS/CTS

If C hears a CTS, without sending a RTS, it

understands that another host (here A) is sending

data to B and suspends transmission for a specified

time indicated in RTS/CTS frames.



IEEE 802.11 RTS/CTS

If C hears a RTS, but then doesn’t hear a CTS, it

understands that it is able to send data to D.

Resolution for Exposed Node


IEEE 802.11 RTS/CTS

Directional antenna and WLAN sectorization also

can avoid exposed node problems.

WiFi frame format

Three types: Data, Control and Management.

The bits Type and subtype in Frame Control byte

determine the type of the frame.

Wi-Fi Modes of Operation

Two types:

Infrastructure

Ad-HOC or Peer to Peer

Infrastructure mode

All communication needs to go through (AP)

AP connects to upstream network.

More than one AP is possible.

Ad Hoc mode

Each node transmits data directly to

other nodes without AP.

Infrastructure Security

Two modes: Secure and Open(without security)

Security Types: WEP(oldest), WPA, WPA2,

WPA3,

More complicate encryption , more secure.

Internetworking

Network of Networks

Connecting different networks by using

intermediary (core) devices such as routers devices.

Internetworking

Network of Networks

LANs, can, have different standards.

WANs protocols in layers 3, or 3 and 4.

The most important protocol: Internet

Internetworking

A network in layer3, or 3 and 4.

Networks Integration.

Internet

Full-Duplex

IP in layer 3.

UDP or TCP in layer 4.

IPv4, IPv6

Packet or Datagram in IPv4

IP is connectionless protocol (Complete

address on each packet; Datagram).

Each Datagram (packet) containing the

origin and destination Addresses.

The address is used to decide the next

hop at each routing point.

Packet or Datagram in IPv4

Length indicates the datagram length, max: 65535

Datagram Fragmentation and Reassembly in IPv4

Datagram must be fragmented to the new

datagrams equal to the smallest MTU of the

lower layer of the nodes (networks) it needs

to pass to reach to the destination.

In destination , the data in fields Ident, Flags

and Offset are used to Reassemble main

datagram.

Internet protocol mandates that all nodes

must support datagram with length 576,

otherwise they must fragment their frames.

Datagram Fragmentation and Reassembly in IPv6

Datagram are not fragmented in IPv6

Internet protocol mandates that all nodes

must support datagram with length 1280,

otherwise they must fragment their frames.

Addressing

IPv4; Address: 32 bits; possible add. = 232

= 4,294,967,296

IPv6; Address: 128 bits; possible add.= 2128

IPv4 Addressing

Two types: Classful and classless

Classful is becoming obsolete, and

replaced with classless.

Classful has three main classes and two

especial classes.

Classful(IPv4)

The first three bits determine the class.

Class D is for Multicast, class E is reserved.

Classful Addressing

Classful Addressing

Two parts: Network and Host

Network part is used by Routers.

Classful Addressing

Two parts: Network and Host

Class A can have to 128 Nets and 224 hosts.

Class C can have to 224 Nets and 128 hosts.

The network prefix identifies a network and the host number identifies a specific host (actually, interface on the network).

How do we know how long the network prefix is? – The network prefix is implicitly defined (see class-

based addressing)

– The network prefix is indicated by a netmask.

Network prefix and Host number

network prefix host number

Classful weakness

An address is dedicated to one user(router),

all hosts are reserved for this user. Waste of

the addresses.

Example: Address 144.144.x.x ( 144.144.0.0

to 144.144.255.255) can be routed to one

destination and can be sold to one user!

Internet growth cannot be supported.

Classless addressing and Subnetting

Replace classful addressing.

Finding Net Address (router Address) by use

of subnet Mask Address.

Basic Idea of Subnetting

Split the host number portion of an IP address into a subnet number and a (smaller) host number.

• Result is a 3-layer hierarchy

Then: • Subnets can be freely assigned within the organization

• Internally, subnets are treated as separate networks

• Subnet structure is not visible outside the organization

network prefix host number

subnet number network prefix host number

extended network prefix


Bitwise AND ands one 32 Bits IP Address and a

subnet MASK; is used to find Network Address.

Network Address = IP Address AND Subnet Mask


Host Address can be found from Net and IP addresses

Host Add. = IP Add. – Network Add.

144.16.72.57 – 144.16.64.0 = 0.0.8.57

192.168.5.130 /24 Subnet mask = 255.255.255.0

4 Subnets , 62 hosts/subnet Borrow 2 bits from host byte

Subnet A -> 192.168.5.1/26 to 192.168.5.62/26 Net ID : 192.168.5.62 & Subnet Mask = 192.168.5.0 Subnet B -> 192.168.5.65/26 to 192.168.5.126/26 Net ID : 192.168.5.126 & Subnet Mask = 192.168.5.64 Subnet C -> 192.168.5.129/26 to 192.168.5.190/26 Net ID: 192.168.5.190 & Subnet Mask = 192.168.5.128 Subnet D -> 192.168.5.193/26 to 192.168.5.254/26 Net ID: 192.168.5.254 & Subnet Mask = 192.168.5.192

192.168.5.0 = Net ID(routing)

Subnet Mask = 255.255.255.192 = /26

Classless InterDomain Routing

w.x.y.z/m

New routers use CIDR.

Makes the routing table smaller.

The same as using Subnet mask.

Addresses such as:

m or prefix shows the number of MSbs of Mask

which are 1, others are 0.

w.x.y.z is IP Address (Net Id must be extracted)


w.x.y.z/m

CIDR abandons the notion of classes.

Key Concept: The length of the network id (prefix,

m) in the IP addresses is kept arbitrary.

Consequence: Routers advertise the IP address and

the length of the prefix, m.

CIDR and Address assignments Backbone ISPs obtain large block of IP

addresses space and then reallocate portions of their address blocks to their customers.

Example: Assume that an ISP owns the address block 206.0.64.0/18,

which represents 16,384 (2(32-18)) IP addresses for sub-nets and hosts. Mask = 255.255.192.0

Suppose a client requires a sub-net with 800 host addresses.

CIDR: Assign a /22 block, e.g., 206.0.68.0/22, (one Address

From 206.0.64.0/22 to 206.0.124.0/22) 1 and allocate a block of 1,024 (210) IP addresses. e.g: 206D.0D.01000100b.0D to 206D.0D.01000111b.255D ; (1024-800 addresses are reserved for this client).

1. From 206D.0D.01000000b.0D to 206D.0D.01111100b.0D


CIDR: 32 M (225 ) Europe Addresses need only one input of routing table, 194.0.0.0/7 (In a router out

of Europe), 194=11000100; Mask = 254.0.0.0

Private IP Addresses

There are a few reserved IPv4 address spaces

which cannot be used on the internet.

These addresses cannot be routed on the

Internet, so packets containing these private

addresses are dropped by the Routers.

Private IP Addresses

These addresses are reserved as Private IP addresses.

These IPs can be used within a network, campus,

company and are private to it.

These IP addresses must be translated to some public

IP addresses using NAT process, or Web Proxy server

can be used.

Why Private Addresses:

• To overcome public(routable) IP Addresses shortage.

• It is more secure than the use of a public IP address,

private IP addresses are not directly visible on the

Internet (they are behind NAT).

IP Routing; Hop-by-Hop

The basis of today's IP networks.

Routing decisions are made at each router

independently and locally.

Algorithms of finding the shortest-paths

between nodes, such as the Dijkstra's

algorithm, can guarantee that no forwarding

loop exists in a network.

Each packet contains destination address.

Each router chooses next‐hop to destination.

IP Routing; Hop-by-Hop

Address Resolution Protocol, ARP

ARP is a procedure for mapping a dynamic IP address to a

permanent physical machine address (Media Access Control

or MAC) in a LAN.

Translate 32-bit addresses to 48-bit addresses and vice-

versa.

Translate layer 3 (IP Add.) Address to layer 2 (link layer, or

Ethernet) Address and vice-versa.

The ARP conversion table is updated every 15 minutes, (one

side Add. May change, e.g. Ethernet card in a host fails and

is replaced by a new one.

IPv6 uses the Neighbor Discovery Protocol, and its

extensions such as Secure Neighbor Discovery, rather than

ARP.

Transport Layer Protocols

The Layer 4(Transport) protocol.

Transport Layer Protocols, requirements

End-to-End: transmits the entire message

(Application layer packet) to the destination.

Therefore, it ensures the end-to-end delivery of an

entire message from a source to the destination.

Transport Layer Protocols, requirements

Give services to application layer messages.

Reliable delivery (connection oriented): provides

reliability message transfer by retransmitting the

lost and damaged packets.

Application discrimination, using port address.

Different application on end points. Working with

different application in a time.

Flow control: is used to prevent the sender from

overwhelming the receiver, or receiver overflow.

Transport layer protocols: TCP , UDP

Used in Internet. TCP/IP or TCP/UDP

Transport layer protocols: TCP , UDP

They provide Best-Effort network service, do not

provide any guarantee that data is delivered or that

delivery meets any Quality of Service (QoS).

Transport layer protocol: TCP

Connection oriented: Maintains state to provide reliable

service.

Byte-stream oriented: Handles byte streams instead of

messages

Full Duplex (needs response), inappropriate for Multicast and

Broadcast.

Flow control : Prevents sender from overrunning the receiver.

Congestion control: Prevents sender from overloading the

network (any node in the route). Uses feedback.

Uses handshake protocol like SYN, SYN-ACK, ACK .

TCP Frame

e.g. : source port, destination port and sequence

number.

Transport layer protocol: UDP

Connectionless: Does not maintains state, no reliable

service.

No response for a datagram, appropriate for

Multicast and Broadcast.

No Congestion control

No fixed order, all packets are independent of each

other.

UDP is faster ( error recovery is not attempted).

Just a single error checking mechanism (checksums).

UDP Frame

Just 8 bytes header.

Port Address or Port Number

A communication endpoint.

Used with TCP and UDP.

Provide a multiplexing service for multiple services or

multiple communication sessions at one network

address.

If clients, the port number is likely a temporary

number. If servers, the port number is likely a well-

known port number.

Some Well-Known Port numbers

Applications use proper layer 4 protocol

Performance Metrics

Macro-level

• Throughput

• Response time

• Availability

• Reliability

Micro-level

• Bandwidth

• Utilization

• Error rate

• Peak load

• Average load

Bandwidth In computer Networks, is defined in Baseband.

Ability of a transmission channel for passing a

pulse with acceptable distortion.

Maximum frequency that a channel can pass with

acceptable attenuation.

In theory a channel with infinite Bandwidth is

needed to pass a pulse.

Bandwidth = B = (1/T) Hz

Bandwidth, practical

Black pulse is passed from a channel with

Bandwidth = (1/T) Hz, red is the input of the

channel or the output of an ideal channel.

Bit Rate (BR) and Baud Rate(fs)

Bit Rate(BR): The number of bits are transferred in

a network per unit of time, in bits per second (bps).

B >= BR / 2; Minimum Nyquist Bandwidth

Baud: One baud is one electronic state change per

second.

Baud Rate(fs ): or symbol rate or modulated rate,

The number of symbols are transferred in a

network per second, in Baud or symbols/s.

Each symbol is N bits, or N bits modulated with one

symbol.

fs = BR / N; fs < = 2*Bandwidth;

QPSK Modulation: N = 2, BR <= 2*2*Bandwidth

Shannon (second) Theorem, Channel Max. capacity

C = B * log2(1+ S/N)

B is Bandwidth, S is signal (Symbol) mean power in

Watts (or volts^2), N is mean power of Noise over the

bandwidth, in Watts (or volts^2).

For digital channel (transmission), a channel coding

can be found such that Bit Rate approaches to C.

For analog transmission of digital data, a proper

modulation and a channel coding can be found such

that Bit Rate approaches to C.

Latency

The time it takes for a packet, to travel from its point of origin

to the point of destination. The sum of:

Propagation delay: is a function of distance over speed with

which the signal propagates.

Transmission delay: is a function of the packet’s length and

data rate of the link.

Processing delay: Amount of time required to process the

packet header, check for bit-level errors, and determine the

packet’s destination.

Queuing delay: Amount of time the packet is waiting in the

queue until it can be processed.

It is defined one-way and include resending (if any) in reliable

communication.

Round Trip Time (RTT) Amount of time it takes for a packet to be sent plus the

amount of time it takes for an acknowledgement of that packet

to be received. Packet loss increments RTT.

The ping utility, is a method of estimating round-trip time.

pings to Google with the round-trip time statistics at the

bottom.

Jitter

Variation in RTT.

Throughput

𝑻𝒉𝒓𝒐𝒖𝒈𝒉𝒑𝒖𝒕 =𝑵𝒆𝒕𝑴𝒆𝒔𝒔𝒂𝒈𝒆𝑷𝒂𝒄𝒌𝒆𝒕𝑺𝒊𝒛𝒆

𝑴𝒆𝒔𝒔𝒂𝒈𝒆 𝑷𝒂𝒄𝒌𝒆𝒕𝑺𝒊𝒛𝒆

𝑴𝒆𝒔𝒔𝒂𝒈𝒆𝑷𝒂𝒄𝒌𝒆𝒕𝑺𝒊𝒛𝒆

𝑻𝒓𝒂𝒏𝒔𝒇𝒆𝒓𝑻𝒊𝒎𝒆

𝑻𝒉𝒓𝒐𝒖𝒈𝒉𝒑𝒖𝒕 =𝑵𝒆𝒕𝑴𝒆𝒔𝒔𝒂𝒈𝒆𝑷𝒂𝒄𝒌𝒆𝒕𝑺𝒊𝒛𝒆

𝑻𝒓𝒂𝒏𝒔𝒇𝒆𝒓𝑻𝒊𝒎𝒆

NetMessagePacketSize = The length of end-to-end packet

without redundancies.

MessagePacketSize= The length of whole end-to-end packet.

TransferTime= RTT + message packet duration.

Packet loss and redundancies in packets, increase RTT and

reduce Throughput.

advanced network 1

Documents