B21DA0201_03.ppt

COMPUTER NETWORKS
S c h o o l o f C o m p u t e r S c i e n c e &
A p p l i c a t i o n s

LECTURE -1
Introduction to Network Layer
• Network layer
• Network Layer Function
• Routing
• Forwarding
3

WHAT IS NETWORK LAYER?
Definition
1. Layer 3 of OSI Referenece model.
2. Resposible for the source-to-destination delivery of
a packet. ( based on Network architecture)
3. End-to- End message delivery.
4

NETWORK LAYER
Features
1. It routes the signal through different channels from
one node to other.
2. It acts as a network controller. It manages the
Subnet traffic.
3. It decides by which route data should take.
4. It divides the outgoing messages into packets and
assembles the incoming packets into messages for
higher levels.
6

NETWORK LAYER
Function
1. Forwarding and Routing.
2. Logical addressing or IP addressing.
3. Internetworking: Communication between
different types of network.
4. Connection setup
5. Fragmentation or Defragmentation
7

FORWARDING
• Definition
Refers to routers-local action of
transfering a packet from an
input interface to the appropriate
output link interface.
8

ROUTING
• Definition
Refers to the network-wide
process that determines the end-
to-end paths that packets take
from source to destination.
9

ROUTING & FORWARDING
• Example
10

SUMMARY
Lecture-1 : Introduction to Network
Layer
Q.1 What is Network layer?
Q.2 What are the features of network layer?
Q.3 What are the function of network layer?
Q.4 What is forwarding?
Q.5 What is routing?
Q.6 What is/are the differences between forwarding
and routing?
11

ACTIVITY
Lecture-1 : Introduction to Network
Layer
Reading :
Forwarding Techniques:
http://www.brainkart.com/article/Forwarding-
Techniques_13480/
12

NETWORK
LAYER
SERVICES
• Layer-3
13

LECTURE – 2
Objectives
Network layer services
Network layer architecture
Connection Network layer services
Connectionless Network layer services
Recap
• Network layer
• Network Layer Function
• Network layer Services
Basic of computer network & Its Uses
14

SERVICES OF NETWORK LAYER
1. Provides host-to-host services to the transport
layer.
2. Provides either connection host-to-host service or
connection-less host-to-host service but not both
at a time.
3. Connection service in network layer is offered
through – virtual circuit network.
4. Connectionless service in network layer is offered
through- datagram network.
15

TYPES OF PACKET SWITCHING
NETWORK
• Example
16

NETWORK LAYER ARCHITECTURE
1. ATM : Vitual Circuit Network
2. Framerelay: Virtual Circuit Network
3. Internet : Datagram Network
17

NETWORK LAYER
Virtual Circuit - Services
1. Guaranteed delivery
2. Guaranteed delivery with bounded delay
3. In-order packet delivery
4. Guaranteed minimal bandwidth
5. Guaranteed maximum jitter
6. Security service
18

NETWORK LAYER
Datagram- Services
Provides Best effort services ( Service model)
1. No Guaranteed delivery
2. No Guaranteed delivery with bounded delay
3. No In-order packet delivery
4. No Guaranteed minimal bandwidth
5. No Guaranteed maximum jitter
19

SUMMARY
Lecture-2 : Network Layer Services
Q.1 What are the services offered by network layer in
general?
Q.2 What are the services offered by virtual circuit
network ?
Q.3 What are the services offered by datagram
network ?
Q.4 Give an example for virtual circuit network and
datagram network?
20

ACTIVITY
Lecture-2 : Network Layer Services
Reading:
1. What is the difference between function and
service?
2. What are the additional functionalities of Network
Layer?
=> Find the material/ collect points
21

NETWORK
LAYER DESIGN
ISSUES
• Layer-3
22

LECTURE - 3
Objectives
Network layer design issues
Virtual Circuit Vs Datagram
Network
Recap
• Network layer services
• Network layer architecture
• Connection Network layer services
• Connectionless Network layer services
Network Layer Design Issues
23

NETWORK LAYER DESIGN ISSUES
Challenges
1. Store and Forward packet switching
2. Services provided to Transport layer
3. Implementation of Connectionless Service
4. Implementation of Connection Service
24

STORE & FORWARD PACKET
SWITCHING
Challenge - 1
1. The host sends the packet to the nearest router.
2. This packet is stored there until it has fully arrived.
3. Once the link is fully processed by verifying the
checksum then it is forwarded to the next router till
it reaches the destination.
4. This mechanism is called “Store and Forward
packet switching”.
25

STORE & FORWARD PACKET
SWITCHING
• Problem
26

SERVICES PROVIDED TO
TRANSPORT LAYER
Challenge-2
A discussion point is whether the service should be
connection-oriented or connectionless.
Major Argument :
1. Internet community: connectionless but hosts
should do error control and flow control.
2. Telephone community: subnet should provide a
reliable ( connection services).
27

GOAL OF NETWORK LAYER SERVICE
TO TRANSPORT LAYER
Irrespective of connection or connectionless service:
1. Independent of the router technology.
2. The transport layer should be shielded from the
number, type and topology of the subnets present.
3. The network addresses made available to the
transport layer should use a uniform numbering
plan, even across LAN's and WANs.
28

IMPLEMENTATION OF
CONNECTIONLESS SERVICE
Challenges-3
1. Inconnectionless organisation
• Packets : datagrams
• Subnet : datagram subnet
2. Large packets : divided into manageable sized
packets.
3. Each packet is associated with destination address.
4. Routed independently.
5. Routing algorithms in routers manages route table 29

CONNECTIONLESS SERVICE
• Problem
30

IMPLEMENTATION OF
CONNECTION SERVICE
Challenges-4
1. Connection setup between sourc e to destination
2. Route in chosen path between source and
destination.
3. Achieved by :
a) Circuit switch connection
b) Virtual circuit switched connection
31

CONNECTION ORIENTED SERVICE
• Problem
32

DATAGRAM VS VIRTUAL CIRCUIT
• Comparison
Issue Datagram Subnet VC Subnet
Circuit setup Not needed Required
Addressing Each packet contains the full
source and destination
address
Each packet contains a short
VC number
State information Subnet does not hold state
information
Each VC requires subnet
table space
Routing Each packet is routed
independently
Route chosen during setup;
all packets of a VC follow this
route
Effects of router failures None except for packets lost
during the crash
All VC's that passed through
the failed router are
terminated
Quality of service Difficult to guarantee Easy if enough resources
can be allocated during the
setup procedure
Congestion control Difficult Easy if enough buffers can
33

SUMMARY
Lecture-3 : Network Layer Design Issues
Q.1 What is store and forward in computer network?
Q.2 What is the conflict between internet and
telephone community?
Q.3 What are the design issues of network layer?
Q.4 How network layer connection service is
implemented?
Q.5 How network layer connectionless service is
implemented?
Q.6 What are the differences between datagram
34

ACTIVITY
Lecture-3 : Network Layer Design Issues
Reading :
What’s inside router?
http://www2.ic.uff.br/~michael/kr1999/4-
network/4_06-inside.htm
Trade offs:
• router memory space versus bandwidth
• setup time versus address parsing time
=> Find the material / collect points
35

ROUTING
• Network layer Functionality
36

LECTURE - 4
Objectives
Routing
Routing Activities
Routing on Connection types
Role of IP addressing in routing
Recap
• Network layer design issues
• Virtual Circuit Vs Datagram Network
Routing
37

ROUTING
Concept
1. Routing = building maps and giving direction.
2. Vs Routing is the act of moving information across
an internetwork from a source to a destination.
3. Routers are networking devices which performs
routing.
38

ROUTING ACTIVITIES
• 2 activities
Determining optimal
routing paths and
transporting information
groups (typically called
packets) through an
internetwork.
Although packet switching is
relatively straightforward, path
determination can be very
complex.
39

ROUTING IS APPLIED TO WHAT
TYPE OF CONNECTION?
ROUTING=> WHEN APPLIED TO
VC=> DECISION OF ROUTING ARE
MADE WHEN CIRCUIT IS BEING SET
UP
ROUTING=> WHEN APPLIED TO
DATAGRAM=> THEN ROUTING
DECISION NEED TO MAKE FOR
EACH ARRIVING PACKET.
40

ROLE OF IP ADDRESSES IN
ROUTING
Location is
represented by an IP
address.
Path choice is based
on location.
Unique addressing
allows communication
between end stations.
41

PATH DETERMINATION
Importance-1
• Routing protocols use metrics to evaluate what path
will be the best for a packet to travel.
• A metric is a standard of measurement, that is used
by routing Protocols/algorithms to determine the
optimal path to a destination.
42

PATH DETERMINATION
Importance- 2
• To aid the process of path determination, routing
protocols/algorithms initialize and maintain routing
tables, which contain route information.
• Route information varies depending on the routing
algorithm used.
• Routers compare metrics to determine optimal
routes, and these metrics differ depending on the
design of the routing algorithm used.
43

ROUTING METRICS
Types
1. Hop count or path length : counts the number of
routers a packet must traverse
2. Bandwidth: preferring the path with highest
bandwidth
3. Load: traffic utilization on a link
4. Delay: time for a packet to traverse a path
5. Reliability: probability of a link failure
6. Cost: determined by IOS or administrator to
indicate preference for a route
44

SUMMARY
Lecture - 4 : Routing
Q.1 What is Routing?
Q.2 What is Router ?
Q.3 What are the activities of routing?
Q.4 Routing is applied for what types of connection?
Q.5 What is the role of IP addressing in routing?
Q.6 How optimal path is determined by routing?
Q.7 What are the parameters used for routing?
45

ACTIVITY
Lecture-4 : Routing
Reading:
Router Characteristics and Router Protocols
https://ecomputernotes.com/computernetworkingnote
s/communication-networks/routers
46

TYPES OF
ROUTING
• Network layer Functionality
47

LECTURE - 5
Objectives
Routing Properties
Types of Routing
Static Routing
Dynamic Routing
Adaptive Vs Non-Adaptive Routing
Recap
• Routing
• Routing Activities
• Routing on Connection types
• Role of IP addressing in routing
Types of Routing
48

ROUTING PROPERTIES
Design Goals
Routing algorithms often have one or more of the following
design goals:
1. Correctness- routing done properly and reach their
proper destination.
2. Simplicity - low overhead
3. Robustness – recover from h/w and s/w failures.
4. Stability – stable in all circumstances.
5. Optimality – throughput and minimizing packet delay.
6. Fairness – fair chance for every node to transmit packets.
7. Rapid convergence – Decrease delay-time.
49

ROUTING ALGORITHM
• Concept
It’s a part of the network layer software
responsible for deciding which output line
an incominh packet should be transmiited
on.
50

TYPES OF ROUTING
Categories
1. Adaptive versus Non-Adaptive
2. Static versus dynamic
3. Flat versus hierarchical
4. Intra-domain versus inter-domain
5. Cast Routing : unicast, broadcast, multicast, any cast
51

STATIC ROUTING PROTOCOL
Type -1
1. Configured manually
2. Specifies network address and subnet mask of
remote network, and IP address of next hop router
or exit interface
3. Use static routes when: – Network only consists of
few routers – Network is connected to Internet only
through one ISP
52

MERITS OF STATIC ROUTING
1. Minimal CPU processing
2. Easy to configure
3. Easier for administrator to understand
53

DEMERITS OF STATIC ROUTING
1. Configuration and maintenance is time consuming
2. Does not scale well with growing networks
3. Requires complete knowledge of the whole
network for proper implementation
54

DYNAMIC ROUTING PROTOCOL
Type-2
Added to routing table by using a dynamic routing
protocol
1. Used by routers to share information about the
reach ability and status of remote networks
2. Perform several activities:
– Network discovery
– Updating and maintaining routing tables
55

MERITS OF DYNAMIC ROUTING
1. Less administrative overhead when adding or
deleting a network
2. Protocols automatically react to the topology
changes
3. More scalable
56

DEMERITS OF DYNAMIC ROUTING
1. Router resources are used (CPU cycles, memory and
link bandwidth)
2. More administrator knowledge is required for
configuration, verification and troubleshooting
57

ADAPTIVE & NONADAPTIVE
ROUTING
• Comparison
Feature Adaptive Non-Adaptive
Define Constructs the routing
table based on the
network conditions.
Constructs the static table
Usage Dynamic routing Static routing
Routing decision Based on network
topology & traffic
Based on static table
Examples Distance-vector, Link-
state, Centralized ,
Distributed etc
Flooding
Shortest path
Complexity Complex Simple
58

SUMMARY
Lecture-5 : Types of Routing
Q.1 What are the types of routing?
Q.2 What is adaptive and non-adaptive routing
algorithm?
Q.3 What is static and dynamic routing algorithm?
Q.4 Comparison between adaptive routing and non-
adaptive routing.
59

ACTIVITY
Lecture-5 :Types of Routing
Reading:
1. Centralized /Global versus Decentralized/
Distributed.
2. Single-path versus Multipath
3. Host-intelligent versus Router-intelligent
4. Ad-hoc Routing
60

ROUTING
TAXONOMY
• Classification
61

LECTURE - 6
Objectives
Routing Taxonomy
Flooding
Shortest path Algorithm
Dijkstra Algorithm
Recap
• Routing Properties
• Types of Routing
• Static Routing
• Dynamic Routing
• Adaptive Vs Non-Adaptive Routing
Routing Taxonomy
62

ROUTING TAXONOMY
• Classification
Wired Routing Algorithm
Static Routing
Interior Routing Exterior Routing
Dynamic Routing
DV Routing L-S Routing
BGP
RIP,
IGRP
Shortest Path,
Flooding
OSPF
IS-IS
Hybrid Routing
EIGRP
63

FLOODING
Non-adaptive Routing - Concept
1. Requires no network information like topology,
load condition ,cost of different path.
2. Every incoming packet to a node is sent out on
every outgoing like except the one it arrived on.
64

FLOODING
Characteristics
1. All possible routes between Source and Destination
is tried. A packet will always get through if path
exists
2. As all routes are tried, there will be atleast one
route which is the shortest
3. All nodes directly or indirectly connected are visited
65

FLOODING
Advantages
1. Highly Robust, emergency or immediate messages
can be sent (eg military applications)
2. Set up route in virtual circuit
3. Flooding always chooses the shortest path
4. Broadcast messages to all the nodes
66

FLOODING
Limitations
1. Flooding generates vast number of duplicate
pakects
2. Suitable damping mechanism must be used
67

SHORTEST PATH ALGORITHM
Concept
1. Classic Problem
2. Single shortest path : Dijkstra Algorithm
3. All-pair shortest path : Floyd’s Warshall’s Algorithm
4. Approach : Greedy approach
5. Implemented : weighted graph
68

DIJKSTRA ALGORITHM:
Slide-1
function Dijkstra(Graph, source):
create vertex set Q
for each vertex v in Graph:
dist[v] ← INFINITY
prev[v] ← UNDEFINED
add v to Q
dist[source] ← 0
69

DIJKSTRA ALGORITHM:
Slide-2
while Q is not empty:
u ← vertex in Q with min dist[u]
remove u from Q
for each neighbor v of u: // only v that are
still in Q
alt ← dist[u] + length(u, v)
if alt < dist[v]:
dist[v] ← alt
prev[v] ← u
return dist[], prev[]
70

SHORTEST PATH ALGORITHM
• The first 5 steps used in computing the shortest path from A to D. The
arrows indicate the working node.
71

SUMMARY
Lecture-6 : Routing Taxonomy
Q.1 What is static routing protocol?
Q.2 What is Flooding?
Q.3 What is shortest path algorithm?
Q.4 Explain Dijkstra Algorithm.
72

ACTIVITY
Lecture-6 : Routing Taxonomy
Video:
Shortest path routing algorithm
• https://www.youtube.com/watch?v=nieg8XQQ7i0
• https://www.youtube.com/watch?v=OGsPQy-lM1w
73

DISTANCE
VECTOR
ROUTING
• Classification
74

LECTURE - 7
Objectives
Distance-Vector Routing
DV Routing Features
Bellman-Ford Algorithm
Recap
• Routing Taxonomy
• Flooding
• Shortest path Algorithm
• Dijkstra Algorithm
Distance Vector Routing
75

DISTANCE-VECTOR ROUTING
PROTOCOL
Concept
1. Dynamic routing protocol.
2. Determines the best and most efficient routes for
data packets
3. Parametres: distance & direction (Vector)
4. Distance: the number of steps or hosts
5. Direction: the point data leaving from port to data
reaching to the port.
6. Algorithm: Bellman-Ford Algorithm or Ford-
Fulkerson Algorithm.
76

PROTOCOL
Features
1. Creates automatically routing tables.
2. Algorithm in router exchange its routing table with
each of its neighbours.
3. Merges : existing routing table + received routing
table
4. Performed dynamically after a fixed time interval by
default.
5. Limitation => significant link overhead.
77

BELLMAN-FORD ALGORITHM
Single source shortest path
• Bellman-Ford(G,w,s)
1. Intilialize single source (G,s)
2. for i=1 to |G.v|-1
3. for each edge (u,v) belongs to G.E
4. relax (u,v,w) =>function
5. for each edge(u,v) belongs to G.E
6. If v.d>u.d+w(u,w)
7. return false( no negative cycle)
8. return true.
78

BELLMAN-FORD ALGORITHM
Single source shortest path
relax(u,v,w) => function
1. If v.d>u.d+w(u,v)
2. v.d=u.d+w(u,v)
3. v.p=u
Here shortest path to reach V when use edge u->v
Here
1. v.d= distance from source to v.
2. w(u,v) = weight of edge u->v
3. v.p= predecessor of v.
79

PROTOCOL
Information
Stored at Node
Distance to Reach Node
A B C D E F G
A 0 1 1 ∞ 1 1 ∞
B 1 0 1 ∞ ∞ ∞ ∞
C 1 1 0 1 ∞ ∞ ∞
D ∞ ∞ 1 0 ∞ ∞ 1
E 1 ∞ ∞ ∞ 0 ∞ ∞
F 1 ∞ ∞ ∞ ∞ 0 1
G ∞ ∞ ∞ 1 ∞ 1 0
Information
Stored at Node
Distance to Reach Node
A B C D E F G
A 0 1 1 2 1 1 2
B 1 0 1 2 2 2 3
C 1 1 0 1 2 2 2
D 2 2 1 0 3 2 1
E 1 2 2 3 0 2 3
F 1 2 2 2 2 0 1
G 2 3 2 1 3 1 0 85

SUMMARY
Lecture-7 : Distance Vector Routing
Q.1 What is dynamic routing protocol?
Q.2 What is distance-vector routing protocol?
Q.3 What are the features of distance-vector routing
protocol?
Q.4 What is Bellman-Ford algorithm?
Q.5 Explain Bellman-ford algorithm.
86

ACTIVITY
Lecture-7 : Distance Vector Routing
Video:
Bellman-ford : Negative weights allowed but not
negative cycle
https://www.youtube.com/watch?v=YbbGemzQ5ok
87

LINK-STATE
ROUTING
• Classification
88

LECTURE – 8
Objectives
Limitation of DV Routing
Link-State Routing
LS Routing Features & limitations
Shortest path first Algorithm
Recap
• Distance-Vector Routing
• DV Routing Features
• Bellman-Ford Algorithm
Link-State Routing
89

LIMITATION OF DISTANCE VECTOR
PROTOCOL
Demerit
1. Slow covergence
2. Counting to infinity problrm
3. Lack of variety of metrics
4. No possibility of hierarchical routing
5. Bad performance in large network
90

LINK-STATE ROUTING PROTOCOL
Concept or Idea
1. Each node monitors neighbours/local links and
advertise them to the network.
2. Each node maintains : full graph
3. Each node responsible for learning/monitoring its
neighbours and their names.
4. Each router stores: most recently generated LSP
from other nodes.
5. Each router uses complete information on the
complete topology.
91

Characteristics
1. Maintains centralised database of whole network.
2. Calculation and routing are still distributed.
3. Exchange info only when there is change.
4. Each router maintains identical database.
5. Quick convergence
92

Limitation
1. More memory required
2. Complex procedure
93

DV-ROUTING VS LS-ROUTING
• Comaprison
Feature DV-Routing LS-Routing
Bandwidth Less More
Knowledge Local Knowledge Global Knowledge
Algorithm Bellman-Ford Algorithm Dijkstra Algorithm
Traffic Less More
Converges Slower Faster
Problem Count to infinity and
looping persist
No problem
Types RIP,IGRP OSPF,IS-IS
94

SUMMARY
Lecture-8 : Link-State Routing
Q.1 What is Link-state routing protocol?
Q.2 What are the limitations of distance-vector routing
protocol?
Q.3 What are the features of distance-routing
protocol?
Q.4 What is the basic idea behind link-state routing
protocol?
Q.5 What are the limitation of link-state routing
protocol?
95

ACTIVITY
Lecture-8 : Link-State Routing
video :
Routing types
https://www.youtube.com/watch?v=C3trPo6qVv4
96

CONGESTION
&
CONGESTION
CONTROL
• Problem and Solution
97

LECTURE – 9
Objectives
Congestion
Cause of Congestion
Effect of Congestion
Congestion Control
Recap
• Limitation of DV Routing
• Link-State Routing
• LS Routing Features & limitations
• Shortest path first Algorithm
Congestion & Congestion Control
98

WHAT IS CONGESTION?
Problem
1. A state occurring in network layer when the
message traffic is so heavy that it slows down
network response time.
2. Network congestion in data networking and
queuing theory is the reduced quality of service
that occurs when a network node or link is carrying
more data than it can handle.
99

CONGESTION IN NETWORK
• Example
100

CAUSES OF CONGESTION
Reason
1. No Buffer space.
2. Mismatch in Processing speed leading to data loss.
3. Slow transmission link and over load in
transmission link than it can handle (Transmission
link capacity = speed and load that it carry data) .
101

EFFECTS OF CONGESTION
Impact -1
1. As offered load in network increases delay also
increases.
2. No matter what technique is used for
congestion control, the delay grows without
bound as the load approaches the capacity of
the system.
102

EFFECTS OF CONGESTION
Impact -2
1. As response time decreases , performance also
decreases.
2. The two vital parameters of the network
performance, namely throughput and delay.
3. The throughput can be defined as the percentage
of utilization of the network capacity.
4. If delay increases, retransmission occurs, making
situation worse.
103

CONGESTION CONTROL
Solution
1. Refers to techniques and mechanisms that can
either prevent congestion, before it happens, or
remove congestion, after it has happened.
2. Congestion control mechanisms are divided into
two categories,
• Prevents the congestion from happening.
• Removes congestion after it has taken place.
104

SUMMARY
Lecture-9: Congestion & Congestion
Control
Q.1 What is congestion?
Q.2 What are the causes of congestion?
Q.3 What is the impact on network after congestion?
Q.4 What is congestion control?
Q.5 What are the types of congestion control?
105

ACTIVITY
Lecture-9: Congestion & Congestion
Control
Reading:
• How the performance of congestion control carried
out?
106

CONGESTION
CONTROL
• Network Layer Functionality
107

LECTURE – 10
Objectives
Congestion control Taxonomy
Open Loop congestion control
methods
Closed Loop congestion control
methods
Recap
• Congestion
• Cause of Congestion
• Effect of Congestion
• Congestion Control
Congestion Control
108

CONGESTION CONTROL SCHEMES
• Type-1 Congestion control scheme
Destination control
Source control Implicit Feedback Explicit feedback
Persistent
Local
Responsive
Global
Open Loop control Closed loop control
109

CONGESTION CONTROL
TAXONOMY
• Type-2
110

CONGESTION CONTROL METHODS
2 types
Open loop :
1. In this method, policies are used to prevent the
congestion before it happens.
2. Congestion control is handled either by the source
or by the destination.
Closed loop:
1. Closed loop congestion control mechanisms try to
remove the congestion after it happens.
111

OPEN LOOP CONGESTION
METHODS
Slide- 1
• Retransmission Policy:
It is the policy in which retransmission of the packets
are taken care.
• Window Policy:
The type of window at the sender side may also
affect the congestion.
• Acknowledgment Policy:
The acknowledgment policy imposed by the receiver
may also affect congestion.
112

OPEN LOOP CONGESTION
METHODS
Slide- 2
• Discarding Policy:
A good discarding policy by the routers may prevent
congestion and at the same time may not harm the
integrity of the transmission
• Admission Policy:
An admission policy, which is a quality-of-service
mechanism, can also prevent congestion in virtual-
circuit networks.
113

CLOSED LOOP CONGESTION
METHODS
Slide-1
• Backpressure
114

METHODS
Slide-2
• Choke Packet
115

METHODS
Slide- 3
• Implicit Signaling :In implicit signaling, there is no
communication between the congested node or
nodes and the source.
• Explicit Signaling :The node that experiences
congestion can explicitly send a signal to the source
or destination.
- Types : Backward Signaling , Forward Signaling
116

SUMMARY
Lecture-10 : Congestion Control
Q.1 What are the two variations of congestion control
taxonomy?
Q.2 What is open loop congestion control?
Q.3 What is closed loop congestion control?
Q.4 What are the methods used under open loop
congestion control ?
Q.5 What are the methods used under closed loop
congestion control?
117

ACTIVITY
Lecture-10 : Congestion Control
Exercise:
• Categorize the prevention and removal congestion
methods in network layer.
118

QUALITY OF
SERVICE
• Data traffic Management
119

LECTURE – 11
Objectives
Quality of Service
Traffic descriptor
Traffic profile
QoS Techniques
Recap
• Congestion control Taxonomy
• Open Loop congestion control methods
• Closed Loop congestion control methods
Quality of Service
120

QUALTY OF SERVICE
Concept
1. Description or measurement of over all
performance of service.
2. Refers to traffic control mechanism.
3. Purpose :
• Ex: Time-criticial applications , video and audio
conferencing / streaming : requires bounded delay
and loss rate
121

QOS REQUIRMENTS
Flow Characteristics
1. Delay
2. Delay Variation(Jitter)
3. Throughput
4. Error Rate
122

TRAFFIC DESCRIPTOR
• Qualitative values that represent a data flow
123

TRAFFIC PROFILE
• 3 types
124

QOS TECHNIQUES
4 types
1. Scheduling : queueing in fair manner .
2. Traffic shaping : mechanism to control the amount
and rate of traffic.
3. Resource reservation: resources for flow of data are
reserved.
4. Admission Control : mechanism implemented by
routers or switch
125

TRAFFIC SHAPING ALGORITHM
QoS
Traffic Shaping:
1. It is about regulating average rate of dataflow.
2. It is a method of congestion control by providing
shape to data flow before entering the packet into
the network.
3. At connection set-up time, the sender and carrier
negotiate a traffic pattern ( shape).
126

TRAFIIC SHAPING METHODS
2 types
1. Leaky-Bucket Algorithm
2. Token-Bucket Algorithm
127

SUMMARY
Lecture-11 : Quality of Service
Q.1 What is QoS in computer network?
Q.2 What are the techniques involved in QoS?
Q.3 What is traffic shaping ?
128

ACTIVITY
Lecture-11: Quality of Service
Reading:
Introduction to Quality of service
https://networklessons.com/cisco/ccna-routing-
switching-icnd2-200-105/introduction-qos-quality-
service
129

TRAFFIC
SHAPING
METHODS
• Data Traffic Management
130

LECTURE – 12
Objectives
Traffic shaping Methods
• Leaky –Bucket Algorithm
• Token-Bucket Algorithm
Recap
• Quality of Service
• Traffic descriptor
• Traffic profile
• QoS Techniques
Traffic Shaping Methods
131

WHAT IS LEAKY-BUCKET?
Traffic shaping
1. It is a traffic shaping mechanism that controls the
amount and the rate of the traffic sent to the
network.
2. A leaky bucket algorithm shapes busty traffic into
fixed rate traffic by averaging the data rate.
3. The rate at which the water is poured into the
bucket is not fixed and can vary but it leaks from
the bucket at a constant rate.
132

LEAKY-BUCKET ALGORITHM
Steps
The leaky Bucket used to control rate of flow of data
packets.
1. It is implemented as a single –server queue with
constant service time.
2. If the bucket ( buffer) overflows then packets are
discarded.
3. In this algorithm the input rate can vary but the o/p
rate remains constant .
4. This algorithm saves busty traffic. 134

WHAT IS TOKEN-BUCKET ?
Concept
1. The leaky bucket algorithm allows only an average
(constant) rate of data flow. Its major problem is
that it cannot deal with bursty data.
2. A leaky bucket algorithm does not consider the idle
time of the host.
3. To over come these issues token- Bucket concept
introduced where bucket contain tokens instead of
packets
135

LEAKY BUCKET VS TOKEN BUCKET
• Comparison
TOKEN - BUCKET LEAKY-BUCKET
Token dependent Token are independent or NO tokens.
Packets can only transmitted when there
are enough token.
If bucket is full packet or data is
discarded.
It allows large bursts to be sent@ faster
rate after that constant rate.
Packets are transmitted continuously.
If bucket is full token are discarded, but
not the packet.
It sends the packet @ constant rate
It saves token to send large bursts. Does not save token.
137

TOKEN-BUCKET ALGORITHM
Steps
1. The token Bucket Algorithm compare to leaky
bucket algorithm allow the output rate vary
depending on the size of burst.
2. In this algorithm the buckets holds token to
transmit a packet, the host must capture and
destroy or fetch one token.
3. Tokens are generated by a clock at the rate of on
token every @T sec
4. Idle hosts can capture and save up tokens ( up to
max size of the bucket) in order to send larger
bursts later.
138

SUMMARY
Lecture-12 : Traffic Shaping Methods
Q.1 What is leaky-bucket ?
Q.2 Explain leaky-bucket algorithm.
Q.3 What is Token-Bucket ?
Q.4 Explain token-bucket algorithm.
Q.5 Differences between leaky-bucket and token
bucket .
139

ACTIVITY
Lecture-12: Traffic Shaping Methods
Exercise problems and solution:
Leaky bucket Algorithm
http://site.iugaza.edu.ps/olatif/files/2010/03/Leaky-
Bucket-Additional-Problems-with-Solutions.pdf
140

INTERNET
PROTOCOL-
IPV4
• Concept & Format
141

LECTURE -13
Objectives
IPV4 concept
IPV4 header format & description
IPV4 Address
Subnet
CIDR
Recap
• Traffic shaping Methods
• Leaky –Bucket Algorithm
• Token-Bucket Algorithm
Internet Protocol-IPV4
142

INTERNET PROTOCOL VERSION 4
IPV4- Concept
1. IPv4 was the first version deployed for production
in the ARPANET in 1983.
2. Internet layer protocol of the TCP/IP model.
3. Dotted-decimal format : 4 numbers
4. 32 bit address
5. Composed: Network part + Host part
143

IPV4 HEADER
• Datagram format
144

FORMAT DESCRIPTION
Description-1
• Version: The IPv4 has the version number 4.
• Header length: It shows the size of the header.
• DSCP: type of service included.
• Total length: It denotes the size of the header plus
the size of the data packet.
• Identification: 3 fields used with IP fragmentation.
145

FORMAT DESCRIPTION
Description-2
• Flags: It is used to denote the fragmentation
procedure.
• Fragment offset: It indicates the fragment number
and source host.
• Time to leave: ensure that packet don't circulate
forever.
• Protocol: It denotes the protocol that it is using for
transmitting data.
146

FORMAT DESCRIPTION
Description-3
• Header Checksum: This field is used for error
detection.
• Source IP address: It saves the IP address of the
source end host. The length is 32-bit.
• Destination IP address: It saves the IP address of
the destination host. The length is 32-bit.
147

IPV4 ADDRESS
Concept
1. A number which identifies a device on a network.
2. Functions: identification of host and route .
3. The term subnet mask is only used within IPv4.
4. Uses both class and classless inter-domain (CIDR)
routing concept and notation.
5. Class address : range from 0- 255.
148

CIDR
Concept
1. Method for allocating IP addresses and IP routing.
2. The IETF introduced CIDR in 1993.
3. It is based on variable-length subnet
masking (VLSM).
4. Process of allocating address blocks to
organizations based on their actual and short-term
projected needs.
5. Format : x.y.z.t/n where x.y.z.t defines one address
and /n defines the mask.
149

IPV4
Example
Ex 1: Class address : Class A
• 127.255.255.255
Ex 2: CIDR address
• 192.0.2.0/24
150

SUBNET & SUPERNET
Concept
1. Dividing the large block in class A or B into several
group of smaller networks => Subnet
2. Merging the smaller block in class C into larger or
super network => Supernet
151

SUMMARY
Lecture-13 : Internet Protocol-IPV4
Q.1 What is IPv4?
Q.2 What is IPv4 header format?
Q.3 What is IPv4 class address?
Q.4 What is IPV4 CIDR address?
Q.5 What is subnet and super net?
152

ACTIVITY
Lecture-13: Internet Protocol-IPV4
Reading:
• History of IP protocol.
153

IPV4 CLASSFUL
ADDRESS
• Class types
154

LECTURE – 14
Objectives
Classful Address
Classful address range
Binary and decimal range
Conversion from decimal to binary
Conversion from binary to decimal
Recap
• IPV4 concept
• IPV4 header format & description
• IPV4 Address
• Subnet
• CIDR
IPV4 Classful Address
155

CLASSFUL ADDRESSING
• Size and Casting
Class Size Casting
163

CLASS ADDRESS RANGE
• Network scale
Class
164

ADDRESSING RANGE
• Decimal and Binary format
Decimal
165

COVERSION DECIMAL TO BINARY
IPV4
Given Decimal :
192.168.158.0
Solution in Binary format :
11000000.10101000.10011110.00000000
166

COVERSION BINARY TO DECIMAL
• IPV4
2^7
=128+64.128+32+8.128+16+8+4+2.0
=192.168.158.0
167

SUMMARY
Lecture-14 : IPV4 Classful Address
Q.1 What is range of IPV4 classful address in binary?
Q.2 What is the range of IPV4 classful address in
decimal?
Q.3 What is general size and type of casting of classful
address?
Q.4 How to convert IPV4 classful binary address to
decimal?
Q.5 How to convert IPV4 classful decimal address to
binary?
168

ACTIVITY
Lecture-14: IPV4 Classful Address
Evaluate:
• How to find min and max range of IPV4 classful
address?
169

INTERNET
PROTOCOL-
IPV6
• Currently used
170

LECTURE – 15
Objectives
Internet Protocol V6
IPV6 Address structure
IPV6 header Format
Comparison between IPV4 & IPV6
Recap
• Classful Address
• Classful address range
• Binary and decimal range
• Conversion from decimal to binary
• Conversion from binary to decimal
Internet Protocol-IPV6
171

INTERNET PROTOCOL V6
Recent version
1. Communication Protocol
2. Moto: provide Larger addressing space.
3. Function: Indentication, Location system & Routes.
4. IPv6 uses a 128-bit address.
5. IPv6 addresses are represented as eight groups,
separated by colons, of four hexadecimal digits.
6. Format: group1:group2: ……etc…. :group8
172

Address parts
1. Network component - 64 bits
2. Node component – 64 bits
-----------------------------------------
Totals – 128 Bits
173

• Example
174

NETWORK COMPONENT
• IPV6
175

IPV6 HEADER
• Datagram Format
176

FORMAT DESCRIPTION
Description -1
• Version: It is of 4 bits and contains the version of IP which is 6.
• Priority: 4 bits describes priority of the packet w.r.t traffic
congestion.
• Flow label: 24 bits (3-byte) is designed to provide special
handling for flow of data.
• Payload length: 16 bits (2-byte) payload length field defines
the length of the IP datagram. Excluding the base header.
177

FORMAT DESCRIPTION
Description - 2
• Next header: 8 bits field defining the header that follows the
base header in the datagram.
• Hop limit: 8-bit hop limit field serves the same purpose as the
TTL field in IPv4.
• Source address: 128-bits ( 16-byte) and denotes internet
address of original source host of the datagram.
• Destination address: It is also of 128 bits and denotes the
internet address of final destination of the datagram.
178

IPV4 VS IPV6
• Key Comparison
Feature
179

SUMMARY
Lecture-15 : Internet Protocol-IPV6
Q.1 What is IPV6?
Q.2 What are the components of IPV6?
Q.3 What is the format of IPv6?
Q.4 What is the IPV6 header format?
Q.5 Comparison between IPV4 and IPV6
180

ACTIVITY
Lecture-15: Internet Protocol-IPV6
Reading :
Types of IPV6 Addressing
http://www.steves-internet-guide.com/ipv6-guide/
181

IP
SUPPORTING
PROTOCOLS
• NAT,ARP,ICMP,DHCP
182

LECTURE – 16
Objectives
Network Address Protocol
Network Address Translation
Internet control message protocol
Dynamic Host configuration
Recap
• Internet Protocol V6
• IPV6 Address structure
• IPV6 header Format
• Comparison between IPV4 & IPV6
IP supporting Protocols
183

NETWORK ADDRESS
TRANSLATION
Concept
1. Service used in routers.
2. Over come IPV4 address shortage.
3. Method/process of remapping local IP address to
Global IP address and vice versa
4. Translating public IP address to private IP address
and vice versa
184

NETWORK ADDRESS
TRANSLATION
• Example
185

ADDRESS RESOLUTION
PROTOCOL
Concept
1. Function: to translate Logical address to physical
address.
2. Mapping: IP address to MAC address
3. Layer 2 protocol
186

ADDRESS RESOLUTION
PROTOCOL
• Example
187

WHY ICMP?
Concept
IP Limitation:
1.Error reporting or correcting mechanism.
2.No management of queries
188

IP SUPPORTING PROTCOLS
• Network layer protocols
ICMP,IGMP
IP
ARP,RA
RP
189

INTERNET CONTROL MESSAGE
PROTOCOL
Concept
1. It is a network layer protocol
2. It reports errors and provides information related to
IP packet processing.
3. Error example : that a requested service is not
available or that a host isn’t reachable.
4. Tool : ping or traceout
190

INTERNET CONTROL MESSAGE
PROTOCOL
• Example
191

DYNAMIC HOST CONFIGURATION
PROTOCOL
Concept
1. Application layer protocol.
2. Over the issues of manual IP configuration.
3. It allows the host to obtain an IP address
automatically.
4. Also refferred as : plug-and-play protocol.
5. Mechanism: DORA - Discover, Offer, Request, Ack
192

DYNAMIC HOST CONFIGURATION
PROTOCOL
• Example
193

SUMMARY
Lecture-16 : IP supporting Protocols
Q.1 What is NAT?
Q.2 What is public IP address & private IP address?
Q.3 What is ARP?
Q.4 What is ICMP?
Q.5 What is DHCP?
194

ACTIVITY
Lecture-16: IP supporting Protocols
Reading:
ARP
https://www.youtube.com/watch?v=zTWa2Pqlgp0
DHCP
https://www.youtube.com/watch?v=IUOVSIKj6GU
195

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