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INTERNET
TRAFFIC
MANAGEMENT
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What is a Computer Network?
A computer network is a data communications
system which interconnects computer systems at
various different sites. A network may be
composed of any combination of LANs, orWANs.
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What is Network Traffic?
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Density of data present in the network.
Communication devices access resources and also
get requests to carry out some work.
So a lot of request, response and control data.
Load on the network.
Other devices may get delayed in theirrequirements.
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Why to worry about traffic?
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Widely used network
Different types of network
Service Quality
Dynamic nature of traffic
Complex nature of traffic data
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Traffic Management
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Controlling network traffic requires limiting
bandwidth to certain applications, guaranteeing
minimum bandwidth to others, and marking trafficwith high or low priorities. This exercise is called
traffic management.
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General Process of Traffic
Management
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Traffic Measurement
Traffic Analysis
Management Techniques
Result Evaluation
Final Result
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Organizational Requirements for
managing Network Traffic?
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To guarantee maximum bandwidth to mission critical
applications.
To block music or video downloads.
To block music file sharing and avoid copyright
infringement liability.
To delay investments in additional network capacity.
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Reasons for Motivation of
measurement
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Making sure things keep working
More capacity need
Billing data
Understanding to improve network
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Performance Metrics
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Basic performance metrics :
Packet loss
Delay
Throughput
Availability
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Where should we manage
traffic?Usually deployed at the WAN edge of an enterprise site.
The LAN-WAN juncture is also where both Internet and
Intranet traffic enters and exits the enterprise.
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Traffic
Management
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Approaches for Traffic Measurement
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1.Server Logs:
Web servers configured to record information about
all client requests.
Egmost servers have a log file access whererequests and responses are saved.
Each line of the access log contains information on a
single request for a document.
An example is:
cs.fudan.edu.cn[15/Aug/1999:14:50:05 - 0600]
"GET/HTTP/1.1" 200 1200
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Approaches for Traffic Measurement
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2. Passive Measurement:
Choose an appropriate site and passively capture
every IP packet through it.
Ideal site would be one through which manyconnections pass.
Eg a major gateway site.
Many monitoring platforms. One such platform isTCPDump based WinDump.
Users can build complicated Boolean expressions to
decide which data packets to catch.
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Approaches for Traffic Measurement
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3. Active Measurement:
Users or providers are directly related to the activities
of measurement in the following ways:
Injection of probes into network by users and
providers Ping and Trace route
Path connectivity
Round-trip delay
User-application performance as seen from hosts Loss
Delay
Throughput
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Differentiated Service Architecture
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Differentiated Services or DiffServ is a computer
networking architecture that specifies a
simple, scalable and coarse-grained mechanism for
classifying and managing network traffic and providingQuality of Service (QoS) on modern IP networks.
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Differentiated Service Architecture
Two different service types: implementation and
problems
Two-bit differentiated services architecture Problems with end-end bandwidth allocation based
on level of marked traffic
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Contd.
Why do we need differentiated services?
Different users
Different applications Service allocation
For example, one goal of assured service is to
allocate the bandwidth of the Internet todifferent users in a controlled way during
periods of congestion
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How to describe a service What is provided to the customer
E.g., 1 Mbps, continuously available
To where is this service provided
A single destination
A group
All nodes on local provider
Everywhere
Level of assurance provided to service
What level of performance uncertainty can user
tolerate
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Two distinct service types
Assured service
Premium service
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Assured service
Provide different levels of best-effort service at
times of network congestion
Expected capacity
In packets unlikely to be dropped
Out packets - no assurance
Queuing
Best effort
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Mechanism for assured service
Host
First-hop
Out- and in-dropper
RIO scheme, packetsare treated preferentially
Marking packetsaccording to the service profile
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Premium service
Fundamentally different Internet best effort
service - high priority traffic has its own queue in
routers
Shaped, hard-limited to provisioned peak rate
No bursts are injected into net
Virtual wire, available whenever needed
Regular flow pattern, no queuing Shared, with best-effort
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Mechanism for premium service
Host First-hop
Intra-network
Router
H-Q: premium, no droppingL-Q: best effort, dropping on
congestion
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Two-bit differentiated services
architecture Forwarding path mechanisms
Leaf routers
Input interface: a traffic profile
Output interface: two queues (HQ, LQ)
Border routers
A Profile Meter at the input interface
T ffi fl f d h t t
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Traffic flow from end-host to
ISP
Host
First-hop Router
Internal Router
Border Router
Border Router
ISP
Company A
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Block diagram of leaf router input
functionality
PacketClassifier
ClearA&P
bits
ForwardingEngine
Marker N
Marker 1
rriving packet
Best Effort
Flow1
Flow N
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Markers to implement the two
different services
Wait for
token
Test if token Set A bit
SetP bit
PacketInput
PacketInput
Y
N
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Border router input interface
Profile Meters
Is packetmarked ?
Tokenavailable ?
Clear A bit
TokenAvailable
DropPacket
ForwardingEngine
N
N
Y
Y
P set
A set
Not marked
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Passing configuration information
Request to the leaf router
Average rate, burst, service type (P or A)
Ways of passing the message
RSVP, SNMP, network administrator
Authenticating the sender
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Architectural framework for
marked traffic allocation Pre-configuring of usage profiles is practical
Paying for level of service that is always
available Allocation follows organizational hierarchies
Each organization must be responsible for its
DM
Only bilateral agreements work
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Examples
A statically configured example with no BB
message exchanged
A statically configured example with BB
messages exchanged Dynamic allocation and additional mechanism
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