Efficient utilization of communication resources for crises management via introducing Quality of Se

1
Efficient utilization of communication resources
for crises management via introducing Quality of
Services (QoS) of network traffic

• Aleksandar Tsankov Institute for Parallel
  Processing
• Bulgarian Academy of Sciences

This work is supported by NATO Science Committee
under the project SfP 981149 NATO Advanced
Research Workshop Velingrad, October 21-25.2006
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Computer networks for crises management

• Computer networks for crises management are
  complex systems which consist of stationary and
  mobile management centers, exchanging information
  via different communication channels.
• In order to ensure the efficient work of crisis
  management staffs and rescue teams, crises
  management networks have to have ability for
  sharing its resources differentially between
  various users and applications according to prior
  defined criteria.
• That means supporting with high degree Quality of
  Services (QoS) of network traffic for different
  users and applications they use in process of
  crises management.

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Computer networks for crises management
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Hierarchycal layers of computer networks for
crises management
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Hierarchycal layers of computer networks for
crises management

• Due to the fact that in transport subsystem are
  located main part of specific functions for
  network management in many cases it is identifyed
  with term "computer network".
• In this paper are discused methods for
  enhancement of transport subsystem, so when
  computer network for crises management are
  concerned, it is mean transport subsystems of
  such networks.

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Ideal vs. real network for crises managemanet

• Ideal network
• no packet losses
• traffic delays are formed only from time for
  packet management in network equipment
• there is no jitter in delays
• network bandwidth is suficcient for all
  requirements.
• Real network
• network bandwidth is limited and is not enough
  for all applications and users at the same time
• there are delays due to the network overloads
• there are packet losses.
• Solution is to implement the Quality of Services
  (QoS) for bandwidth management

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Parameters of QoS

• Quality of Services giving the applications and
  users predictable servicing in data delivery
  (transport servicing).
• All parameters of network traffic which should be
  satisfied by QoS fall into one of following
  categories
• ability for predictable bandwidth management
• minimizing packet loss and errors
• managing traffic delays and jitter.

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Predictability of network traffic

• Two main classes of network applications
• applications which traffic is constant flow
  (stream) characterized with high level of
  predictability of generated traffic which enters
  the network with Constant Bit Rate (CBR)
• applications which traffic is bursty flow
  characterized with high degree of
  unpredictability of generated traffic which
  enters the network with Variable Bit Rate (VBR)

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Sensibility to delays and jitter

• Asynhronous applications no restrictions in
  traffic delays (elastic traffic)
• Synhronous applications sensible for packet
  delays
• Interactive applications delays could be noted,
  but not affect functionality of application
• Izohronous applications have a threshold of
  permissible delays
• High sensible applications packet delays
  disrupt functionality of the applications.

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Sensibility to packet loss

• Sensible applications practically all
  applications which send/receive symbol
  information
• Insensible applications many application which
  send/receive data for inertial physic processes
  multimedia applications

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Models for QoS management

• Computer netwrok for crises management is a
  distributed media which consists of many network
  devices. This determines the great complexity in
  imposing unified requirements fof QoS from end to
  end. For solving that problem in network the
  management of QoS is needed.
• Base architecture of QoS management includes
  elements from 3 main types
• - Resources of network node for processing the
  network traffic in accordance to required QoS
  degree
• - Protocols for QoS signalisation for
  end-to-end coordination the work of all network
  devices
• - Centralized functions for QoS policing,
  management and accounting.

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Models for QoS management
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QoS resources of network node

• Main executive mechanisms for QoS management.
  Consist of following elements
• mechanisms for queuing management vital element
  for any network equipment based on packet
  switching technology. There are numerous
  algorhytms for queuing management (FIFO, Priority
  Queuing - PQ, Weighted Fair Queuing WFQ etc.)
  
• mechanisms for traffic conditioning implemented
  in network nodes for QoS and solving the task for
  creating the needed environment for traffic
  servicing via classifying, policing and shaping.

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Prerequisites for implementing QoS in computer
networks for crises management

• great number of users distributed in different
  geografically detached centers for crises
  management
• communication channels which connect centers are
  with fixed limited bandwidth
• existance of great number of information flows
  with different requirements for parameters of
  communication channels (bandwidth, delays, packet
  loss)
• abilities for assigning priorities and rate
  limits per user basis (fine granularity/microflows
  )
• abilities for assigning priorities and rate
  limits per type of application basis (coarse
  granularity/aggregated flows).

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Existing models for QoS management

• Link-Sharing and Resource Management Models for
  Packet Networks, Sally Floyd and Van Jacobson,
  1995
• In this paper authors introduced a solution for
  QoS managemet in networks with similar
  requirements.
• Features of S. Floyd and V. Jacobson model
• could be implemented using hierarchical queuing
  classes over single network interface
• existance of various criteria for classifying,
  policing and shaping the network traffic
• each interior of leaf class should receive
  roughly its allocated link-sharing bandwidth
• if all leaf and interior classes with sufficient
  demand have received at least their allocated
  link-sharing bandwidth, the distribution of any
  excess bandwidth should not be arbitrary, but
  should follow some set of reasonable guidelines.

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Link-Sharing and Resource Management Models for
Packet Network
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Proposed solution

• Things that could be futher implemented in the
  existing method are
• abilities for imposing priorities and clear rate
  limits for traffic consumption of each user no
  matter what type of application it is generated
  on
• abilities for prioretizing and link-sharing the
  network traffic over different types of
  applications
• link-sharing between user's classes depending on
  current state of network consumption.

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Proposed solution
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Approaches for building proposed method

• 1. With two routers

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Approaches for building proposed method

• Advantages of method with two routers
• easily conforms within requirements
• clear and understandable way for implementation.
• Shortcommings of method with two routers
• needs separate network interfaces for 2 types of
  traffic management applications and users
  based
• additional network equipment is needed
• in the case of already established communication
  centers it could be impossible to add another
  network node without changing network settings.

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Approaches for building proposed method

• 2. One router with support of InterMediate
  Queuing (IMQ)
• This solution overcomes already stated
  shortcommings. It is based on following elements
• Linux-based router with support of various
  algorhytms for QoS
• modified kernel with InterMediate Queuing (IMQ)
  support
• modified iptables package with InterMediate
  Queuing (IMQ) support.

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Packet traversal in the modified Linux kernel
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Abilities of IMQ

• InterMediate Quqeuing device (IMQ) is an
  artificial network interface existing only in
  Linux kernel space. It has, however, abilities
  for attaching queuing disciplines on it just like
  a real network interface.
• This fact gives us an opportunity to implement
  the method for two stage QoS on one router.

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Network diagram of Two Stage QoS using IMQ
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Testing proposed model in different scenarious

• 1. Initial testbed for proposed model was
  Computer Aided Exercise EU TACOM SEE 2006 which
  took place in 23 24.07.2006 in IPP BAS,
  Sofia. During the exercise 40 workstations and
  servers was working and generate network traffic
  which had to be managed accroding to prior
  defined criteria.
• 2. Two class C networks with different allocated
  bandwidths and number of simultaneously working
  users.

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Computer Aided Exercise EU TACOM SEE 2006

• Setup
• Linux-based router with IMQ support
• Backbone channel with bandwidth 10 Mb/s
• 35 workstations, 5 servers, 1 DVR
• per-user rate limits of 1 Mb/s
• per-application rate limits as follows
• priority 1 class bandwidth up to 2 Mb/s
  multimedia traffic (Skype, VoIP)
• priority 2 class bandwidth up to 3 Mb/s SMTP
  traffic
• priority 3 class bandwidth up to 5 Mb/s WWW
  traffic
• priority 4 class bandwidth up to 8 Mb/s other
  traffic.

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First class C network

• Setup
• Linux-based router with IMQ support
• Backbone channel with bandwidth 2.5 Mb/s
• 230 workstations, 3 servers
• per-user rate limits as follow
• priority 1 class bandwidth up to 512 Kb/s
• priority 2 class bandwidth up to 380 Kb/s
• priority 3 class bandwidth up to 256 Kb/s
• priority 4 class bandwidth up to 128 Kb/s.
• per-application rate limits as follows
• priority 1 class bandwidth up to 380 Kb/s
  multimedia traffic (Skype, VoIP), interactive
  sessions (SSH, Telnet)
• priority 2 class bandwidth up to 1 Mb/s WWW,
  SMTP, POP3 traffic
• priority 3 class bandwidth up to 1.5 Mb/s
  other traffic
• priority 4 class bandwidth up to 2.5 Mb/s
  massive downloads traffic.

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Second class C network

• Setup
• Linux-based router with IMQ support
• Backbone channel with bandwidth 1 Mb/s
• 150 workstations, 3 servers
• per-user rate limits as follow
• priority 1 class bandwidth up to 512 Kb/s
• priority 2 class bandwidth up to 380 Kb/s
• priority 3 class bandwidth up to 256 Kb/s
• priority 4 class bandwidth up to 128 Kb/s.
• per-application rate limits as follows
• priority 1 class bandwidth up to 256 Kb/s
  multimedia traffic (Skype, VoIP), interactive
  sessions (SSH, Telnet)
• priority 2 class bandwidth up to 512 Kb/s
  WWW, SMTP, POP3 traffic
• priority 3 class bandwidth up to 512 Kb/s
  other traffic
• priority 4 class bandwidth up to 1 Mb/s
  massive downloads traffic.

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Evaluation of the results from three scenarious

• Scenario 1 CAX EU TACOM SEE Due to the fact
  that bandwidth of backbone channel (10 Mb/s) is
  sufficient for all types of applications and user
  requirements, it can be stated that tested
  network is close to ideal network (there are no
  packet losses, delays and limiting one type of
  traffic in favour of other). In this situation
  mechanisms for traffic prioretizing are not
  turned on.

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Computer Aided Exercise EU TACOM SEE 2006 -
results
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Computer Aided Exercise EU TACOM SEE 2006 -
results
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Evaluation of the results from three scenarious

• Scenario2 First class C network Analyzing the
  graphics of traffic distribution it it obvious
  that there are periods of congestion in the
  network but they are very short and could be
  neglected. It can be stated that conditions in
  this network are optimal.

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First class C network distribution of
applications traffic
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Evaluation of the results from three scenarious

• Scenario3 Second class C network Analyzing the
  graphics of traffic distribution it it obvious
  that there are prolonged periods of traffic
  congestion. In these situations mechanisms for
  traffic prioretizing are turned on and traffic
  from high priority classes are favoured at the
  expense of others. On the slide with traffic
  delays was shown that there are significant
  traffic delays for traffic of lowest priority
  class in the periods of congestion.

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Second class C network distribution of
applications traffic
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Traffic delays for different classes of
applications
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Conclusions

• The best conditions for network users are in
  situation where computer network is close to
  ideal. Such conditions, however, are rare
  that's why regulation of network traffic is a
  must.
• Results from the study show that proposed method
  for two stage management of network traffic is an
  effective solution of the formulated problems.
• A further goal that could be done is a thorough
  research of interactions between two stages of
  network management and formulation of
  dependencies which will allow effective
  reconfiguration of network parameters in cases of
  arising the changes in network environment.