Multicast%20Admission%20Control%20in%20DiffServ%20Networks

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Multicast Admission Control in DiffServ Networks

• Department of Mathematical Information Technology
• University of Jyväskylä
• Finland

2
Introduction

• IPTV, video conferences, etc. are more and more
  transferred in the IP networks nowadays than
  earlier
• Video services demand strict QoS limits in terms
  of delay, jitter and packet loss
• Multicast is a relevant transmission mechanism
  for these services
• Differentiated Services is likely to be the most
  used QoS architecture in future

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The Methods

• There are three different admission control
  methods Measurement based 12 and Parameter
  based
• The methods are distributed to the edge nodes
• Based on filtering the join requests from
  customers
• The admission control methods are divided into
  three distinct phases

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Phase 1 Edge test

• Is common for all the methods
• If the edge router that receives the join request
  already is forwarding the particular group, the
  join is automatically accepted
• Otherwise, the method moves to the phase 2 before
  making any decisions

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Phase 2 Bandwidth test (1/2)

• Measurement based methods 1 2
• Measurement 1 inspects if there is enough room on
  the links for the new receiver
• Measurement 2, on the other hand, inspects if
  there is room within the class on every link
• Based on MGRIP protocol
• Checks only the path between egress edge node and
  branching node
• Only the links whose utilization would increase
  are inspected

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Phase 2 Bandwidth test (2/2)

• Parameter based method
• The available bandwidth is aproximated using the
  following equation
• Other assumptions are the same than with
  measurement based methods 1 2

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Phase 3 Measurement test (1/2)

• Methods Measurement 1 and 2
• Egress edge joins the group, receives n first
  packets and calculates loss, delay and jitter for
  the packets
• Exponential average of current and history
  results is used to compare against defined limits
• Uses packets RTP headers to calculate QoS
  parameters

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Phase 3 Measurement test (2/2)

• Parameter based method
• The maximum end-to-end delay, that can occur on
  the path, is approximated using the following
  equation
• In our simulation environment, every node tracks
  the number of active connections it is forwarding

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Simulations

• Simulations were done with Network Simulator 2
• Traffic of two customers was measured and other
  customers produced the background traffic
• FTP, IPTV and video conference were used as the
  applications
• Video traffic was produced from real captured
  video stream

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Simulation topology
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Results

• Tens of identical simulations with different
  background traffic loads were ran
• First case shows a situation in a slightly loaded
  network
• Second case shows a situation with more loaded
  network
• The last case presents the influence of backgroud
  traffic

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Results

• Low utilization Throughput

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Results

• High utilization Delay

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Results

• High utilization Loss

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Results

• High utilization Throughput

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Results

• Background traffics effect on throughput

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Results

• Background traffics effect on delay

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Results

• Background traffics effect on loss

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Conclusions based on simulations

• The need for admission control can be seen
  clearly
• Our simple admission control method gives better
  quality for the customers being served
• Decreased throughput and rejection of some of the
  requests is the cost of the method

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ADC implementation

• Linux workstation with more than 1 NIC as a Edge
  router
• XORP is an open source IP router platform which
  is used to perform the router functionality
• Unix IPtables is used to filter the packets
  needed for admission control decisions and
  measuring purposes
• ADC implementation performs packet loss, jitter
  and delay calculations which it uses for decision
  making
• Next, a multicast receiver implementations will
  be done to easily measure the quality of service
  experienced by the receivers

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ADC network topology
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• The end