Scalable Architecture for Providing Per-flow Bandwidth Guarantees

1
Scalable Architecture for Providing Per-flow
Bandwidth Guarantees

• Dr. Vasil Hnatyshin
• Computer Science Department
• Rowan University

2
Outline

• Quality of Service (QoS), What is it?
• Providing QoS in the Internet.
• Integrated Services
• Differentiated Service
• Bandwidth Distribution Scheme (BDS)
• BDS Research Projects
• Influence of BDS on TCP traffic
• Fair bandwidth distribution using BDS
• BDS for DiffServ provisioning
• BDS for inter-domain traffic
• BDS for mobile environment

3
Introduction to QoS

• QoS, What is it?
• QoS is a quality of service received by an
  application (e.g. perceived by a user of an
  application).
• Why do we care?
• Internet supports only best-effort service
• Emerging and existing applications are often
  time-sensitive, delay-sensitive, jitter-sensitive
  or have other importance requirements which are
  not supported by best-effort Internet

4
Outline

• Quality of Service (QoS), What is it?
• Providing QoS in the Internet.
• Integrated Services
• Differentiated Service
• Bandwidth Distribution Scheme (BDS)
• BDS Research Projects
• Influence of BDS on TCP traffic
• Fair bandwidth distribution using BDS
• BDS for DiffServ provisioning
• BDS for inter-domain traffic
• BDS for mobile environment

5
Integrated Services

• Simplified Idea for each newly admitted flow
  reserve network resources at each node on the
  flows path from source to destination.
• Uses per-flow resource reservation protocol
  called resource reservation protocol (RSVP).

6
IntServ Example
7
Summary Integrated Services

• Advantages
• Capable of supporting service requirements of
  individual flows.
• Supports variety of services.
• Disadvantages
• Does not scale well to large networks.
• Potential waste of resources

8
Differentiated Services

• Goal Provide scalable QoS.
• DiffServ Implementation
• Establishes a few classes/aggregates
• Classifies arriving traffic into one of
  pre-defined classes.
• Packets are differentiated based on the DSCP
  marking set in the IP header.
• Core routers treat arriving traffic based on the
  packets class.

9
Network Architecture
10
DiffServ Scalability

• Edge Routers
• Maintain all per-flow information via SLA
• Perform traffic classification
• Mark arriving packets

Network Domain

• Core Routers
• Maintain only class information
• Treat arriving traffic based on the DSCP marking

11
DiffServ Example
12
DiffServ vs. IntServ

• Integrated Services Model
• Supports per-flow QoS
• Not Scalable
• Potential Waste of Resources
• Differentiated Services Architecture
• Scalable
• Provides only per-aggregate QoS
• Static per-class resource allocation which may
  lead to violation of user requirements

13
Outline

• Quality of Service (QoS), What is it?
• Providing QoS in the Internet.
• Integrated Services
• Differentiated Service
• Bandwidth Distribution Scheme (BDS)
• BDS Research Projects
• Influence of BDS on TCP traffic
• Fair bandwidth distribution using BDS
• BDS for DiffServ provisioning
• BDS for inter-domain traffic
• BDS for mobile environment

14
Goals of the BDS Architecture

• Scalable
• Per-flow QoS
• Fairness
• Congestion Control
• No service violation
• Dynamic Resource Allocation

15
The BDS Architecture

• Scalable
• Per-flow QoS
• Fairness
• Congestion Control
• No service violation
• Dynamic Resource Allocation

16
Network Architecture
Network Domain
The Internet
17
Flow Requirements

• Flow Specification
• Requested Bandwidth Range (RBR)
• Min Rate, Max Rate
• Aggregate bottleneck RBR
• Aggregate RBR on interface k

18
Flow Requirements

• Aggregate bottleneck RBR vs. Aggregate RBR on
  interface

Aggr. RBR on Core 2 Edge 4 5, 20 BDS
Capacity 18 Aggr. bottleneck RBR 3, 12 BDS
Bottleneck Capacity 18 Rate(Flow 2)
Aggr. RBR on Core 1 Core 3 6, 24 BDS
Capacity 18 Aggr. bottleneck RBR 6, 24 BDS
Bottleneck Capacity 18
19
Definition of Fairness

• Bottleneck Capacity
• Proportional Fairness
• Maximizing Utility Fairness

20
Admission Control

• Admission control test

21
Resource Allocation

The value of Bottleneck Capacity is not readily
available in the network, instead we use the
value of available capacity on the link as
follows
To avoid resource underutilization, we employ a
water-filling technique increase allocated
rates of individual flows as long as the
bottleneck link is not fully utilized.
22
Resource Allocation

Aggr. RBR on Core 2 Edge 4 5, 20 BDS
Capacity 18 Rate(Flow 3) 18 3 / 5
10.8 Link Utilization (10.8 6)/18
93.3 Aggr. bottleneck RBR 3, 12 BDS
Bottleneck Capacity 12 Rate(Flow 3) 12 3/3
12 Link Utilization (12 6)/18 100
Aggr. RBR on Core 1 Core 3 6, 24 BDS
Capacity 18 Rate (Flow 1) 18 (4/6) 12
Rate (Flow 2) 18 (2/6) 6 Link Utilization
(12 6)/18 100 Aggr. bottleneck RBR 6,
24 BDS Bottleneck Capacity 18 Rate (Flow 1)
18 (4/6) 12 Rate (Flow 2) 18 (2/6)
6 Link Utilization (12 6)/18 100
23
The RBR Distribution and Feedback (RDF) Protocol

• Purpose
• Distribute the Aggregate RBR among the nodes in
  the network.
• Path Probing Phase
• Edge routers periodically probe the network to
  discover the route changes (e.g. aggregate RBR,
  excess bandwidth).
• Update Phase
• Edge nodes notify the core routers about the
  change of the aggregate RBR due to flow
  activation or termination.
• Notification Phase
• Core routers notify the edge nodes about
  congestion.

24
RDF Protocol
Network Domain
25
The RDF Protocol Example
1. Initiates the Path Probing Phase
2. Updates Local Data Structures
3. Performs Admission Control Test
4. Computes Allocated Rate of F2
5. Initiates the RBR Update Phase
1. C1 initiates the Notification Phase.
6. Allows F2 to enter the network
2. Edge 1 and Edge 2 adjust allocated rates of F1
and F2 to eliminate congestion.
26
List of BDS Publications

1. V. Hnatyshin and A.S. Sethi,  "Estimation Based
   Load Distribution in the Internet," accepted for
   publication The International Journal of Computer
   and Telecommunications Networking Computer
   Networks and ISDN Systems (Elsevier).
2. V. Hnatyshin and A.S. Sethi, Scalable
   Architecture for Providing Per-flow Bandwidth
   Guarantees, Proc. of CIIT 04, St. Thomas, VI,
   November 2004.
3. V. Hnatyshin and A.S. Sethi, "Optimization of the
   Bandwidth Distribution Scheme for Handling
   Topology Changes," Proc. IPCCC'04, Phoenix, AZ,
   April 2004.
4. V. Hnatyshin and A.S. Sethi,  "Reducing load
   distribution overhead with message aggregation,"
   Proc. IPCCC'03, Phoenix, AZ, April 2003.
5. V. Hnatyshin and A.S. Sethi, Fair and Scalable
   Load Distribution in the Internet, Proc. 3rd
   International Conference on Internet Computing,
   Las Vegas, NV (June 2002).
6. V. Hnatyshin and A.S. Sethi, Achieving Fair and
   Predictable Service Differentiation Through
   Traffic Degradation Policies, Proc. SPIE QoS
   2001, Conference on Quality of Service over
   Next-Generation Data Networks, Denver, CO (Aug.
   2001).
7. V. Hnatyshin and A.S. Sethi, Avoiding Congestion
   Through Dynamic Load Control, Proc. ITCom-2001,
   SPIE's International Symposium on The Convergence
   of Information Technologies and Communications,
   Denver, CO (Aug. 2001), pp. 309-323.
8. V. Hnatyshin and A.S. Sethi,  "Bandwidth
   Distribution Scheme for Dynamic, Scalable, and
   Fair Allocation of Bandwidth," submitted for
   publication in Computer Networks journal

27
Outline

• Quality of Service (QoS), What is it?
• Providing QoS in the Internet.
• Integrated Services
• Differentiated Service
• Bandwidth Distribution Scheme (BDS)
• BDS Research Projects
• Influence of BDS on TCP traffic
• Fair bandwidth distribution using BDS
• BDS for Differentiated Services provisioning
• BDS for inter-domain traffic
• BDS for mobile environment

28
BDS Implementation

• Two students are working on implementation of BDS
  using OPNET Modeler software
• Shaun M. Mazzatenta
• Frank J. Genua

29
BDS Implementation
30
Influence of BDS on TCP traffic

• BDS and TCP Properties
• The BDS discards all out-of-profile packets (e.g.
  the packets that arrive at the rate higher than
  the rate allocated to the flow).
• TCP treats packet loss as an indication of
  severe congestion.
• Problem
• What effects, if any, does the BDS out-of-profile
  packet treatment policy (e.g. packet drop) has on
  TCP?
• Possible venues for research
• Do not drop out-of-profile packets, instead
• Shape (e.g. delay) the out-of-profile packets.
• Send an indication to TCP to slow down
  misbehaving flows.

31
Fair Distribution of Excess Bandwidth with BDS

• BDS properties
• BDS resource distribution may leave links
  underutilized.
• Excess bandwidth is distributed fairly among
  individual flows based on results of periodic
  probing.
• Problem
• How FAIR is the BDS excess bandwidth
  distribution?
• Is it Min-Max or Proportionally fair?
• Possible venues for research
• Examine fairness of the BDS excess bandwidth
  distribution through simulation.
• Create a mathematical model to prove/disprove
  fairness of the BDS excess bandwidth
  distribution.
• Modify/ Improve/ Update the excess bandwidth
  distribution of the BDS approach.

32
BDS for DiffServ provisioning

• Differentiated Services Properties
• DiffServ relies on static per-class resource
  allocation.
• Current solution uses Bandwidth Brokers (BB).
• The BB is a centralized node(s) that contains
  complete information about the network domain.
• The BB monitors traffic patterns and statically
  adjusts per-class resource allocation.
• IDEA and Venues for Research
• Examine if it is possible to use the BDS approach
  for dynamic bandwidth allocation among DiffServ
  classes based on their resource usage or resource
  requests?

33
Future BDS Extensions

• BDS Properties
• The BDS works only within confines of a single
  network domain.
• The BDS works only within the wired networks.
• Venues for Research
• Is it possible to extend the BDS framework to
  multi-domain environment? How?
• Is it possible to extend BDS framework to mobile
  environment? How?

34
Summary

• The BDS architecture consists of
• The admission control
• The resource management mechanism
• The RDF protocol.
• The BDS provides
• Scalable architecture
• Supports per-flow QoS services
• Bandwidth guarantees
• Fair excess bandwidth distribution
• Congestion Control
• Dynamic per-flow Bandwidth allocation
• There is still plenty of research to be done!

35
Conclusions
Q How a student majoring in Computer Science
can join or start working on a research project?
A Talk to faculty at Computer Science Department.
Possible Scenarios a student comes to my office
and tells me that he/she wants to do research in

• Robotics
• Theory and AI
• Operating Systems
• Computer Organization
• Graphics and Visualization
• Others

• Computer Networks
• Quality of Service
• Internet Routing and BGP
• Mobile and Wireless Networks
• Network Security
• Others

• Other Areas of Science
• Underwater basket weaving
• Others

36
The End!
37
Implementation Issues Network Edges
38
Implementation Issues Network Edges
39
Implementation Issues Network Edges
40
Implementation Issues Network Edges
41
BDS Implementation
42
Spotlight on Faculty Research. This year the
Computer Science Department will be holding a
series of seminars to highlight research in the
field. Please make an effort to attend these
seminars, and don't be discouraged if a topic is
one that you may not be familiar with. Snacks
will also be served! The first presentation is
scheduled for Wednesday, November 17th at 1050
am in Robinson 101A.
Supporting per-flow QoS using the Bandwidth
Distribution Scheme. By Dr. Vasil Y. Hnatyshin 
 
Date Wednesday, November 17th Time 1050 am
Location Robinson building, Room 101 A.
43
Summary of the RDF Protocol
Phase Name Direction of info flow Initiate by Cause of Initiation
Path Probing Edge-to-Core Core-to-Edge Edge Routers Periodic
RBR Update Edge-to-Core Edge Routers Flow Activation or Flow Termination
Notification Core-to-Edge Core Routers Congestion
44
Summary of the RDF Protocol
Phase Name Updates Data Structures Carries Information
Path Probing Path Table (Edges) Link Table (Edges) Interfaces Table (Core) Edge node ID Path Characteristics
RBR Update Interfaces Table (Core) RBR Change values
Notification Path Table (Edges) Link Table (Edges) Congested Link Info