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QoS for Virtual Private Networks over Optical WDM Networks

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General Process to Setup VPN. Heuristic Algorithm ... First, Type 1 (dedicated VPN) setup. Second, Type 2 (shared VPN) setup ... Lightpaths setup ... – PowerPoint PPT presentation

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Title: QoS for Virtual Private Networks over Optical WDM Networks


1
QoS for Virtual Private Networks over Optical
WDM Networks
  • Yang Qin (yqin_at_eecs.wsu.edu)
  • DAWN Lab
  • Postdoctor, EECS, WSU,
  • Pullman, WA

2
Organization
  • Introduction
  • Existing Works
  • Our Proposal
  • Some Results

3
Introduction
  • Wavelength Division Multiplexing (WDM)
  • Allow multiple simultaneous transmission at
    different wavelengths over a single fiber.
  • WDM networks
  • Broadcast-and-Selected WDM networks for local
    area network (LAN)
  • Wavelength routing networks for wide area network
    (WAN)

4
Introduction
  • WDM wide-area network

B
A
1
2
3
E
4
5
D
C
Optical Switch Node
Access Node
5
WDM Networks
  • Each switch node is equipped with transmitters,
    receivers and converters
  • A lightpath is defined as an all optical
    connection from the source node to the
    destination node.
  • Without a wavelength conversion, an optical
    connection (lightpath) can be established only if
    the same wavelength is available on all links.

6
Virtual Private Networks
  • A VPN may be defined as an overlay network that
    is built above a public network infrastructure,
    providing the VPN user with a private network
    through tunneling, encryption and authentication
    mechanism.
  • To the user, a VPN looks like a private networks,
    even though it is sharing a web of cables with
    the traffic of other users at the same time.

7
Virtual Private Network
  • Types of VPNs
  • There are more than one shared public networks,
    then VPNs can be established on either of them.
  • VPN over Internet, VPN over Frame Relay, VPN over
    ATM.
  • VPN over Internet is the most popular one.

8
VPN over Internet
  • Advantages cost-effective, flexible
  • Disadvantages unreliable, no quality of service
    providing
  • How a VPN over Internet works
  • Tunneling
  • Encryption
  • Authenticated

9
VPN over Internet
  • Tunneling
  • Tunneling is the technology that puts the virtual
    in VPN by letting one system send its data to
    another system using the Internet or some other
    networks connection.

Old payload
New IP Header
IP Header
New payload
10
VPN over Internet
  • Encryption
  • Encryption is a way of scrambling data so that
    only those people who are supposed to read it can
    read it by using a special key at the sending and
    receiving end.

The Internet
Plain text
Plain text
Cipher text
Cipher text
11
VPN over Internet
  • Authentication
  • Authenticating is the first step to make sure
    that whoever is logging on is who he says he is
    and has the right to enter.
  • Once the user has been authenticated, there is
    the issue of exchanging and managing the keys
    that the users need to communicate as their
    permission allows.

12
Problem of VPN over Internet
  • QoS is difficulty to guarantee when traffic is
    encrypted because the bits marking QoS cannot be
    read by routers.
  • Tunneling protocol over Internet can not
    guarantee the minimum delay because of the IP
    best-effort service characteristics.

13
Problem of VPN over Internet
  • In Internet VPN, since QoS by application is not
    an option offered by any service provider so far,
    therefore E-mail gets the same priority as
    resource management application.
  • Therefore, the current VPNs will be limited to
    handling low-priority enterprise traffic.
  • We need to deploy new kinds of VPNs to compete as
    mission-critical transport.

14
VPN over WDM
  • Motivation
  • By employing VPNs over WDM, we can eliminate some
    upper protocol layers, thus increase the overall
    effeciency of communication.
  • Multiple alternative optical paths inherently
    have different quality of optical transmission,
    therefore it is possible to provide diverse QoS
    for different traffic streams at optical layer.

15
VPN over WDM
  • Framework of VPN over WDM

VPN3
B
VPN1
A
1
2
Wavelength Routing Networks
VPN2
3
4
D
C
Optical Switch Node
VPN2
VPN1
VPN1
VPN3
Access Node
16
VPN over WDM
  • Problem formulation
  • Given a physical topology, number of wavelengths
    on each link, number of transmitters and
    receivers.
  • A set of VPNs traffic demands with different
    requirement of QoS.
  • Objective function maximize the quantity of
    carried traffic of VPNs we can support, subject
    to the physical constraints and satisfaction of
    the QoS requirement.

17
VPN over WDM
  • There are total V VPNs, N nodes in the networks.
  • Is the carried traffic demand for
    VPN I of type P from source S to destination D.
  • It is a NP complete problem.

18
VPN over WDM
  • Types of QoS we provide
  • Type 1 Exclusive VPNs, this kind VPN has a
    dedicated optical lightpath, with the highest
    priority of transmission on this lightpath.
  • Type 2 Shared VPNs, the paths of such VPNs have
    to share some lightpath with other VPNs on some
    physical links.
  • For this type, an appropriate mechanism is needed
    to schedule the VPNs which shared the same
    lightpath.

19
VPN over WDM
  • For Type 2 Generally, for some VPNs which could
    not use the lightpath, they have to hold their
    signals in the electronic queue.
  • Type 3 Multi-hop VPNs, for this kind of VPNs,
    there may not be any single hop lightpath setup
    for their traffic demands. They need to use
    multi-hop paths which will experience E/O and O/E
    exchange at the junction between two lightpaths.

20
VPN over WDM
  • Key advantages
  • It can facilitate the guarantee of diverse QoS
    requirement from different VPNs.
  • It eliminates the often complex QoS related
    functions in the upper protocol layers, thus
    increase the overall communication efficiency.
  • This could be the first step toward providing
    fine grained service over optical wide-area
    networks.

21
General Process to Setup VPN
  • Heuristic Algorithm
  • The basic idea is to establish lightpaths in
    descending order of the traffic matrix entries.
  • Three steps
  • First, Type 1 (dedicated VPN) setup
  • Second, Type 2 (shared VPN) setup
  • Lastly, Type 3 (Multi-hop VPN) setup

22
An Example for VPNs Setup
  • A sample networks

4
2
1
1
8
2
2
3
5
2
2
4
23
An Example Traffic Matrix
24
Lightpaths setup
  • We assume there are two wavelengths on each
    physical link, use 5 units as the capacity
    threshold. The following lightpaths are setup,
    (4,5) will use 4,5,W1 and 4,5,W2, (2,5) will
    use 2,3,5,W1 and 2,3,5,W2, (1,2) will use
    1,2,W1 and 1,2,W2, (5,3) will use 5,3,W1
    and 5,3,W2, etc. (5,2) traffic pair could not
    be assigned lightpath, since 5,3 are not used,
    and will be dropped to Type 3 service.

25
Simulation Discussion
  • Our simulation is based on a given physical
    topology, including the number of network nodes,
    number of wavelengths, number of transmitters and
    receivers.

26
Simulation Discussion
  • In our simulation, packet generate rate are
    following Poisson distribution.
  • Since the QoS Type 1 has its dedicated
    wavelength for its lightpath, therefore there
    will be no waiting time for the packets from this
    kind of VPN, in the simulation, we do not make
    experiment for Type 1.

27
Simulation Discussion
  • We consider the QoS Type2 and QoS Type3.
  • We assume the O/E/O exchanging takes about 20
    times the time of transmission time of one
    packet.
  • We study the performance when system parameters
    change, e.g. number of wavelength, number of VPN,
    and packet generate rate.

28
Simulation Results
  • Physical Topology

29
Simulation Discussion
  • We assume transmission time for one packet is one
    slot.
  • In the simulation, we first route the packet from
    QoS Type2, then search path for QoS Type 3 in the
    existing and remain lightpaths which are
    currently not be used by QoS Type2.
  • The following are the delay measured in slots for
    QoS Type2 and QoS Type3.

30
Delay versus Wavelength No.
31
Delay for Type 2 and 3 Traffic
32
Delay versus Traffic Loading
33
Delay for VPNs with Single Lightpath and Heavy
Traffic
34
Delay for VPNs with Multiple Lightpaths with
Heavy Traffic
35
Delay versus VPN No.
36
Algorithm for VPNs Setup
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