Active networks and applications

1
Active networks and applications

• C. PHAM
• RESAM laboratory
• December 6th, 2000

2
Outline

• Introduction
• Nowadays network technologies
• Active networking
• Application Active Reliable Multicast
• Conclusions

3
Outline

• Introduction
• Nowadays network technologies
• Active networking
• Application Active Reliable Multicast
• Conclusions

4
The need for communication
5
The way people are communicating
6
Internet milestone
7
User perspective of the Internet
from UREC, http//www.urec.fr
8
What it is in reality
from UREC, http//www.urec.fr
9
Outline

• Introduction
• Nowadays network technologies
• Active networking
• Application Active Reliable Multicast
• Conclusions

10
Links the basic element for networking

• Backbone links
• optical fibers
• 40 to 60 GBits/s with DWDM techniques
• End-user access
• V.90 56KBits/s modem on twisted pair
• 512Kbits/s to 2MBits/s with xDSL modem
• 1Mbits/s to 10Mbits/s Cable-modem
• 64Kbits/s to 1930KBits/s ISDN access
• 9.6KBits/s (GSM) to 2MBits/s (UMTS)

11
Routers key elements of internetworking

• Routers
• run routing protocols and build routing table,
• receive data packets and perform relaying,
• may have to consider Quality of Service
  constraints for scheduling packets,
• are highly optimized for packet forwarding
  functions.

12
General architecture of an IP router

• receives input packets,
• sends packets to output buffers,
• transmits packets (with QoS?).

13
Desires put on the general Internet

• High-bandwidth
• for bandwidth-consuming applications
• Ubiquity of the network access (wireless, RTC,
  xDSL, mobile)
• for remaining connected everywhere
• Quality of Service
• for high-quality multimedia receptio
• Dynamicity, adaptability
• to take into account recent technologies

14
Challenges for the Internet

• high-speed www
• video-conferencing
• video-on-demand
• interactive TV programs
• tele-medecine
• high-performance computing, grids
• virtual reality, immersion systems
• distributed interactive simulations
• remote archival systems

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The reality(1)

• High-bandwidth accesses are not available for
  everybody
• high-bandwidth is achievable in the core network
  with optical fibers and DWDM techniques but,
• most end-users have an access ranging from
  56Kbits/s to 2Mbits/s and,
• it will be the case for many years!

16
The reality(2)

• An ubiquitous network access
• generally implies heterogeneity and asymmetric
  performances,
• how to take into account this heterogeneity?
• The heterogeneity of bandwidth makes QoS
• a difficult quest on an end-to-end basis,
• seems that QoS is the networking forever Graal

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The reality(3)

• New technologies require years to be deployed
• need for standardization
• IPv6, MPLS
• new services and protocols are costly to deploy
• many proprietary implementations, no
  interoperability of services and new technologies
• DiffServ, TagSwitching, LabelSwitching

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Towards a better Internet

• Interoperability of systems
• Rapid deployment of new services, accelerating
  infrastructure innovation
• Take into account the heterogeneity of needs and
  network accesses
• Customization of services, application-oriented
  processing features

19
Towards the concept of

• Introduction
• Nowadays network technologies
• Active networking
• Application Active Reliable Multicast
• Conclusions

20
What is active networks?

• Programmable nodes/routers
• Customized computations on packets
• Standardized execution environment and
  programming interface
• No killer applications, only a different way to
  offer high-value services, in an elegant manner
• However, adds extra processing cost

21
Motivations behind Active Networking

• From the user perspective
• applications can specify, implement, and deploy
  (on-the-fly) customized services and protocols
• From the operator perspective
• reduce the latency/cost for new services
  deployment/management
• From the network perspective
• globally better performances by reducing the
  amount of traffic

22
Active networks implementations

• Discrete approach (operator's approach)
• Adds dynamic deployment features in nodes/routers
• New services can be downloaded into router's
  kernel
• Integrated approach
• Adds executable code to data packets
• Capsule data code
• Granularity set to the packets

23
The discrete approach

• Separates the injection of programs from the
  processing of packets

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The integrated approach

• User packets carry code to be applied on the data
  part of the packet
• High flexibility to define new services

data
25
An active router
some layer for executing code. Let's call it
Active Layer
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Interoperability with legacy routers
APPLI
APPLI
traditional IP routing
AL
AL
AL
AL
TCP/UDP
TCP/UDP
TCP/UDP
TCP/UDP
IP
IP
IP
IP
IP
IP
27
Some open problems

• Security and integrity
• how to be sure that user code are safe?
• Performances
• how to add active computation without weeping out
  performances?
• Standardization of programming interface
• How to bill the CPU time?

28
Some active network applications

• Customization of services
• Web-caching, on-the-fly compression/encryption
• Filtering
• Auction, Distributed Interactive Simulations
• Firewall
• Congestion control
• QoS
• Network management
• Reliable multicast
• Middleware collective operation

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Where to put active components?

• In the core network?
• routers already have to process millions of
  packets per second
• gigabit rates make additional processing
  difficult without a dramatic slow down
• At the edge?
• to efficiently handle heterogeneity of user
  accesses
• to provide QoS, implement intelligent congestion
  avoidance mechanisms

30
ISDN xDSL
PSTN
GSM, UMTS
10Mbits/s
core network Gbits/s
Server
100Mbits/s
wireless LAN 1Mbits/s, 10MBits/s
visio-conferencing
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Outline

• Introduction
• Nowadays network technologies
• Active networking
• Application Active Reliable Multicast
• Conclusions

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Unicast

• Problem
• Sending same data to many receivers via unicast
  is inefficient
• Example
• Popular WWW sites become serious bottlenecks

Sender
R
from Gordon Chafee, http//bmrc.berkeley.edu/peopl
e/chaffee
33
Multicast

• Efficient one to many data distribution

Sender
R
from Gordon Chafee, http//bmrc.berkeley.edu/peopl
e/chaffee
34
Multicast

• History
• Long history of usage on shared medium networks
• Data distribution
• Resource discovery ARP, Bootp, DHCP
• Ethernet
• Broadcast (software filtered)
• Multicast (hardware filtered)
• Multiple LAN multicast protocols
• DECnet, AppleTalk, IP

from Gordon Chafee, http//bmrc.berkeley.edu/peopl
e/chaffee
35
IP Multicast Introduction

• Efficient one to many data distribution
• Tree style data distribution
• Packets traverse network links only once
• Location independent addressing
• IP address per multicast group
• Receiver oriented service model
• Applications can join and leave multicast groups
• Senders do not know who is listening
• Similar to television model
• Contrasts with telephone network, ATM

from Gordon Chafee, http//bmrc.berkeley.edu/peopl
e/chaffee
36
IP Multicast

• Service
• All senders send at the same time to the same
  group
• Receivers subscribe to any group
• Routers find receivers
• Unreliable or reliable delivery
• Reserved IP addresses
• 224.0.0.0 to 239.255.255.255 reserved for
  multicast
• Static addresses for popular services (e.g. SAP)

from Gordon Chafee, http//bmrc.berkeley.edu/peopl
e/chaffee
37
Example video-conferencing
from UREC, http//www.urec.fr
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video-conferencing (2)
224.2.0.1
Multicast address group 224.2.0.1
from UREC, http//www.urec.fr
39
Multicast difficulties

• At the routing level
• management of the group address (IGMP)
• dynamic nature of the group membership
• construction of the multicast tree (pruning)
• multicast packet forwarding
• At the transport level
• reliability, loss recovery strategies
• flow control
• congestion avoidance

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Reliable multicast

• What is the problem of loss recovery?
• feedback (ACK or NACK) implosion
• replies/repairs duplications
• adaptability to dynamic membership changes
• Design goals
• reduces recovery latencies
• reduces the feedback traffic
• improves recovery isolation

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Solutions

• Traditional
• end-to-end retransmission schemes
• scoped retransmission with the TTL fields
• receiver-based local NACK suppression
• Active contributions
• cache of data to allow local recoveries
• feedback aggregation
• subcast

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A step toward active services LBRM
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Active local recovery

• routers perform cache of data packets
• repair packets are sent by routers, when
  available

data
data
data5
data1
data2
data1
data3
data2
data4
data3
data5
data4
data5
data4
data1
data2
data3
data5
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Active feedback aggregation

• Routers aggregate feedback packets

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Active subcast features

• Send repair packet only to the relevant set of
  receivers

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Active Reliable Multicast Mechanisms

• Answer general questions such as
• is active networking beneficial for multicast?
• where active components should be placed?
• in what proportion?
• how fast do they need to be?
• Answer specific questions such as
• what mechanisms (global vs local NAK suppression,
  subcast facilities) for what performance?
• scalabity of the proposed solutions?
• Design of new multicast protocols

47
Network model

• F active routers among N.
• B receivers in a local group
• 2 kinds of receivers linked and free

48
Benefit of global aggregation on throughput
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Benefit of the source subcast facility
50
Impact of active router density
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Conclusion
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References

• D. L. Tennehouse, J. M. Smith, W. D. Sincoskie,
  D. J. Wetherall, and G. J. Winden. A survey of
  active network research. IEEE Communications
  Magazine, pages 80--86, January 1997.
• L. Wei, H. Lehman, S. J. Garland, and D. L.
  Tennenhouse. Active reliable multicast. IEEE
  INFOCOM'98, March 1998.
• M. Maimour, C. Pham. A Throughput Analysis of
  Reliable Multicast Protocols in an Active
  Networking Environment. TR. http//resam.univ-lyon
  1.fr/cpham/Paper/TR/TR01-2000.ps.gz

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Web links

• ANTS
• http//wind.lcs.mit.edu/activeware
• Tamanoir and active reliable multicast
• http//resam.univ-lyon1.fr
• Active Networking in France
• http//www.loria.fr/festor/raf/raf.html