Active networks and applications

C. PHAMRESAM laboratory

December 6th, 2000

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Outline

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

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Outline

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

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The need for communication

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The way people are communicating…

Internet

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Internet milestone

1960 DoD project for a reliable, flexible network

1968 First transit node by BBN on DDP 316ARPANET was born with 4 transit nodes1969

1974 TCP/IP for internetworking

ARPANET has 200 transit nodes1983ANSNET from MERIT, MCI, IBM1990

Internet as you know it 1995

2000Internet 2, NG

??Something really fast

ATM, QoS,RVSP, DiffServ,IPv6, MPLS…

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User perspective of the Internet

from UREC, http://www.urec.fr

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What it is in reality…

from UREC, http://www.urec.fr

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Outline

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

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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)

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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.

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IP packet

IP packet

Filter Action

Forwardingtable

Routingagent

IP input processing IP output processing

IP packet

Packet scheduler

IP output processing

IP packet

Packet scheduler

General architecture of an IP router

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

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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

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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!

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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

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Towards the concept of…

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

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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

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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

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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

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DataData

The discrete approach

Separates the injection of programs from the processing of packets

active code A1

active code A2

A1A2

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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 code

data datacode

data

datadata

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An active router

IP packet

IP packet

Filter Action

Forwardingtable

Routingagent

IP input processing IP output processing

IP packet

Packet scheduler

IP output processing

IP packet

Packet scheduler

some layer for executing code.Let's call it Active Layer

AL packet

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Interoperability with legacy routers

IP IP IP IP IP IP

TCP/UDP TCP/UDP TCP/UDP TCP/UDP

AL AL AL ALtraditional IP routing

APPLI APPLI

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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?

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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…

core networkGbits/s

wireless LAN1Mbits/s, 10MBits/s

PSTN

10Mbits/s

GSM, UMTS

visio-conferencing

ISDNxDSL

100Mbits/s

Server

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Outline

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

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Unicast

R

Sender Problem Sending same

data to many receivers via unicast is inefficient

Example Popular WWW

sites become serious bottlenecks

from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee

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Multicast

R

Sender Efficient one to many data distribution

from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee

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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/people/chaffee

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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/people/chaffee

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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/people/chaffee

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Example: video-conferencing

from UREC, http://www.urec.fr

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video-conferencing (2)

Multicast address group 224.2.0.1

224.2.0.1

from UREC, http://www.urec.fr

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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

data1data2data3data4data5

datadatadata5

NACK4data4

data1data2data3data4data5

data1data2data3data5

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Active feedback aggregation

Routers aggregate feedback packets

NACK4

NACK4

NACK4

NACK4data4

NACK4

only one NACK is forwarded to the source

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Active subcast features

Send repair packet only to the relevant set of receivers

NACK4

NACK4

NACK4

data4

data4

data4

data4

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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

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Network model

F active routers among N.B receivers in a local group2 kinds of receivers: linked and

free

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Benefit of global aggregation on throughput

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Benefit of the source subcast facility

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Impact of active router density

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Conclusion

Zut, j'aurais mieux fait de

rester au séminaire!!

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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-lyon1.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