Trends in NetworksTrends in Networks• Networking Principles

• LANs: Gigabit Ethernet vs. ATM

• WAN: SONET/SDH

• QoS: Policy-Based Routing

• Middleware: Caching, Pricing, Load Balancing

• Multicasting: MBONE, Reliable

• Applications: Voice over IP

• Technology: ADSL, WDM, Switches

• Active Networks

• Security

Varaiya - WalrandUC Berkeley

4/1998

Trends in NetworksTrends in Networks• Networking Principles

• LANs: Gigabit Ethernet vs. ATM

• WAN: SONET/SDH

• QoS: Policy-Based Routing

• Middleware: Caching, Pricing, Load Balancing

• Multicasting: MBONE, Reliable

• Applications: Voice over IP

• Technology: ADSL, WDM, Switches

• Active Networks

• Security

Varaiya - WalrandUC Berkeley

4/1998

Networking PrinciplesNetworking Principles

• Driving Forces: Digital, Packets, Economies of Scale & Integration

• Internetworking: How do we connect different networks?

• Scalability: Hierarchical naming and addressing

• Error, Flow, and Congestion Control

• End-to-end Principle: Religion or Science?

Networking PrinciplesNetworking Principles Driving Forces

TextPictureVideoAudioTouchSmell

01001

Processing (Editing, Compression, Encryption)StorageRetrieval

Transmission

Statistical MultiplexingError ControlRate adaptationDifferentiated Service

DigitalPackets

Utility

Cost

PenetrationCritical

Economies

R

Networking PrinciplesNetworking Principles Internetworking

a

v

b

w

v | a | b | w |

AB

B|A| P

B|A| PB|A| P

Decoupling of protocols, packet formats, timingRequires global addressing scheme + routing tablesFragmentation may be needed

Networking PrinciplesNetworking Principles Scalability

N’ 1N 2N” 2

1

2

1

2

3N’ 3N 1N” 2

N

N.S

N.S.H

N.S.H’

N’

N”

N.S’1

23

N’ 3N” 3N.S’ 1N.S 2

Addressing: Subnetting

Networking PrinciplesNetworking Principles Scalability

Naming: Domain Name System

RootIP = R

eduIP = E

berkeley.eduIP = A

eecs.berkeley.eduIP = B

Diva: IP = VEclair: IP = V’

eecs: NS = Bcs: NS = B’

berkeley.edu: NS = Astanford.edu: NS = A’

edu: NS = Ecom: NS = C

Ibm.com: IP = I....

Local NS

X: diva.eecs.berkeley.edu?

X

edu?

E

berkeley.edu?A

eecs.berkeley.edu?

B

XV

V

A B

Objective: Retransmit lost packets

Networking PrinciplesNetworking Principles Control: Errors

A|B| # 27 | ack | crc

Lost or corruptedB|A| # 27 | data | crc

TimeoutB|A| # 27 | data | crc

B|A| # 28 | data | crc

A B

Objective: Retransmit lost packets more efficiently

Networking PrinciplesNetworking Principles Control: Errors

1

2

3

4

5

4Timeout

Window size = Max. # of outstanding packets

A BObjective: Don’t overwhelm the receiver

Networking PrinciplesNetworking Principles Control: Flow

WW

W’W’

W = receiver-advertised window

Networking PrinciplesNetworking Principles Control: Congestion

Objective: Efficient and Fair Share of Resources

20 30

20

10

10

Max Min

Algorithm: If ACKs are delayed, reduce window size; Else, increase.Note: Current algorithms are not very good. Could be improved with router measurements.

Networking PrinciplesNetworking Principles

End-to-End Principle: Religion or Science?

Principle: Don’t ask the network to do what hosts can do“Keep the network as simple as possible”

Motivation: Scalability: As more hosts are added, they can do more Upgradability: If most functions are in hosts, can upgrade Flexibility: Different hosts need different functions

Examples: Datagram Transmission in IP (no connection state in routers) Error/Flow/Congestion Control in TCP Compression, Encryption Soft-States (need to be refreshed) for multicast groups, RSVP

Networking PrinciplesNetworking Principles

End-to-End Principle: Religion or Science?

Limitations of End-to-End Principle:

Reservation of resources for QoS? Billing? Effective congestion control? Persistent connections for slow links?

Active networks may be a compromise?

LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM

ATM

1

1

2

1

VCI

PVC or SVC

5+48 bytes

Gigabit Ethernet

a

b

c

d

a | d |

a | d |

b | d |

b | d |

MAC addresses

S&F or cut-through

640-1.5 kB

LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM

A -> B: A -> V: P = [b|a|…] V -> S: b = ? S -> V: b on W V -> W: P / AAL5 W -> B: P

LAN Emulation

Applications/IP do not take direct advantage of QoS of ATM

A

B

C

V

W

D

Z LANEServer

S

LANEAALATM

MAC LANEAALATM

IPLANEAALATM

LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM

Gigabit Ethernet ATM

Compatibility Yes With LANE

Setup Easy Define VCsQoS Coming YesCost Small MediumMAN Gigabit Mesh Router or

ATMWAN Router (DS or OS) Router or

ATM

(between 10/100 LAN switches)

Predicted for many backbonessome LAN backbones

SONET “PATH ”payload

control header

R(Sync. to master clock)

WANs: SONET / SDHWANs: SONET / SDH

R’

Note: R’ may not be synchronized!

ADM

Add-DropMultiplexer

a b a b a b a b a

aaa

ccc

c b c b c b c b c

Byte interleaving(synchronized)

OC-3 = 155 Mbps, OC-12 = 622 Mbps, OC-48 = 2.4 GbpsOC-96 = 4.8 Gbps, OC-192 = 9.6 Gbps

IP packet

SONET PATH

WANs: SONET / SDHWANs: SONET / SDH IP/ATM/SONET

PAD + CRC

ATM cells

AAL5 Last

ATM located in Path by using HEC of cells(no additional framing bits required)

SONET ring

WANs: SONET / SDHWANs: SONET / SDH Case for IP / PHY

SONET Paths

•TDM not ideal•Synchronization not needed if SM used instead of TDM

Proposal: Straight IP / PHY

QoS: Policy-Based SwitchingQoS: Policy-Based Switching

Switch

Premium

Regular

HP

LP

w = 6

w = 4

R bps

Scheduling guarantees a fraction of bandwidth to usersmall delays for premium service

Note: Should prevent excessive load (RSVP?)

Middleware: Caching, Pricing, Load BalancingMiddleware: Caching, Pricing, Load Balancing

Intranet

ISP

• Caching of web pages• Billing for usage of link• Load balancing across servers

Where (in router or a special server?)Static or dynamic?Standards?

Pricing examples: • time/parameters• measured resource utilization• congestion pricing• auction pricing

MulticastingMulticasting

Replication by routers to link toward at least one multicast “group member”

MulticastingMulticasting

Non-MulticastRouter

MBONE:Multicast using alsonon-multicast routers.

Previous multicast router replicates

packets

[Tunneling between multicast routers and hosts]

MulticastingMulticasting How to make multicastreliable?

Errors

NACKs

NACK implosion => NACK mergingPossibly: Caching in “Designated Receivers”

Note: Multiscale?

Voice over IPVoice over IP

Tradeoff between delay D and total rate R

0

10

20

30

40

50

60

70

80

90

10 20 30 40 50

8-kbps

16-kbps

64-kbps

R (kbps)

D (ms)

IP Header (20 bytes)

Voice Samples

Size

RD

Voice over IPVoice over IP

Inside company: Single network Integration of services: voice mail, forwarding, call back, listen to email, read voice mail, translation, voice commands, encryption, integration with video, ...-> New products: PBX-IP, Phone-Ethernet

In Central Office: Switch-IP, Routing, Billing

TechnologyTechnology ADSL

Voice + IP Access

384 kbps

1.5 Mbps

(example)

Questions:

Pricing of services?

Competition with cable modems

TechnologyTechnology WDM

A

B

C

ABC

• Laser spectra should be disjoint and fit in low-loss window around 1.5 m

• Multiplies capacity of existing fiber

TechnologyTechnology Switches

D

D = net.host of destination

net output port

Must search in table=> Limits throughput

Routing Table

IP Switching

T D

T T’ output port

Smaller table (fast)Policy-based tag

Routing Table

TAG Switching

T = Tag placed by host or edge router

TechnologyTechnology Switches

SchedulerPolicy-based(Linked lists)

Input/Output BufferingCompromise Complexity of Scheduling / ThroughputMulticasting possibleEasier with fixed-size cells (e.g.., ATM core)

Active NetworksActive NetworksGeneral ideas:

Network nodes programmable (by user or manager)Node interprets a program that specifies

how session packet should be handled

Examples:CompressionFiltering (firewall)SchedulingCaching

Challenges:Protection mechanismsStandards

SecuritySecurity

C = E(P; K)

CAlice

Eve

Bob

P P = D(C; K)

?

Standards for E(.; K) and D(.; K) - Example: DES

Distributing K: Public Key (e.g., RSA) Trusted Certificate: Bob trusts Alice (trusted K, identity) Alice certifies: Jim’s Key = ...

SummarySummary

See references and web page for more details.

Future networks will probably see a larger role for• Gigabit Ethernet• DSL or cable modem• WDM• Hybrid (in/out buffer) Switches

The following features will be implemented• QoS• Billing• Reliability • Multicasting

Voice over IP and other real-time applications may become important.