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Trends in Networks. Varaiya - Walrand UC Berkeley 4/1998. 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

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Trends in networks l.jpg
Trends in Networks

Varaiya - Walrand

UC Berkeley

4/1998

  • 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


Trends in networks2 l.jpg
Trends in Networks

Varaiya - Walrand

UC Berkeley

4/1998

  • 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


Networking principles l.jpg
Networking 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 principles4 l.jpg

Driving Forces

Packets

Economies

Utility

Cost

Penetration

Critical

Networking Principles

Digital

Text

Picture

Video

Audio

Touch

Smell

Transmission

01001

Processing (Editing, Compression, Encryption)

Storage

Retrieval

Statistical Multiplexing

Error Control

Rate adaptation

Differentiated Service


Networking principles5 l.jpg

Internetworking

B|A| P

b | w |

B

A

R

a

b

v

w

v | a |

Networking Principles

B|A| P

B|A| P

Decoupling of protocols, packet formats, timing

Requires global addressing scheme + routing tables

Fragmentation may be needed


Networking principles6 l.jpg

Scalability

N’

1

N

2

1

N’ 1

N 2

N” 2

N’ 3

N 1

N” 2

N.S’

3

1

3

2

2

N.S

N.S.H’

N’ 3

N” 3

N.S’ 1

N.S 2

N.S.H

N”

Networking Principles

Addressing: Subnetting


Networking principles7 l.jpg

Scalability

Root

IP = R

edu: NS = E

com: NS = C

Local NS

edu?

Ibm.com: IP = I

....

X

E

berkeley.edu: NS = A

stanford.edu: NS = A’

berkeley.edu?

edu

IP = E

A

eecs.berkeley.edu?

eecs: NS = B

cs: NS = B’

berkeley.edu

IP = A

B

V

X

V

Diva: IP = V

Eclair: IP = V’

eecs.berkeley.edu

IP = B

Networking Principles

Naming: Domain Name System

X: diva.eecs.berkeley.edu?


Networking principles8 l.jpg

Control: Errors

Objective: Retransmit lost packets

A

B

Lost or corrupted

Networking Principles

B|A| # 27 | data | crc

B|A| # 27 | data | crc

Timeout

A|B| # 27 | ack | crc

B|A| # 28 | data | crc


Networking principles9 l.jpg

Control: Errors

Objective: Retransmit lost packets more efficiently

A

B

1

2

3

4

5

4

Timeout

Networking Principles

Window size = Max. # of outstanding packets


Networking principles10 l.jpg

Control: Flow

Objective: Don’t overwhelm the receiver

A

B

W

W

W’

W’

Networking Principles

W = receiver-advertised window


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Control: Congestion

Objective: Efficient and Fair Share of Resources

Max Min

20

30

10

10

Networking Principles

20

Algorithm: If ACKs are delayed, reduce window size;

Else, increase.

Note: Current algorithms are not very good.

Could be improved with router measurements.


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Networking 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


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Networking 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?


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VCI

MAC addresses

a

1

a | d |

5+48 bytes

640-1.5 kB

b

1

b | d |

c

a | d |

1

d

2

b | d |

PVC or SVC

S&F or cut-through

ATM

Gigabit Ethernet

LANs: Gigabit Ethernet vs. ATM


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MAC LANE

AAL

ATM

A

V

IP

LANE

AAL

ATM

C

S

Z

LANE

Server

LANE

B

W

AAL

ATM

D

LANs: Gigabit Ethernet vs. ATM

LAN Emulation

A -> B:

A -> V: P = [b|a|…]

V -> S: b = ?

S -> V: b on W

V -> W: P / AAL5

W -> B: P

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


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Gigabit Ethernet

ATM

Compatibility

Yes

With LANE

Setup

Easy

Define

VCs

QoS

Coming

Yes

Cost

Small

Medium

MAN

Gigabit Mesh

Router or

ATM

WAN

Router (DS or OS)

Router or

ATM

Predicted for many backbones

some LAN backbones

(between 10/100 LAN switches)

LANs: Gigabit Ethernet vs. ATM


Wans sonet sdh l.jpg

payload

R

SONET “PATH ”

R’

(Sync. to master clock)

Note: R’ may not

be synchronized!

control header

a b a b a b a b a

cbc bc bcbc

ADM

c

c

c

a

a

a

Byte interleaving

(synchronized)

Add-Drop

Multiplexer

WANs: SONET / SDH

OC-3 = 155 Mbps, OC-12 = 622 Mbps, OC-48 = 2.4 Gbps

OC-96 = 4.8 Gbps, OC-192 = 9.6 Gbps


Wans sonet sdh18 l.jpg

IP packet

PAD + CRC

ATM cells

AAL5

Last

SONET PATH

IP/ATM/SONET

WANs: SONET / SDH

ATM located in Path by using HEC of cells

(no additional framing bits required)


Wans sonet sdh19 l.jpg

SONET Paths

SONET ring

Case for IP / PHY

WANs: SONET / SDH

  • TDM not ideal

  • Synchronization not needed if SM used instead of TDM

Proposal: Straight IP / PHY


Qos policy based switching l.jpg

Switch

Premium

HP

w = 6

R bps

Regular

LP

w = 4

QoS: Policy-Based Switching

Scheduling guarantees a fraction of bandwidth to user

small delays for premium service

Note: Should prevent excessive load (RSVP?)


Middleware caching pricing load balancing l.jpg

ISP

Intranet

Middleware: Caching, Pricing, Load Balancing

Where (in router or a special server?)

Static or dynamic?

Standards?

  • Pricing examples:

  • time/parameters

  • measured resource utilization

  • congestion pricing

  • auction pricing


Multicasting l.jpg
Multicasting

Replication by routers to link toward at least one

multicast “group member”


Multicasting23 l.jpg

Previous multicast

router replicates

packets

Non-Multicast

Router

MBONE:

Multicast using also

non-multicast routers.

Multicasting

[Tunneling between multicast routers and hosts]


Multicasting24 l.jpg

NACK implosion

=> NACK merging

Possibly: Caching in

“Designated Receivers”

NACKs

Errors

How to make multicast

reliable?

Multicasting

Note: Multiscale?


Voice over ip l.jpg

D

R

Voice Samples

Size

R (kbps)

IP Header (20 bytes)

D (ms)

Voice over IP

Tradeoff between

delay D and total rate R


Voice over ip26 l.jpg
Voice 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


Technology l.jpg

384 kbps

1.5 Mbps

(example)

Questions:

Pricing of services?

ADSL

Technology

Voice + IP Access

Competition with cable modems


Technology28 l.jpg

A

A

B

B

C

C

WDM

Technology

  • Laser spectra should be disjoint and

  • fit in low-loss window around 1.5 mm

  • Multiplies capacity of existing fiber


Technology29 l.jpg

IP Switching

D = net.host of destination

Must search in table

=> Limits throughput

D

net output port

Routing Table

TAG Switching

T = Tag placed by host or edge router

Smaller table (fast)

Policy-based tag

T D

T T’ output port

Routing Table

Switches

Technology


Technology30 l.jpg

Policy-based

Scheduler

(Linked lists)

Switches

Technology

Input/Output Buffering

Compromise Complexity of Scheduling / Throughput

Multicasting possible

Easier with fixed-size cells (e.g.., ATM core)


Active networks l.jpg
Active Networks

General ideas:

Network nodes programmable

(by user or manager)

Node interprets a program that specifies

how session packet should be handled

Examples:

Compression

Filtering (firewall)

Scheduling

Caching

Challenges:

Protection mechanisms

Standards


Security l.jpg

P = D(C; K)

C = E(P; K)

P

Alice

C

Bob

Eve

?

Security

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 = ...


Summary l.jpg
Summary

  • 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.

See references and web page for more details.


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