Next Generation Networks

What’s New and What Isn’t

John C. Bellamy

Xalted Networks Inc.

Bellhead v. Nethead

• Circuit v. Packet

• Reliability v. Flexibility

• Line Protection v. Network Protection

• Hierarchical v. Flat Networking

• SONET v. Ethernet

• Conclusions

Integrated Voice Data v. Ethernet

IVD

Switch

PSTN

Mainframe/Server

(Switched Access)

PBX PSTN

(Shared Access)

Mainframe/Server

Ethernet

Twisted Pair Coax

Circa 1985

AT&T v. Ethernet

PSTN

(Shared Access)

Router

Ethernet

Switch

PSTN

(Switched Access)

RouterTwisted Pair

Coax

Circa 2001

Next Generation Digital Loop Carrier

Remote

Digital

Terminal

Local

Digital

Switch

IDT

TDM Digital Transmission

Hierarchical v. Flat Multiplexing

a) Transport of PDH Multiplexed DS1 Signals in SONET STS-1

b) Transport of VT1.5 Mapped DS1 Signals in SONET STS-1

DS2

DS0 DS0 DS0

DS1

DS2

... ......

DS3

STS-1

DS0 DS0 DS0

DS1

DS0 DS0 DS0

DS1

DS0 DS0 DS0

DS1

...

STS-1

VT1.5

DS0 DS0 DS0

DS1...

VT1.5

DS0 DS0 DS0

DS1...

VT1.5

DS0 DS0 DS0

DS1...

VT1.5

DS0 DS0 DS0

DS1...

VT1.5 VT1.5 VT1.5VT1.5

H H H

Data Data Data

c) Single Layer Multiplexing of Packet Switching

Complexity on the Edge

PSTN

Leased Circuits

PSN

PSN

PSN

PSN

R

R

Router (R) Store and Forward

Packet Switching Node (PSN)

PacketizationAddressing

Error ControlFlow Control

Reassembly

Old Generation Data Network

Circuit Emulation

ES/R

ES/R

ES/R

ES/R IP/ATMCore

New Generation Voice Network

R

R

Router (R) Store and Forward QoS

Edge Switch/Router (ES/R)

Adaptation Segmentation

Speech Compression

Voice Activity DetectionEcho Control

ReassemblyClock Recovery

Reliability v. Flexibility

• Tight Configuration Management

• Grade of Service Traffic Engineering

• Battery and Generator Power Back Up

• Line Powered 2500 Set Telephones

• Auto Discovery

• Best Effort

• UPS?

• Commercial Power CPE

Variable Length v. Fixed Length Addressing

EO

TO

EO EO

10 Digit

7 DigitDialing

4 DigitDialing

Dialing

End Office

Toll Office

PSTN Dialing Plan (Circa 1995)

R

R

R

R

IPv4 Addressing

32-bit AddressesProcessed byAll Routers

Fixed Length v. Variable Length Addressing

EO

TO

EO EO

10 Digit

10 DigitDialing

10 DigitDialing

Dialing

End Office

Toll Office

PSTN Dialing Plan (Circa 2001)

LSR

MPLS Addressing

Short Addresses (Tags)Processed byLabel Switched Routers (Switches)

LSR

LSR

LSR

SONET v. Ethernet

ADM

ESADM ADM

ADM

ADM

ADM

ES

ES

ES

ES

ES

Fast Ring Protection Switching Slow Network Layer Protection Switching½ Capacity Dedicated to ProtectionSymmetrical Bandwidth Allocation

No Bandwidth Reuse on Ring (UPSR)

All Bandwidth Available with Discretionary DiscardUnsymmetric Traffic Flows Supported

Coarse Bandwidth Granularity

Ethernet SwitchAdd/Drop Multiplexer

SONET v. Ethernet Augmentations

• Virtual Concatenation• Generic Framing

Protocol (GFP)• Hybrid Data Transport• Discretionary Traffic

• Quality of Service• Resilient Packet Rings• Ethernet over SONET

SONET Ethernet

Protocol Overlays

SONET/SDH SONET/SDH ATM Frame Relay

IP

IP

IP IPATM

Physical Transmission Layer

Ethernet

IP

Conclusions

• Different Portions of the Network will have Different Solutions

• SONET will live

• A Nationwide Transparent Optical Backbone will not Happen