Transcript Bandwidth Assurance in a Differentiated Services Network

The Internet: Present
Broadband Packet Switching:
A Personal Perspective
2002.9.2
Meehwa Kim
Abstract
This article represents the author’s personal
perspective on the development of broadband
packet switching from 1980 to 1995.
Today’s Internet represents 0.1% of the
deployment of a national petabit broadband
packet network.
Along the deployment timeline, the author
describes the development of packet voice,
Ethernet bridging, ATM, gigabit testbeds, and
local ATM.
Discussing the efforts at transitioning the Internet
from academic to commercial service
Introduction
The author contributed to the development of
broadband packet switching and its use in the
modern Internet.
Two distinct milestones in Broadband packet
switching
 Voice network: ARPANET, U.S. PSTN
 BISDN
Voice over Ethernet
D. Sincoskie found that Ethernet would carry up to
150 simultaneous voice calls.
 the calls were coded at 64 kbps
 silent periods removed
This was enough to construct a 1000-line private
branch exchange (PBX).
In 1982, D. Sincoskie made a voice over Ethernet
cal.
 works with PSTN
 incorporated echo cancellers
Ethernet Bridges
Problems of Ethernet-based
 It could grow to 1000 phones carrying 200
conversations, but the system wasn’t scalable.
 Ethernet also didn’t work over long distances.
 ARPANET in 1983’s maximum speed was
56kb/s, less than the bit rate of a single packet
phone(64kb/s).
Ethernet Bridges
Ethernet Bridges
 Low-cost high-throughput devices to
interconnect Ethernets
 Routing seemed slow and complex, due to the
complexities of the IP protocol.
VLAN (Virtual LAN)
 Add some field in each packet
 Contribute for scaling multicasting, enabling
mobility, reducing extraneous broadcasting
The Challenge Expands:
The Birth of Broadband
Synchronous Wideband Switch (SWS)
 45 Mb/s digital cross-connect system
 Use packet technology at its core
 Basically a circuit switch
Problems of SWS
 How to resolve contention in a broadband
packet switch
 How to guarantee end-to-end performance in
a packet switched network
Experimental Research Prototype
Incorporate a broadband circuit switch for
voice and video applications
The ERP project demonstrated in 1987.
 A serial input packet switch at 56 Mb/s
 A 240 Mb/s circuit switch
 Packet access multiplexing at 150 Mb/s
 Integrated multimedia services: packet voice
and data, and circuit-switched video
Making Packet Network
Performance Deterministic
Questions of Packet Switching Performance
 Could packet switching meet the service requirement?
 Could packet networks perform like circuit networks?
Circuit Switching
 Strong point: extensibility
 Weak point: inefficient to multiservice networks
Packet Switching
 Weak point: problem of guaranteeing performance, delay
and packet loss rate
Making Packet Network
Performance Deterministic
Solutions
 Multi-rate circuit switching
 Dynamic TDM
 Stop and go queuing
Packet switching is better than TDM circuit
switching.
Eletropolitics
Big issues of Internet standard
 Packet vs. circuit switching
 Actual packet format
• In 1986, Internet and Ethernet both used variable
length datagrams with relatively large packet headers.
• Fixed-size packet became standard.
Eletropolitics
The BISDN carried voice.
Packet size
 U.S. standard: 64 bytes
 Europe standard: 16-32 bytes
 Japan standard: 66 bytes
 In 1989, ATM 53-byte cell became standard.
5-byte header, 48-byte body
Eletropolitics
Trend changes
 Ethernet, IP over SONET
 ATM served as an Internet backbone in the
1990’s.
 IP over Ethernet over WDM network will be
future access network.
Onward to a Gigabit
CNRI Gigabit testbed
 Four 155 Mb/s lines in parallel achieve 622
Mb/s throughput.
 622 Mb/s full-duplex ATM network could
transmit data at 1.244 Gb/s in both directions.
In 1993, project AURORA
 First wide-area ATM/SONET network
 2.5 Gb/s SONET backbone running from
Philadelphia to Boston
 155 and 622 Mb/s ATM host interfaces
Local ATM
Ethernet
 Dominant, but inefficient capacity
FDDI
 100 Mb/s rate, but not dominant
ATM
 Scalable, Industry standard for BISDN
 Problems of integrating ATM into TCP/IP
protocol stack
 Mid-1990’s enjoyed market place
 100 Mb/s speeds
Local ATM
Fast Ethernet
 Proposed in 1992
 100 Mb/s
 Advantage over ATM: Software compatible
Switched VLAN enabled 100 Mb/s.
Gigabit Ethernet dominate LAN market.
Commercializing the Internet
Issues of commercializing
 Commercial network needs multiple backbones.
 Multiple Internet access providers have to be
accommodated.
In 1993, NSF offered a new architecture
for a commercial Internet.
 Define NAP (network access point)
 Multiple backbone
• NSFNET: research and education purpose only
• Other commercial backbones
Conclusion
In this article, the author said that he want to
construct a national scale packet-switched
network supplying 150 Mb/s to every residence.
In the early 1980’s, the ARPANET had a total
capacity of 10 Mb/s and the PSTN had a terabit
capacity.
The total capacity of the U.S. Internet today is 1
Tb/s.
The envisioned broadband network would have
capacity of petabit.