B

CS6591 Communication Network Analysis and Design

Dr. Greg Bernstein

Multiple sources…

www.grotto-networking.com

Outline

• Why bother with network “concepts”?

• Initial Concepts:– “multiplexing”

– “inverse multiplexing”

– Switch “forwarding table”

– “control”, “management”, FCAPS

– “layers” and “partitions”

• Standards and Networking

• Networking isn't just IP...

Voice Hierarchies

• 64kbps were the foundation of the digital telephone system.

• Two major multiplexing hierarchies evolved from these DS0 channels. – The T1 hierarchy (https://en.wikipedia.org/wiki/T-carrier) and

the E1 hierarchy (https://en.wikipedia.org/wiki/E-carrier). – These hierarchies are more accurately referred to as PDH

(plesiochronous digital hierarchies). Exact specifications of some of these systems can be obtained free from the ITU-T (http://www.itu.int/rec/T-REC-G/e). In particular G.701-705.

• But wait voice communications is still alive and well and actually starting to sound better? – Yes, but we have largely abandoned 64kbps channels as a

foundation for networking!

Why bother with “concepts”?

• “Concepts”, “Abstractions”, and “Generalizations” in Networking: Why?

– Which is older circuit switching or packet switching? How old is networking? What is the biggest network in terms of $$$ traded?

– Origins of routing protocols

– The patent “game”

– Understanding a continuously changing field

“Package" Switching Example

• Daily Flight Segments: Domestic - 940; International - 1, 015

Airports Served: Domestic - 382; International - 346

Air Hubs:– United States: Louisville, KY (Main Global Air Hub); Philadelphia, PA;

Dallas, TX; Ontario, CA; Rockford, IL; Columbia, SC – Europe: Cologne/Bonn, Germany – Asia Pacific: Shanghai; Shenzhen; Hong Kong – Latin America and Caribbean: Miami, FL, USA – Canada: Hamilton, Ontario

UPS Air Operations

Largest $$$ Network in TradeC

on

tain

er

Sh

ippin

g

Ne

two

rk

s

From the Economist website

Container Shipping “Links”• Trade route information:

http://www.worldshipping.org/about-the-industry/global-trade/trade-routes

Origins of Routing Protocols and Queueing Theory

• The founders of the internet didn't invent the concept of “routing”! – Shortest path algorithms such as Bellman-Ford (1956)

– RIPv2-- and Dijkstra's algorithm (1959) –OSPF--came well before the internet! T-carrier didn't start to be deployed until 1962.

• Queueing theory – (https://en.wikipedia.org/wiki/Queueing_theory) goes

back to Markov (1906) and Erlang (1906 etc...). But we can use it over 100 years later to tell us about the packet delays in an IP router, or the dropping (on handoff) of a cellular phone call.

Understanding a continuously changing field…

• X.25 (1970)

• Frame Relay (1988)

• Asynchronous Transfer Mode (1990s)

• MPLS (1996, first RFCs 2001)

• What do these all have in common?

Networking Concepts

• Multiplexing

• Inverse multiplexing

• Data Plane

– Switch forwarding tables

• Control and Management Planes

• Layers and Partitions

Multiplexing

• N communicating entities

– Need N(N-1) unidirectional comunicaiton channels

Time Division Multiplexing Details

From ITU-T G.704

What’s this course about?

• Current topics and concepts in high speed networks!

• Contents have been changing based on evolving technologies and application areas.

• Hence we will cover :– Technologies and concepts: VPNs, MPLS, Optical,

GMPLS, advanced switches and router design, SDN, queueing theory/QoS

– Application areas: Data centers (cloud), enterprise, ISPs, carrier backbone

Time Division Multiplexing Details (icky!)From ITU-T G.704

FDM Free Space

spectowval.com

ptolemy.eecs.berkeley.edu

FDM in FiberFrom ITU-T G.694.1

https://en.wikipedia.org/wiki/Fiber-optic_communication

Try a quick check with c = 3.0e8 m/s

Inverse Multiplexing

• Concept

– Using multiple lower rate channels to create a single higher rate channel.

– Derives from idea of parallel processing

• Variations

– End to end, single hop

– Circuits or packets

– Layer: 1, 2, 3, or 7

VCAT Inverse Multiplexing

• Circuit based

• End-to-End

b1 b2 b3 b4 b5 b6

Ethernet Link Ethernet Link

Ethernet Packet

VCAT Member # 1

VCAT Member # 2

VCAT Member # 3

VCAT Ingress VCAT Egress

Transport Network

b1 b4

b2 b5

b3 b6

b1 b2 b3 b4 b5 b6

Ethernet Packet

The PPP Multilink Protocol RFC1990

• http://tools.ietf.org/html/rfc1990

BitTorrent (application layer)

• http://bittorrent.org/introduction.html• https://wiki.theory.org/BitTorrentSpecification

Conventional server approach

BitTorrent peer to peer approach

Ethernet LAG (802.1AX-2008)

Ethernet LAG (802.1AX-2008)

Ethernet LAG (802.1AX-2008)

Networking & Standards

• IETF RFCs– http://www.ietf.org/

• IEEE Standards– http://standards.ieee.org/about/get/

• ITU-T Recommendations– http://www.itu.int/en/ITU-

T/publications/Pages/recs.aspx

• Many others…– MEF, ONF, OIF, ETSI, ANSI, …

Uses of Layers in Networks

• Interoperability points– Physical and logical

• Management– Fault isolation, Performance monitoring (where

did the errors occur)

• Multiplexing and Switching– How signals/bits/bytes/packets get combined and

forwarded

– Not just one switching layer!!!

OSI Layer Models

– Useful for understanding data communication protocol relationships– Not really the full story…– https://en.wikipedia.org/wiki/OSI_layer

TCP/IP Layer Model

• Application• Transport

– TCP, UDP

• Internet– IPv4, IPv6

• Link• No physical?

– Flexibility to use different phylayers

https://en.wikipedia.org/wiki/TCP/IP_model

10G Ethernet Layer Model

• From IEEE 802.3 (2012) Section 4• Available from http://standards.ieee.org/about/get/• Why the extra layers/sublayers? PCS, PMA, PMD, XGMII

XGMII

• What is this?

• 10 Gigabit Media Independent Interface

– A SerDesH/W interface

From IEEE 802.3-2012 section 4

XGMII: A HW Layer/Interface

Nice 32 bit wide data busesFrom IEEE 802.3-2012

section 4

SDH/SONET Layers• ITU-T G.707 “Network node interface for the synchronous digital hierarchy (SDH)”• Available from http://www.itu.int/ITU-T/recommendations/rec.aspx?rec=8981• Why all these layers?

– Multiplexing/Switching and Management!

VT Path

STS Path

Tandem Connection

(optional)

Line

Section

Physical

Lower order

Virtual Containers

Higher order

Virtual Containers

Tandem Connection

(optional)

Multiplex Section

Regenerator Section

Physical

(a) SONET (b) SDH

Layers in TDM Networks

Regenerator

(3R) #1

Regenerator

(3R) #2

TDM de-

multiplexor

TDM

Multiplexor

= Optical Fiber

= Regenerator section overhead

= Multiplex section (line) overhead

= User traffic (path layer)

= Unused time slots

Path

MS

RS RS RS

Path

MS

RS

TDM Path

Multiplex Section

Regenerator

Section

TDM = Time Division Multiplexing like SONET, SDH, PDH, G.709, etc…

Optical Transport Network Layers

From ITU-T G.709

Layers in WDM Networks

Optical

Amplifier #1

Optical

Amplifier #2

Optical Add/

Drop

multiplexor

Optical

Multiplexor

Optical De-

multiplexor

= Optical Fiber

= Optical Support Channel

for “Transport layer”

= Optical Support Channel

for “multiplex layer”

OCh

OMS

OTS OTS OTS

OCh

OMS

OTS

OCh

OMS

OTS

Optical Channel

Optical Multiplex

SectionOptical Transport

Section

“Domains” – partitions of networks

• General Internet

– Autonomous Systems

• Intra-Domain Routing

– OSPF Areas

• Ethernet “LANs”

– Broadcast domains for Ethernet switches

• Link

– Between two nodes

Subnetwork Terminology

Network

Subnetwork C

C1

C2

C3

C4

C6

C7

C8

C9

C10

Subnetwork B

B1

B2

B3

B4

B6

B7

B8

End

system

A

End

system

ZLink

Node or

Network Element (NE)

Layers and Partitions

• Formal Models– ITU-T

• G.805• G.800• http://www.itu.in

t/ITU-T/recommendations/index.aspx?ser=G

– Open Grid Forum• Network Markup

Language• http://www.ogf.o

rg/documents/GFD.206.pdf

Ethernet Review• Reference Model (IEEE 802-2001)

Ethernet Frame

SFD = start of frame delimiter

IEEE 802.3-2012 part 1

Ethernet Addresses• Individual/Group• Unique/Locally Administered• First 24 bits form the Organizationally Unique Identifier (OUI)

From IEEE 802-2001

Ethernet Bridging

• Applies to “MAC” sublayer of layer 2

From IEEE 802-2001