tcom513-lecture4.ppt

TCOM 513Optical Communications

Networks

Spring, 2005

Thomas B. Fowler, Sc.D.

Senior Principal Engineer

Mitretek Systems

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Topics for TCOM 513

Week 1: Wave Division Multiplexing Week 2: Opto-electronic networks Week 3: Fiber optic system design Week 4: MPLS and Quality of Service Week 5: Optical control planes Week 6: The business of optical networking: economics

and finance Week 7: Future directions in optical networking

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Resources

www.sorrentonetworks.com/whitepapers.asp– Get their “IP over Optical” presentation

www.tellium.com/optical/presentations.html– Get “Convergence of IP and Optics”– Other presentations useful as well

www.nanog.org/mtg-9905/mpls.html– Right click and you can get the slides (Nortel)

www.cellstream.com/prod08.htm– Multiprotocol Label Switching– You’ll have to pay for this one: $27.95

www.itprc.com– Info about various routing protocols

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Resources (continued)

www.cis.ohio-state.edu/~jain/– Tutorials and papers on various networking subjects

from Raj Jain www.cisco.com/warp/public/503/2.html

– Cisco networking icons in various formats www.iec.org

– Download MPLS tutorial from Trillium

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Topics

Switching problem and label switching

MPLS

MPS

Current Network Problems

Enhancing Internet Protocol (IP) Networks To Support A Variety of Applications

Quality of Service (QoS) As A Solution

Real-time Application Protocols

Two Locations for QoS: Access And Backbone

Diffserv and QoS

Cyber Security and QoS

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Economic reality: Carrier’s dilemma

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How can carriers find new high-margin service offerings?

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Network reality—SONET infrastructure

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Network reality: DWDM

• Most packet data networks are meshed

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How to best marry these three…

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Fundamental conflicts

Topology and technology– Data networks on SONET and DWDM– Some services still require SONET 50 msec restoration

Economics– Packet data networks are naturally resilient

• May not justify cost for SONET redundancy in order to collect lower revenue for “best effort” service

– Providers are looking for network to support voice, private line, data with same infrastructure

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How to deal with problem and retain (or improve) profitability Migrate to intelligent optical networking

– Offer new services• Higher bandwidth services• Optical VPNs: Public services that act like private

networks– Migrate to mesh when and where appropriate

• Dedicated 50msec restoration for those services requiring it (and willing to pay for it)

• Shared mesh restoration for resilient packet services (FR, ATM, IP)

– May save up to 60% in costs– Send IP and Optical to marriage mediation

• Must learn to live together• Divorce is not an option

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General approach

Virtualization– Virtual: has same functionality as a particular physical

network, but does it through emulation (essentially software)

– Make physical networks more virtual• To speed provisioning• To allow faster upgrades

– Make virtual networks more physical• To reduce overhead

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Problem: routers have limited visibility

Routers do not naturally see– Rings– Connections

• Native IP is connectionless protocol Routers do see

– Ports and addresses (i.e., routing tables)– Proprietary QoS queues

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Brief historical background

Early Internet was concerned only with mechanics of reliable data transfer– Simple applications such as FTP, remote login– Used software-based routers

Later devices that could switch in hardware at levels 2 and 3 had to be deployed– Layer 2 switching: addressed bottlenecks in LANs– Layer 3 switching: addressed bottlenecks in layer 3 routing by

moving route lookup to high-speed hardware Issues

– Did not address service requirements for info in packets– Based on shortest path only

• No consideration of jitter, delay, congestion– Best effort utilizing algorithms in network components

• Little or no global control or optimization

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The switching problem

Application

Presentation

Session

Transport

Network

Data Link

Physical

OSI Reference Model

Doesn’t know anything

Knows about local workgroup

Knows about other workgroups

Workgroup Switch

Hub

Router

Repeater

Route/ Switch

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The switching problem (continued)

What does a switch do?– Establishes a path through a network end-end

(“connection”)– Example: circuit switch used in telephony– No need for decisions at each point along the way

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The switching problem (continued)

What does a router do?– Looks at incoming packet address and looks it up in

table to find outgoing port– No dedicated paths established (“connectionless”)– Router does not know total path– Dynamic paths

• Path for subsequent packets going to same destination may change due to congestion or other problems

– Requires seach

• Complexity ~ O(log2 n), where n is number of entries in routing table

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The switching problem (continued)

IP traffic: primarily routed ATM traffic: primarily switched

– Permanent virtual circuit (PVC) — fixed– Switched virtual circuit (SVC) — dynamic

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The switching problem (continued)

How to switch (route) packets with least expenditure of processing?

How to allow different services to coexist on same IP network?– At present, isochronous traffic (e.g., voice) does not

work if network utilization greater than about 25%– Requires QOS (quality of service) or COS (class of

service) How to allow different protocols on same network?

– IP– ATM– FR

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The switching problem (continued)

How to have a single packet forwarding method or paradigm while still allowing for different routing paradigms– OSPF: Open Shortest Path First– PNNI: Private Network to Node Interface or Private

Network to Network Interface• An ATM routing protocol

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Desired solution elements

Combine best of switching and routing Do routing once to find a path

– Record path elements– Apply tag to subsequent packets with path information– No need for looking into these packets to fetch

addresses and do lookups at each router– Complexity ~ O(1), because indexing is used

Initially called “Tag switching” or “Label switching” Similar (but not identical) to Post Office method

– Do handwriting recognition on a letter once– Encode address info at bottom of envelope with bar

code– Use bar code to route letter through mail system

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•BROADCAST: Go everywhere, stop when you get to B, never ask for directions.

•HOP BY HOP ROUTING: Continually ask who’s closer to B go there, repeat … stop when you get to B.

“Going to B? You’d better go to X, its on the way”.

•SOURCE ROUTING: Ask for a list (that you carry with you) of places to go that eventually lead you to B.

“Going to B? Go straight 5 blocks, take the next left, 6 more blocks and take a right at the lights”.

One of the many ways of getting from A to B:

Source: Nortel

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Label Switching

•Have a friend go to B ahead of you using one of the previous two techniques. At every road they reserve a lane just for you. At every intersection they post a big sign that says for a given lane which way to turn and what new lane to take.

LANE#1

LANE#2

LANE#1 TURN RIGHT USE LANE#2

Source: Nortel

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Basic idea behind label switching

Set up “virtual circuit” between source and destination Assign numbers to each path element Copy numbers to packets Switch packet based on number

– Ingress router or host applies label– Exit router strips it off

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Basic idea behind label switching (continued)

Forwarding of packets done using a short, fixed-length label rather than disassembly of complete address– Addressing scheme different for different protocols

(ATM, FR, IP, etc)– Labels identify streams of traffic– Label table much smaller than routing table

Each label represents a set of destination addresses– Packets with same label treated as a group, not

individually Utilizes Time-To-Live (TTL) counter accurately maintained Idea is similar to PVCs and SVCs

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Solution: Multiprotocol Label Switching (MPLS)

Layer 3 technology Works with any protocol, but primarily used for IP traffic Glues connectionless IP to connection-oriented networks

– IP to ATM– IP to optical networks

Referred to as “shim layer”– Something between layer 2 and layer 3 to make them fit

better

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Solution (continued)

Addresses problems of modern networks– Speed– Scalability– Quality of Service (QoS) management– Traffic engineering (TE)– Multiprotocol

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MPLS functions

Mechanisms to manage traffic flows of various granularities

Independent of layer 2 and layer 3 specs– But serves as “glue”

Maps IP addresses to fixed length labels to speed forwarding

Interfaces to existing routing protocols such as OSPF Supports IP, FR, ATM layer 2 protocols

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MPLS paths

Utilizes label-switched paths (LSPs)– Sequence of labels at every node from source to

destination– Each label represents a path between two nodes– Set up in two ways

• Hop-by-hop• Explicit routing

Label establishment– Prior to packet transmission (control-driven)– Upon detection of a certain flow (data-driven)

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MPLS devices

LSR: Label Switched Router– High speed router (switch) in core of MPLS network– Participates in establishment of LSPs

LER: Label Edge Router– Operates at edge of access network and MPLS network– Forwards traffic to MPLS network after establishing

paths and attaching labels

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Aggregating addresses in one label

Aggregating addresses may be done in different ways– Flow direction– Traffic priority– Traffic type– Source address

IP Destination

Label

85.32.16.122 225

114.42.77.33 225

16.33.41.76 225

131.33.55.19 225

Part of Label Information Base

Label Switched Path 225

Source: Cellstream

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There are many examples of label substitution protocols already in existence

ATM - label is called VPI/VCI and travels with cell. Frame Relay - label is called a DLCI and travels with frame. TDM - label is called a timeslot its implied, like a lane. X25 - a label is an LCN Proprietary PORS, TAG etc.. One day perhaps Frequency substitution where label is a

light frequency (or wavelength)?

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Route at edge, switch in core

Source: Nortel

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Label creation methods

Topology-based– Uses normal processing of routing protocols

Request-based– Uses processing of request-based control traffic

Traffic-based– Uses reception of packet to trigger assignment and

distribution of label

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MPLS terminology

Label: short, fixed length, contiguous bits, locally significant (i.e., on a single link)

Label switching router (LSR): Routers that use labels– Traditional router– ATM switch– FR switch– Optical switch

Forwarding equivalence class (FEC): Same path and same treatment => same label

Label switched path (LSP): Particular path through network MPLS domain: contiguous set of MPLS nodes in one

administrative domain

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MPLS terminology (continued)

MPLS edge node: ingress or egress node Label information base (LIB): label tables in each MPLS

node which contain path information associated with labels Label distribution protocol (LDP): Method for distributing

label information Flow: flow of data from one application to another Stream: Aggregate of one or more flows

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Label switched path (vanilla)

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Standard IP network

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Normal routing of packet

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Label distribution by MPLS

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MPLS switching through network

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Shim label for PPP traffic (most common in IP networks)

Packet structure

Link layer Header SHIM Network (IP) Layer Header Payload

MPLS label (Mlabel) Exper. S TTL0 19 20 22 23 24 31

Exper.=experimental; COS

S= Bottom of stack (for multiple labels)

TTL = time to live

Source: Cellstream

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Labels can be stacked

225 Exper. 0 10

33 Exper. 0 7

105 Exper. 1 3

Labels popped

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What happens when label looked up

Next destination to which packet to be forwarded is found The correct operation required to be performed on packet

before forwarding– Replace top label stack entry with a new one– Pop entry off stack (exposing next one down)– Replace top label stack, push one or more new entries

onto stack

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Forwarding results of lookup

IP Destination

Label

85.32.16.122 225

114.42.77.33 225

16.33.41.76 225

131.33.55.19 225

Label Switched Path 225

IP Destination

Label

85.32.16.122 33

114.42.77.33 196

16.33.41.76 75

131.33.55.19 196

LSP 33

LSP 196

LSP 75

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Labels can be merged

IP Destination

Label

85.32.16.122 225

114.42.77.33 225

16.33.41.76 225

131.33.55.19 225

Label Switched Path 225

IP Destination

Label

85.32.16.122 196

114.42.77.33 196

16.33.41.76 196

131.33.55.19 196

LSP 196

IP Destination

Label

211.35.45.8 33Label Switched Path 33

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Labels can also be tunneled

IP Destination

Label

85.32.16.122 225

114.42.77.33 225

16.33.41.76 225

131.33.55.19 225

LSP 225

IP Destination

Label

211.35.45.8 33LSP 33 LSP 33

LSP 225

LSP 99

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Routing protocols in MPLS

OSPF: Open Shortest Path First– Intended to yield better routing– Based on link-state technology– Allows Variable Length Subnet Masks (VLSM)– Other enhancements

BGP: Border Gateway Protocol– Purpose is to advertise to other routers what your

network can route to (internally) IS-IS: Intermediate System to Intermediate System

– Authentication between routers

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Summary of motivations for MPLS

Simplified forwarding based on exact match of fixed length label– Initial drive for MPLS was based on existence of cheap,

fast ATM switches Separation of routing and forwarding in IP networks

– Facilitates evolution of routing techniques by fixing the forwarding method

– New routing functionality can be deployed without changing the forwarding techniques of every router in the Internet

Facilitates the integration of ATM and IP– Allows carriers to leverage their large investment of

ATM equipment

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Summary of motivations for MPLS (continued)

Enables the use of explicit routing/source routing in IP networks– Can be easily used for such things as traffic management,

QoS routing Promotes the partitioning of functionality within the network

– Move granular processing of packets to edge; restrict core to packet forwarding

– Assists in maintaining scalability of IP protocols in large networks

Improved routing scalability through stacking of labels– Removes the need for full routing tables from interior routers

in transit domain; only routes to border routers are required Applicability to both cell and packet link-layers

– Can be deployed on both cell (eg. ATM) and packet (eg. FR, Ethernet) media

– Common management and techniques simplifies engineering

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Generalized MPLS (sometimes referred to as MPS) or GMPLS

MPS = Multiprotocol Lambda Switching Generalizes MPLS to deal with optical networking

– Photonic switches (PXCs)– Optical Cross Connects (OXCs)– Add/Drop Multiplexers (ADMs)– DWDM– Wavelength router

Attempts to utilize as much of MPLS engineering as possible

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GMPLS (continued)

Requires rethinking of some concepts– How label switching can be done– What edge devices should see

Solution: Use control plane of MPLS– Labels can’t be applied to optical packets– Must switch something labels can be applied to:

wavelengths– To implement new functionality

• Dynamic provisioning (“Point and click”)• Enhanced network survivability/restoration• Flexible signaling and control architecture to support

new applications

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QoS and MPLS, MPS

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Current Inter-Networking Environment

Current data Internet Protocol (IP) networks deliver packets on a “best effort” basis

– Meets requirements for data applications

• E-mail, file transfer, Web-browsing

– Does not meet requirements for real-time traffic

• Voice and video calls

• Collaborative conferencing

• Broadcast and multi-cast applications

– Provides no protection against cyberthreats such as Distributed Denial of Service (DDoS) attacks

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Current Voice and Video Networks Voice networks

– Circuit-switched Time Division Multiplexed (TDM) networks, e.g., worldwide Public Switched Telephone Network (PSTN)

• Fixed connection bandwidth ( 64 Kbps), constant delay, no jitter, no data loss, highly available

Video networks– Predominantly based on Integrated Services Digital Network

(ISDN)• Connection-oriented with fixed bandwidth ( 64 Kbps, 128 Kbps,

384 Kbps, 768 Kbps, 1.544 Mbps), constant delay, no jitter, no data loss, highly available

Broadcast NTSC video distribution– 45 Mbps T3-based TDM network

20-year-old technology, deployed in the mid-1980s

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Enhancing Internet Protocol (IP)

Networks To Support A Variety

Of Applications

58ControlNumberChallenge: Enhancement of IP Infrastructure to Support Diverse Set of Applications Service providers and network managers operating multiple

networks to support range of applications

– This is not desirable from economic and maintenance standpoint

IP infrastructure devices becoming cheaper due to proliferation of the public Internet and private networks

– Routers/switches and transmission

Current IP infrastructure needs enhancement to support voice, video, and data at acceptable levels

– Flow of real-time bit streams

This is the challenge for the decade

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Real-Time / Multimedia Requirements Support for a range of diverse applications

– Support for a range of bandwidth

• E.g., 128 Kbps collaborative video conferencing to 45+ Mbps video-on- demand

– Support for a range of performance for voice, video, multimedia, critical data

• Delay, delay variation, packet loss

Support a range of communication models

– Point-to-point, multipoint, multicast, broadcast

Use of QoS for cybersecurity looks promising

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Solution Alternatives Massive overbuild

– Brute force approach

• Feasible in good old POTS days

– Due to fractal nature of Internet traffic, difficult to know how much capacity is enough

• Fractal = self-similar on multiple time scales

Quality of Service (QoS) / Class of Service (CoS)

– Preferentially routes packets based on type of traffic they carry

– Does require software and / or hardware upgrades

Complex nature of Internet and other networks makes prediction of performance difficult

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Fractal Nature of Internet Traffic

Packets/100 msec

Packets/1 sec

Packets/10 sec

Packets/60 sec

Source: Willinger and Paxson, 1998

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Internet Time Scales

1 ms 10 100 1 s 10 100 1,000 104 105

Fractals:

Long-Range Dependency

Multifractals:

Effects of Network Transport Protocols

Diurnal and Other Effects

Measurement Time

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Invariants in Data TrafficInvariant Protocol level Distribution Parameters

Connection size - LognormalConnection duration - LognormalRequested file popularity Application ZipfRequested file sizes (overall) Application Hybrid: Lognormal body,

Pareto tail(Heavy-tailed)

HTML Size =4-6KBMedian: 2KBImages: 14 KB

FTP transfers Application Pareto tail(Heavy tailed)

Number of Page Requests/Site Application Inverse Gaussian(Heavy-tailed)

=3=9mode=1

Reading time/page (sec) Application Heavy-tailed 30median=7=100

Sessions (arrivals) Session PoissonSession duration Session Pareto

(Heavy-tailed)Session size Session Pareto

(Heavy-tailed)WAN traffic at TCP level Transport Self-similar

(fractal)TCP connections/Web session Transport Heavy-tailedInterarrival time of packets Data Link Heavy-tailed

(LRD, fractal)Cox model

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Determinants of Traffic Statistics

• Application structure• User behavior• File sizes

• Network control mechanisms

Monofractal scalingat time scales > 300 msec

Multifractal scalingat time scales < 300msec

WANs only

WANsandLANs

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Different Protocols Mean Different Time Scales

Internet Protocol (IP)

Transmission Control Protocol (TCP)

Ethernet

http ftp smtp

Packets

Packet streams

Multiple packet streams

ms

100’s ms

Minutes, hours

Traffic granularityT

ime

scal

e

.

.

.

Frames, bits100’s ns

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Quality of Service (QoS)

As A Solution

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What is Class of Service / Quality of Service ?

CoS– Classification of

packets for the purpose of treating certain classes or flows of packets in a particular way compared to other packets

QoS– QoS defined as user’s

experience over a network connection

Clearly, QoS will require some type of CoS

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QoS Metrics

Network delay Also known as latency

Delay variationAlso called Jitter

Throughput Packet rate (average, peak)

Packet loss rate Maximum rate at which packets can be discarded

Network service availability

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QoS / CoS Approach

Develop new protocols to support real-time applications

Split problem into access, backbone

– Develop appropriate access, backbone QoS

– Map access QoS (classes) into backbone QoS (classes)

Resolve issues to assure smooth end-to-end QoS as seen by user

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Real-Time Application Protocols

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New Protocols Providing Real-Time Support for IP Networks

New protocols developed for routing and switching of real-time traffic

– Multi-Protocol Label Switching (MPLS)

New protocols to support transport of real-time traffic

– Real-Time Transport Protocol (RTP)

– Real-Time Control Protocol (RTCP)

– Real-Time Streaming Protocol (RTSP)

New protocols to support real-time applications

– H.323 and Session Initiation Protocol (SIP)

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Real-Time Applications Protocol Stack

Presentation

Session

Transport

Network

Link

Physical

G.729(A)/G.723(.1)G.711

H.323/SIP/MGCP/RSVP/RTSP

RTP-RTCP/UDP

Network

IP (Use of IP Header for DiffServ)

- - - - - -

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MPLS for Real-Time Traffic Switching technology to support real-time flows in IP

networks

Designed to perform similar function to ATM Virtual Circuits

– Label Switched Path (LSP) pre-established to support specific QoS

– Label Distribution Protocol (LDP) used to accomplish this

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Stages of MPLS processing

Customer premises router supplies QoS info with each packet

Packet header examined at the entry point to MPLS network

– A “label” created by the edge router indicating packet classification

Core routers perform switching based on “labels”

– Only labels examined at intermediate points to support high-speed switching

• Less work involved compared to full packet processing

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MPLS for Real-Time Traffic (Concluded)

IP VPN (Virtual Private Network)

– A second unique “label” used to identify specific VPN packets

Works because label lookup is much faster than full address decoding

– Limitation is that number of labels << number of Internet addresses

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End-to-End QoS Model

Applications

Presentation

Session

Transport

Network

Data Link

Physical

InternetProtocol

(IP) or

Asynchronous Transfer Mode

(ATM)

Applications

Presentation

Session

Transport

Network

Data Link

Physical

802 Subnet Bandwidth Management (SBM)

ReSerVation Protocol (RSVP)

802 Subnet Bandwidth Management (SBM)

ReSerVation Protocol (RSVP)

ATM QoSor

IP QoS:Differentiated

Services (DiffServ)/MPLS

Access Network Backbone Access Network

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End-to-End QoS Model (Concluded)

Access QoS

– Must be granular enough to differentiate service requirements of multiple traffic streams

– Bandwidth control and traffic policing required at network entry points

Backbone QoS

– Backbone must provide enough transport and control to satisfy the service levels promised to customers

• IP QoS works on aggregate flows of traffic

• ATM QoS works on specific flows

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Two Locations for QoS:

Access and Backbone

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Access QoS

Access networks

– Customer premises networks

– Predominantly Ethernet LANs with IP

• Shared/switched Ethernet to desk-top

• Fast/Gigabit Ethernet backbone

No industry consensus on how to manage CoS/QoS at this level

– Some efforts made

• Signaling between client and bandwidth manager (RSVP)

• Priority of frames at Ethernet level (802.1p) to support QoS

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Backbone QoS: Two Options

ATM QoS

– Well-defined QoS for ATM service (connection-oriented)

IP QoS

– In evolutionary stage

• A range of protocols and architecture developed to support IP QoS

• Primary mechanisms within the switches/routers used are:

– Queuing of traffic based on classes

– Different forwarding priorities

– Different discard priorities

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Backbone QoS: ATM Wide Area Network (WAN)

Each ATM connection established to meet a specific QoS requirement

QoS specified during connections set-up time and can be re-negotiated during a connection

QoS in ATM networks characterized by a set of parameters

– Max Cell Transfer Delay (CTD)

– Cell Delay Variation (CDV)

– Cell Loss Ratio (CLR)

– Cell Error Ratio (CER)

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Backbone QoS: ATM Wide Area Network (WAN) (Concluded) A range of QoS-based services

– Constant Bit Rate (CBR)

– Variable Bit Rate real-time (VBRrt)

– Variable Bit Rate non-real-time (VBRrt)

– Available Bit Rate (ABR)

– Unspecified Bit Rate (UBR)

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DiffServ and QoS

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DiffServ Model

Problem: how do we know what classes of service are needed in order for user to experience desired QoS?

DiffServ model tries to answer this

– Defines an architecture for a set of service classes and QoS mechanisms for packet handling in those classes

• Not the same thing as MPLS

• Service providers providing Class of Service at ingress and egress points of MPLS IP networks trying to conform to DiffServ QOS

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DiffServ Model (Concluded) Provides a simple and coarse method of classifying

services of various applications

– Type of Service (ToS) field in IP version 4 has been renamed as DS (Differentiated Services) field (6 bits used)

– Following types of classes supported:

• Expedited Flows (EF)

• Assured Forwarding (AF) Class

Network edge devices assign DiffServ bits to packets for consistent treatment within the network

– Transit routers and switches will usually separate the traffic based on DiffServ bits into queues

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Classes of Services in IP Networks

Generally four traffic classes need to be supported at entry/exit points in IP networks

– Expedited flow For voice and network control

– Real-time traffic Mostly video applications

– Critical data Mission-critical data applications

– Best effort E-mail and browsing

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Current IP CoS/QoS Approaches for Backbone

Three basic approaches by service providers in near term

– No CoS/QoS support―pure IP routed backbone with Gigabit routers/Synchronous Optical Network (SONET) Transmission

– Support DiffServ-compliant CoS/QoS at Ingress/Egress points with no CoS/QoS support in the core MPLS backbone

– Support DiffServ-compliant CoS/QoS at Ingress/Egress points and use ATM-based QoS in the networking backbone

Future: IP-based QoS in backbone

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Option 1: No QoS Support in Backbone

Variant of massive overbuild strategy

Private networks only

– MPLS

– Gigabit routers

– SONET

High-speed (OC48+)

– Ensures low jitter, low utilization

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Option 2: DiffServ Compliant / No CoS/QoS Support in Backbone

Also for private networks

IP QoS supported only at entry and exit points of MPLS networks

– Entry and exit points represent bottlenecks, and, therefore, need priority management

– Very little traffic congestion in the backbone: Gigabit routers / Gigabit Dense Wavelength Division Multiplexing (DWDM) pipes

• May use Packet-over-SONET (POS)

Typically 50 msec delay coast-to-coast

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Option 3: DiffServ Compliant CoS/QoS at Ingress/Egress Points / ATM-Based QOS IP service provided over ATM cloud

ATM switches upgraded to support MPLS

– ATM services utilized to obtain desired QoS

SONET interfaces

Transit delays of 70 msec in backbone coast-to-coast

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Future: All-IP Networks With IP Over Optical

Internet Protocol

H.323/SIP/MGCP/RSVP/RTSPPPP/HDLC SRP 1/10 GE-MAC ATM SDL

H.323/SIP/MGCP/RSVP/RTSPSONET/SDH SONET/SDH 1/10 GE-PHY ATM-PHY SONET/SDHSDL-PHY

WDM / DWDM

Encapsulation

Optical Interface

Packet overSONET (PoS)PPP does L2

Functions

Dynamic PacketTransport (DPT)Spatial ReuseProtocol (SRP)

Intended forRing Architecture

GigabitEthernet

(GE)

AsynchronousTransfer

Mode(ATM)

SimpleData Link

(SDL)

Likely goal will be IP over DWDM, bypassing ATM and SONET QoS will have to be functional in this environment

Source: Cisco/Tomsu & Schmutzer

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Work To Be Done IP QoS implementation still evolving

No industry consensus on how IP LANs and IP MPLS WANs will work together to offer end-to-end QoS

– Number of traffic flows/priorities to be supported at entry/exit points

– Admission control and traffic management at entry/exit points of backbone need to be carefully managed

Role and value of MPLS support for CoS/QoS in the core switches/routers not clear

– Need for QoS support from MPLS?

Will depend on architecture

– IP over DWDM?

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Cyber Security and QoS

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Mitretek Laboratory Work on QoS and Cyber Security Cybersecurity has become issue of great importance for

Government and private sector

Mitretek has developed extensive capabilities to study network performance under QoS

– Laboratory

– Analytic / simulation

Capabilities can also be used to study various cyber attacks and performance of IP networks under congestion conditions

– DDoS attacks

– Congestion resulting from damage to links, switches, routers

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QoS and Cyber Attack Modules

Packet performance Resource utilization

LaboratoryTestbed

LaboratoryTestbed

OpNetSimulation

OpNetSimulation

AnalyticalModel

AnalyticalModel

Packet performance Resource utilization

Traffic profile

Up to 20 nodes network Validate the simulation

results using the testbed output

Up to 7 nodes network

Up to 1,000 nodes network Validate the analytic results

using the input from testbed or simulation

Traffic profile

Packet performance Resource utilization

Traffic profile

Network architecture Network protocol Routing topology QoS scenarios

Scenario Parameters

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Mitretek Lab Work on QoS and Cyber Security Three-node test to show effect of QoS on network flooding by

DDoS attack

37253725

SwitchSwitchSwitchSwitch

37253725

2621

37253725

26512651

26212621 SwitchSwitch

2651265126512651

26212621

QoS Enabled Path

2xT1

1xT1

FE

FE

FE

2xT1

1xT1

2xT1

1xT1

TrafficGenerator

QoS DisabledPath

Net Meeting Station

TrafficGenerator

TrafficGenerator

Net Meeting Station

Net Meeting Station

97ControlNumber

Link Utilization Near 100 Percent

98ControlNumber

Results of QoS

Video with QoS Video Without QoS

99ControlNumber

Analytical Studies of Networks Under Congestion and Cyberattack

Questions of interest in today’s environment– How vulnerable are large networks to attack?– Can we predict the performance of a network under

attack? Mitretek has developed an analytic model called the IP

Network Performance and Analysis Tool (IP-NPAT) and an OPNET simulation model to address these types of questions– Analyzes IP networks under variety of conditions

• Cyber attacks

• Implementation of new programs or protocols

– Developed to support Government agencies

100ControlNumber

Analytical Studies of Networks Under Congestion and Cyberattack (continued)

Analytic techniques allow Mitretek to study network congestion in the presence of heavy-tailed traffic distributions

Waiting time CDF for links cannot be calculated using queuing theory when traffic distributions are heavy-tailed

– Mitretek has developed a technique called the Transform Approximation Method (TAM) and its associated numerical procedure, called the TAM Recursion Method

– Allows end-to-end waiting times to be estimated in congested networks

101ControlNumberAnalytical Studies of Networks Under Congestion and Cyberattack (Concluded) Used in conjunction with laboratory studies

Comparison with simulations has verified accuracy of analytic methodology and tools

102ControlNumber

Comparison of Analytic and Simulation Results

0.00E+00

1.00E-01

2.00E-01

3.00E-01

4.00E-01

5.00E-01

6.00E-01

7.00E-01

8.00E-01

9.00E-01

1.00E+00

0 10 20 30 40 50 60 70 80 90 100

Time (msec)

P(t

< T

)

Sim CDF

Analytic CDF

103ControlNumber

Future enhancements/applications

Analytic model expanded to include– DiffServe– Voice, Video, Data packets– MPLS

Used to design secure networks