tcom513-lecture4.ppt
TRANSCRIPT
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
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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