802.11n - increased speed increased complexity
DESCRIPTION
Watch the full OnDemand Webcast: http://bit.ly/wcincreasing80211 Making the move to 802.11n? Though the rewards are significant, they come with a cost. The increased complexity of 802.11n can be a bit maddening, and it will definitely impact the way you design, monitor, and maintain your WLAN. MIMO? Channel bonding? Aggregation? If these terms aren’t currently part of your WLAN vocabulary, they certainly will be by the time you make the move. And even though the specification has been ratified for some time now, 802.11n hardware continues to evolve. Join us as we explore the number of MIMO streams, channel bonding, guard interval lengths, and other characteristics that define your WLAN capabilities. We’ll also characterize the current state of commercially available 802.11n hardware, arming you with the information you need to determine if, when, and how you want to make the move. In these slides, we will cover: - Key technologies that are new to 802.11n - The relative importance of each technology in contributing to increased performance - The current “state of the art” of commercially available 11n equipment What you will learn: - What new 11n technologies are most important to you - When to use the various 11n technologies - How to monitor and analyze WLANs – both mixed-mode and Greenfield 11n Watch the full webcast at: http://bit.ly/80211nIncreasedSpeedComplexity.TRANSCRIPT
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Jay Botelho
Director of Product Management
WildPackets
Follow me @jaybotelho
802.11n Increased Speed, Increased Complexity
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Agenda
• 802.11n – Evolution or Revolution?
• Features vs. Performance vs. Complexity
• 3-Stream – How Available Is It?
• Employing 802.11n Features
• Monitoring and Analysis in Mixed Environments
• Company Overview
• Product Line Overview
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802.11n – Evolution or Revolution?
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802.11n – Evolution vs. Revolution?
• MIMO: Multiple Input – Multiple Output
• Channel Bonding
• Aggregation and Block Acknowledgements
• Short Guard Interval (SGI)
• Beam Forming
© WildPackets, Inc. 5 802.11n – Increased Speed, Increased Complexity
Example – Purdue University
• "The management of our wireless network, when you
boil it down, is three people. It's three busy people,
but not three suicidal people." - Scott Ksander, Executive Director of Networks and Security
• 6,000 802.11n APs, 265 buildings, 10,000 users
• Using a controller-based architecture is a must
• Uses Cisco software for centralized monitoring but
requires specific trouble-shooting tools for the field
• 11n is a must – Purdue learned the hard way that
large lecture halls with 802.11bg APs could not
tolerate 600 students logging in at the same time
Source: http://searchnetworking.techtarget.com/news/article/0,289142,sid7_gci1373978,00.html
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The Real World at Liberty University
• Multi-channel, IP-based video (IPTV) over wireless
• Provide roaming students with universal access to
multi-channel video
• Delivery of 15 live TV channels
• Liberty's campus channel as well as ABC, CBS, CNN,
ESPN, FOX, NBC, and a range of other broadcasters
• Serves 46,000 local/remote students and 2,600 FTEs
• Network includes more than 770 Aruba 802.11n
access points
Source: http://www.marketwire.com/press-release/Liberty-University-Launches-Campus-Wide-Wireless-
IPTV-Using-80211n-Wi-Fi-From-Aruba-NASDAQ-ARUN-1069662.htm
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MIMO Multiple Input, Multiple Output
• Multipath reduces the
signal strength of the data
transmission
• A second antenna is used
for ―spatial diversity‖
• Multipath still exists, but it
is also leveraged to send
multiple, independent data
streams
• Essentially 4x the
throughput
TX RX
01110001010
TX RX 01110001010
10010001010
11110001010
00000001010
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Channel Bonding
• Creates a single 40 MHz channel from two adjacent
20 MHz channels ‒ More than doubles effective data rate
‒ 802.11n can use both 20 MHz or 40 MHz channels in both the
2.4 or 5 GHz band
http://wifijedi.com/2009/01/25/how-stuff-works-channel-bonding/
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Aggregation
• A-MSDU
‒ Single MAC frame, multiple PDU
(Protocol Data Units)
‒ Processed by MAC layer as single entity
‒ De-aggregation required by receiver
• A-MPDU
‒ Multiple MAC frames
‒ Each MPDU encrypted/decrypted individually
‒ Requires Block Acknowledgement
http://mnet.cs.nthu.edu.tw/paper/tmlin/050923.pdf
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Block Acknowledgements
• Borrows ―windowing‖ technique from TCP/IP
• Acknowledges multiple frames with a single ACK
• Missing frames are retransmitted
• Can significantly reduce management overhead
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Other Techniques
• Short Guard Interval (SGI) ‒ Guard interval: Amount of time between transmissions, needed
to prevent transmission overlap
‒ 802.11/a/b/g use 800 nanosecond guard interval
‒ SGI reduces the guard interval to 400 nanoseconds – 11%
performance improvement
• Beam Forming ‒ Optional part of 802.11n – not widely used yet
‒ Antenna arrays used to focus signal on area where receiver is
located
‒ Transmitter must keep track of where receiver is located
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Features vs. Performance vs.
Complexity
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Performance Per Feature
• MIMO
• Channel Bonding
• Block
Acknowledgements
• Aggregation
• Short Guard
Interval
• Beam Forming
802.11n – Are You Seeing It All?
Aruba Networks, 2008
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By The Numbers
http://www.bitcricket.com/downloads/Inside%20802.11n%20Wireless%20LANs.pdf
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Down To The Details (1, 2-Stream)
MCS
index
Spatial
streams
Modulation
type
Coding
rate
Data rate (Mbit/s)
20 MHz channel 40 MHz channel
800 ns GI 400 ns GI 800 ns GI 400 ns GI
0 1 BPSK 1/2 6.50 7.20 13.50 15.00
1 1 QPSK 1/2 13.00 14.40 27.00 30.00
2 1 QPSK 3/4 19.50 21.70 40.50 45.00
3 1 16-QAM 1/2 26.00 28.90 54.00 60.00
4 1 16-QAM 3/4 39.00 43.30 81.00 90.00
5 1 64-QAM 2/3 52.00 57.80 108.00 120.00
6 1 64-QAM 3/4 58.50 65.00 121.50 135.00
7 1 64-QAM 5/6 65.00 72.20 135.00 150.00
8 2 BPSK 1/2 13.00 14.40 27.00 30.00
9 2 QPSK 1/2 26.00 28.90 54.00 60.00
10 2 QPSK 3/4 39.00 43.30 81.00 90.00
11 2 16-QAM 1/2 52.00 57.80 108.00 120.00
12 2 16-QAM 3/4 78.00 86.70 162.00 180.00
13 2 64-QAM 2/3 104.00 115.60 216.00 240.00
14 2 64-QAM 3/4 117.00 130.00 243.00 270.00
15 2 64-QAM 5/6 130.00 144.40 270.00 300.00
http://en.wikipedia.org/wiki/IEEE_802.11n-2009
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Down To The Details (3, 4-Stream)
MCS
index
Spatial
streams
Modulation
type
Coding
rate
Data rate (Mbit/s)
20 MHz channel 40 MHz channel
800 ns GI 400 ns GI 800 ns GI 400 ns GI
16 3 BPSK 1/2 19.50 21.70 40.50 45.00
17 3 QPSK 1/2 39.00 43.30 81.00 90.00
18 3 QPSK 3/4 58.50 65.00 121.50 135.00
19 3 16-QAM 1/2 78.00 86.70 162.00 180.00
20 3 16-QAM 3/4 117.00 130.70 243.00 270.00
21 3 64-QAM 2/3 156.00 173.30 324.00 360.00
22 3 64-QAM 3/4 175.50 195.00 364.50 405.00
23 3 64-QAM 5/6 195.00 216.70 405.00 450.00
24 4 BPSK 1/2 26.00 28.80 54.00 60.00
25 4 QPSK 1/2 52.00 57.60 108.00 120.00
26 4 QPSK 3/4 78.00 86.80 162.00 180.00
27 4 16-QAM 1/2 104.00 115.60 216.00 240.00
28 4 16-QAM 3/4 156.00 173.20 324.00 360.00
29 4 64-QAM 2/3 208.00 231.20 432.00 480.00
30 4 64-QAM 3/4 234.00 260.00 486.00 540.00
31 4 64-QAM 5/6 260.00 288.80 540.00 600.00
http://en.wikipedia.org/wiki/IEEE_802.11n-2009
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3-Stream – How Available Is It?
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The Secret of ―NxM‖
• Each MIMO system is defined with NxM antenna
matrix ‒ N = # of Transmit antennas
‒ M = # of Receive antennas
‒ Ex. 3x3 AP means 3 transmit and 3 receive antenna
‒ The word chain is used to define this radio/antenna combination
• Each transmit antenna can transmit a uniquely
encoded data stream called a Spatial Stream (SS) ‒ Spatial streams sometimes written as “:x”
‒ 3x3:2 == 3 TX antennas, 3 RX antennas, 2 streams
• A system with N chains can support a maximum of N
spatial steams
© WildPackets, Inc. 19 802.11n – Increased Speed, Increased Complexity
What Are All These Antennas For?
• All antennas are equal, and do the same thing ‒ All antennas transmit
‒ All antennas receive
‒ All antennas serve the same bands
• Some antennas may transmit data (streams) while
some may be used for spatial diversity
• Some vendors have separate antennas for each band ‒ 5GHz and 2.4GHz are separated
• Some vendors have dual-band antennas
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Choosing a Wireless Adapter for Capture
• Every value in ―NxM:x‖ is critical ‒ N = # of Transmit antennas = same as most capable AP
‒ M = # of Receive antennas = same as most capable AP
‒ :x = # of Streams = same as most capable AP
• A 3x3:2 wireless adapter (the most commonly
available today) CANNOT capture 3x3:3 traffic
• A 3x3:3 wireless adapter CAN capture 3x3:2 traffic
© WildPackets, Inc. 21 802.11n – Increased Speed, Increased Complexity
Availability
• Must distinguish between APs and wireless adapters
• ―NxM‖ = 3x3 is pretty easy to find ‒ Both for APs and wireless adapters
• 3x3:3 is difficult to find ‒ Look for 450 MHz throughput – not many out there
‒ APs are a bit easier to find
‒ Wireless adapters are much more difficult to find
• Form factor is also an issue ‒ PCIe cards (internal laptop adapters) will be first to market
‒ USB devices coming slowly – power is an issue in “:3” devices
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Available External Wi-Fi Adapters
3-Stream? 2
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Available APs
3-Stream? 13
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Employing 802.11n Features
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Jay’s Recommendations
802.11n Feature Greenfield
Deployment
Mixed Upgrade
2-Stream
3-Stream
40MHz (Channel Bonding) * 5 GHz Only
Aggregation (AMPDU/AMSDU) ** **
Short Guard Interval ** **
Beam Forming
* Remember, you probably have neighbors
** This may not be something you can control
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Monitoring and Analysis in
11n Environments
© WildPackets, Inc. 27 802.11n – Increased Speed, Increased Complexity
Greenfield 802.11n
• Completely understand your environment ‒ Greenfield …, really?
‒ NxM:x – both for all APs and all wireless clients
‒ Usage of channel bonding, aggregation, etc.
• Assess availability of hardware available for wireless
data capture ‒ Must cover cross-section of AP and client NxM:x
‒ Sensitivity of wireless adapters used for capture
‒ External antenna connections are beneficial
• Choose data capture parameters that match your
environment
© WildPackets, Inc. 28 802.11n – Increased Speed, Increased Complexity
Mixed Environments
• Completely understand your environment ‒ Greenfield …, really?
‒ NxM:x – both for all APs and all wireless clients
‒ Usage of channel bonding, aggregation, etc.
• Assess availability of hardware available for wireless
data capture ‒ Must cover cross-section of AP and client NxM:x
‒ Sensitivity of wireless adapters used for capture
‒ External antenna connections are beneficial
• Choose data capture parameters that match your
environment
© WildPackets, Inc. 29 802.11n – Increased Speed, Increased Complexity
Monitoring, Analyzing, Troubleshooting 11n
• Mixed modes
© WildPackets, Inc. 30 802.11n – Increased Speed, Increased Complexity
Monitoring, Analyzing, Troubleshooting 11n
• Mixed modes
• Greater throughput
stresses wireless
analysis solutions
© WildPackets, Inc. 31 802.11n – Increased Speed, Increased Complexity
Monitoring, Analyzing, Troubleshooting 11n
• Mixed modes
• Greater throughput
stresses wireless
analysis solutions
• New applications –
it’s a platform
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Multi-Channel Analysis
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Wireless Roaming
• Campus-wide deployments
imply frequent roaming
• Roaming is the cause of many
wireless issues
• Voice and video are especially
sensitive
• Roaming analysis requires
detailed and accurate
measurements from many
perspectives
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Wired and Wireless
• Security protocols and policy
• Rogue APs and clients
• Ad-hoc networks
• Wireless security attacks
• QoS configuration and use
• Signal strength
• Dropped packets and retries
• Tracking wireless packets onto the
wired network
• QoS configuration and use
• VPN/MPLS
• Application vs. network latency
Access
Point Router
Air-link
Private
Network
or the
Internet
Auth
Server
Ethernet Ethernet
WLAN
Controller
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Company Overview
© WildPackets, Inc. 36 802.11n – Increased Speed, Increased Complexity
Corporate Background
• Experts in network monitoring, analysis, and troubleshooting
‒ Founded: 1990 / Headquarters: Walnut Creek, CA
‒ Offices throughout the US, EMEA, and APAC
• Our customers are leading edge organizations
‒ Mid-market, and enterprise lines of business
‒ Financial, manufacturing, ISPs, major federal agencies,
state and local governments, and universities
‒ Over 7,000 customers / 60+ countries / 80% of Fortune 1,000
• Award-winning solutions that improve network performance
‒ Internet Telephony, Network Magazine, Network Computing Awards
‒ United States Patent 5,787,253 issued July 28, 1998 • Different approach to maintaining availability of network services
© WildPackets, Inc. 37 802.11n – Increased Speed, Increased Complexity
Real-World Deployments
Education
Health Care / Retail
Financial
Telecom
Government
Technology
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Product Line Overview
© WildPackets, Inc. 40 802.11n – Increased Speed, Increased Complexity
OmniPeek/Compass Enterprise Packet Capture, Decode and Analysis
• 10/100/1000 Ethernet, Wireless, WAN, 10G
• Portable capture and OmniEngine console
• VoIP analysis and call playback
Omnipliance / TimeLine Distributed Enterprise Network Forensics
• Packet capture and real-time analysis
• Stream-to-disk for forensics analysis
• Integrated OmniAdapter network analysis cards
WatchPoint Centralized Enterprise Network Monitoring Appliance
• Aggregation and graphical display of network data
• WildPackets OmniEngines
• NetFlow and sFlow
Product Line Overview
© WildPackets, Inc. 41 802.11n – Increased Speed, Increased Complexity
OmniPeek Network Analyzer
• OmniEngine Manager
– Connect and configure distributed OmniEngines/Omnipliances
• Comprehensive dashboards present network traffic in real-time
– Vital statistics and graphs display trends on network and application
performance
– Visual peer-map shows conversations and protocols
– Intuitive drill-down for root-cause analysis of performance bottlenecks
• Visual Expert diagnosis speeds problem resolution
– Packet and Payload visualizers provide business-centric views
• Automated analytics and problem detection 24/7
– Easily create filters, triggers, scripting, advanced alarms and alerts
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Omnipliance Network Recorders
• Captures and analyzes all network traffic 24x7
– Runs our OmniEngine software probe
– Generates vital statistics on network and application performance
– Intuitive root-cause analysis of performance bottlenecks
• Expert analysis speeds problem resolution
– Fault analysis, statistical analysis, and independent notification
• Multiple Issue Digital Forensics
– Real-time and post capture data mining for compliance and troubleshooting
• Intelligent data transport
– Network data analyzed locally
– Detailed analysis passed to OmniPeek on demand
– Summary statistics sent to WatchPoint for long term trending and reporting
– Efficient use of network bandwidth
• User-Extensible Platform
– Plug-in architecture and SDK
© WildPackets, Inc. 43 802.11n – Increased Speed, Increased Complexity
Omnipliance Network Recorders Price/performance solutions for every application
Portable Edge Core
Ruggedized
Troubleshooting
Small Networks
Remote Offices
Datacenter Workhorse
Easily Expandable
Aluminum chassis / 17” LCD 1U rack mountable chassis 3U rack mountable chassis
Quad-Core Xeon 2.5GHz Quad-Core Intel Xeon
X3460 2.80Ghz
Two Quad-Core Intel Xeon
E5530 2.4Ghz
4GB RAM 4GB RAM 6GB RAM
2 PCI-E Slots 2 PCI-E Slots 4 PCI-E Slots
2 Built-in Ethernet Ports 2 Built-in Ethernet Ports 2 Built-in Ethernet Ports
500GB and 2.5TB SATA
storage capacity
1TB SATA storage capacity 2TB SATA storage capacity
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TimeLine
• Fastest network recording and real-time statistical
display — simultaneously ‒ 11.7Gbps sustained capture with zero packet loss
‒ Network statistics display in TimeLine visualization format
• Rapid, intuitive forensics search and retrieval ‒ Historical network traffic analysis and quick data rewinding
‒ Several pre-defined forensics search templates making
searches easy and fast
• A natural extension to the WildPackets product line
• Turnkey bundled solution ‒ Appliance + OmniEngine, OmniAdapter, OmniPeek Connect
© WildPackets, Inc. 45 802.11n – Increased Speed, Increased Complexity
TimeLine For the most demanding network analysis tasks
TimeLine
10g Network Forensics
3U rack mountable chassis
Two Quad-Core Intel Xeon 5560 2.8Ghz
18GB RAM
4 PCI-E Slots
2 Built-in Ethernet Ports
8/16/32TB SATA storage capacity
© WildPackets, Inc. 46 802.11n – Increased Speed, Increased Complexity
WatchPoint Centralized Monitoring for Distributed Enterprise Networks
• High-level, aggregated
view of all network
segments
– Monitor per campus, per
region, per country
• Wide range of network
data
– NetFlow, sFlow, OmniFlow
• Web-based, customizable
network dashboards
• Flexible detailed reports
• Omnipliances must be
configured for continuous
capture
© WildPackets, Inc. 47 802.11n – Increased Speed, Increased Complexity
WildPackets Key Differentiators
• Visual Expert Intelligence with Intuitive Drill-down
– Let computer do the hard work, and return results, real-time
– Packet / Payload Visualizers are faster than packet-per-packet diagnostics
– Experts and analytics can be memorized and automated
• Automated Capture Analytics
– Filters, triggers, scripting and advanced alarming system combine to provide
automated network problem detection 24x7
• Multiple Issue Network Forensics
– Can be tracked by one or more people simultaneously
– Real-time or post capture
• User-Extensible Platform
– Plug-in architecture and SDK
• Aggregated Network Views and Reporting
– NetFlow, sFlow, and OmniFlow
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Q&A
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