Download pdf - 802.11n - Increased Speed Increased Complexity

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Jay Botelho

Director of Product Management

WildPackets

[email protected]

Follow me @jaybotelho

802.11n Increased Speed, Increased Complexity

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© WildPackets, Inc. 2 802.11n – Increased Speed, Increased Complexity

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


802.11n – Evolution or Revolution?


802.11n – Evolution vs. Revolution?

• MIMO: Multiple Input – Multiple Output

• Channel Bonding

• Aggregation and Block Acknowledgements

• Short Guard Interval (SGI)

• Beam Forming


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


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


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


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/


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


Block Acknowledgements

• Borrows ―windowing‖ technique from TCP/IP

• Acknowledges multiple frames with a single ACK

• Missing frames are retransmitted

• Can significantly reduce management overhead


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


Features vs. Performance vs.

Complexity


Performance Per Feature

• MIMO

• Channel Bonding

• Block

Acknowledgements

• Aggregation

• Short Guard

Interval

• Beam Forming

802.11n – Are You Seeing It All?

Aruba Networks, 2008

http://www.wildpackets.com/mypeek_registration/webcast-27





By The Numbers

http://www.bitcricket.com/downloads/Inside%20802.11n%20Wireless%20LANs.pdf


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

http://en.wikipedia.org/wiki/Code_rate



http://en.wikipedia.org/wiki/Guard_interval




http://en.wikipedia.org/wiki/BPSK

http://en.wikipedia.org/wiki/QPSK


http://en.wikipedia.org/wiki/QAM














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

























3-Stream – How Available Is It?


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


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


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


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


Available External Wi-Fi Adapters

3-Stream? 2


Available APs

3-Stream? 13


Employing 802.11n Features


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


Monitoring and Analysis in

11n Environments


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


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


Monitoring, Analyzing, Troubleshooting 11n

• Mixed modes



• Mixed modes

• Greater throughput

stresses wireless

analysis solutions



• Mixed modes

• Greater throughput

stresses wireless

analysis solutions

• New applications –

it’s a platform


Multi-Channel Analysis


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


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


Company Overview


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


Real-World Deployments

Education

Health Care / Retail

Financial

Telecom

Government

Technology

http://www.fbiband.com/

http://www.dea.gov/


Product Line Overview


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


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


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


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


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


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


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 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


Q&A

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#wp_80211n with any questions, comments, or feedback.

Follow us @wildpackets

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Thank You!

WildPackets, Inc.

1340 Treat Boulevard, Suite 500

Walnut Creek, CA 94597

(925) 937-3200