Pervasive Wireless LANs
Serving The Needs Of
Higher Education
Kamal Anand
VP Marketing
kamal@merunetworks.com
Company Background
 Founded in 2002
 Customers include Higher Ed, Healthcare, Retail,
Manufacturing, F500
 Deployed in over 30 Higher Education Institutions
2
Wireless LAN Evolution
Hubs, Switching to Coordination
Stand Alone
Hot-Spot
Pervasive
Number of
Clients and
Coverage
Applications
Products /
Technology
Architecture
• Voice and Data
• Business applications
• Primary connectivity
• Video emerging
• Email, Web
• Email, Web
• Bridge
• Centralized
security and
management
• High Density, QoS,
• Transparent mobility
• Multi-Services WLAN
• Wireless hub
• Minimal AP
• WLAN Switch
• Coordinated WLAN*
* Gartner’s Dulaney describes as “4th Generation
3
Enterprise WLAN Product Evolution
2000-02
1st
Generation
Stand-alone
2003-4
2004-5
2nd Generation
3rd Generation
Centralized
Coordinated
Meru
Cisco 350
Orinocco
RoamAbout
Basic
Connectivity
Stand-alone
Cisco 1200+SWAN
Symbol
Aruba, Trapeze,
Airespace …
Generation 1 +
Central Management
Security
Aggregated AP’s
Central Switch/
Appliance
4
Generation 2 +
RF Intelligence
High Density
QoS
Zero Handoff
Coordinated AP’s
Central Controller
Meru WLAN Products
Simple Deployment Architecture
 Coordinated Access Point
►
►
►
Floor 2
Air Monitor + Access Point
Application Flow Classification
Contention management
AP
 Controller
►
►
►
Meru AP
Virtual AP Floor 1
Centralized appliance for
coordination, management and
security
Built-in application
Flow-Detectors e.g.
SIP, H.323, Spectralink SVP
Platform for services:
e.g. Location Tracking
AP
Data Center
Meru Controller
5
L2 / L3
Backbone
Enterprise Scale Deployment
Central Campus
Deployment Options:

Floor 2


Meru AP
L2 LAN between AP and controller
(e.g. branch office, corp bldg)
L3 campus network between AP
and controller (e.g. campus)
L3 WAN between AP and controller
(e.g. remote office)
Remote Office
Overlay Network Leveraging:

Floor 1


Existing L2/L3 devices
Existing WAN connections
Existing WiFi clients
AP
Branch Office
Data Center
Internet
Meru Controller
Servers - Radius,
DHCP, LDAP Web
6
Pervasive WLAN Requirements
Higher-Ed is Key Example
 Deployment and RF
Intelligence
 Predictable Performance
►
Budget constraints and service
level expectations
►
Lecture halls, classrooms,
libraries, unions.
►
Data today
Voice emerging – soft phones,
Wi-Fi phones
Video – lecture content, video
presentations
in High Density
►
 Multiple Applications:
►
Data, Voice, and Video
►
 Seamless Mobility
►
 Integrated Security
►
7
Students, faculty, visitors –
constant movement
Student / faculty / guest security
Integration with network access
control
Wireless Channel Planning Problem
How should you place Access Points in order to achieve
pervasive coverage and optimum performance?
 Access Points are hubs: RF is shared medium
 Connectivity bound by physical proximity to AP
►
►
Signal strength degrades with distance
Trade-off between data rate and coverage
 Spectrum is limited (particularly in 2.4GHz band):
Capacity is bounded in space
 Interference is dictated by neighborhood of both
transmitter and receiver (i.e. transmit power control is
necessary but not sufficient)
Goal is to deploy APs in a way that minimizes
contention for shared spectrum across APs
8
RF Design and Planning Myth
By doing channel planning and
deploying on the three non-overlapping
channels you can avoid co-channel
interference
9
Deployment of APs in Pervasive
WLAN: Co-Channel Interference
Signal
Strength
There are 3 nonoverlapping
channels in 2.4GHz
(Ch 1, 6, 11)
x
x
-68dBm
x
x
-95dBm
54Mbps
1Mbps
x
x
10
Distance
Meru Coordinated WLAN
Architecture
 APs act as a coordinated system of
antennas rather than each AP
acting as an individual wireless hub
►
►
All APs on the same channel have the same
BSSID (wireless MAC address)
Client only sees only one AP on a channel
Benefits:
 Minimum RF Planning
 Handoff totally transparent to clients
 Load balancing transparent to clients
 Ok to over-deploy APs for redundancy
and rogue detection
11
Physical WLAN
Infrastructure
Client’s View of
Meru WLAN
Meru Simplifies Deployment
Meru’s RF Planning Framework
 Automatic channel planning
 Automatic power control
 Coordination of channel access across APs
 Virtualization of a “cell”
 Global optimization of settings based on
environment goals
12
MAC problem: Trade-off between
Throughput and Density
 CSMA throughput degrades
with contention
11
Baseband + Protocol Overhead
8
(Mbps)
Total Bandwidth at Peak
Peak Aggregate Throughput
in Single Cell Environment
 Contention loss is more severe
in 802.11 than Ethernet
 Cannot detect collisions
directly
 Backoff scheme trades off
fairness for scale
5
Contention
Loss
1
802.11 MAC
Performance
3
20-25
Number of Simultaneous Contenders
13
Meru Air Traffic Control Technology
Predictable Performance with Density
Active Users Per AP
100+
11
8
(Mbps)
Total Bandwidth at Peak
Peak Aggregate Throughput
Meru AP
Performance
5
Contention
Loss
1
20-25
Today’s AP
Performance
3
Today
20-25
Number of Active Users
14
Meru
Predictable and Better End User
Experience
Throughput
1 AP + 20 Clients
Throughput
1 Meru AP + 20 Clients
 Predictable, uniformly fair throughput
across all clients
15
QoS Requirements
Wired and Wireless LANs
 In order to provide Quality of Service,
the infrastructure must have the
following components:
Low delay
► Low jitter
► Low packet loss
►
 Wired LANs addressed this by utilizing
switches instead of shared medium
hubs as well as increasing bandwidth
16
QoS: Wireless Requires More
Wired Network
Sender
Wireless Network
S
S
I
I
I
Scheduling
Packets Meets
Requirements
Receiver
►
►
R
Needed:
Scheduling
+
Contention Management
R
Packet scheduling provides QoS as
duplex, switched medium
Even with the old hub architecture
collisions could be detected in realtime unlike wireless.
►
►
►
►
17
Multiple stations contend for the
same shared medium
While transmitting, sender cannot
listen at same time for collisions
Scheduling not enough for QoS
Predictable channel access is key for
jitter and QoS – typical 802.11
implementations don’t provide this
Meru Air Traffic Control
Global RF Resource
Knowledge
+
Meru QoS
Algorithms
Application Flow
Detection

Global knowledge of interference and resource
usage at AP’s including knowledge of clients
 Time-based accounting, not bandwidth-based
 Inter-cell Coordination

Deep packet inspection for understanding resource
requirements of Application (e.g. SIP/Codec)

Resource management
+
Admission Control
+
Per-flow Scheduling
+
Control Mechanisms
in 802.11 Standard

Uplink and Downlink accounting of packets /
expected packets
 Reservation-based QoS

Virtual carrier sense for uplink reservation/QoS
 Contention-free periods and contention periods.
18
Meru Air Traffic Control
Over-The-Air QoS
Over-the-air
QoS
AP
Standards-based
Over-the-air
QoS
Wired
QoS
AP
Wired
QoS
20+
Voice
Quality
MOS Score
Low
4.0+
Generic Access Point +
Standard Client
Access Point with
Over-The-Air QoS
Standard Client
Typically data and voice on
Separate channels/network
Converged Network - voice
and data on same channels
19
How Meru Over-the-Air QoS
Compares to Others
Meru
Other Approaches
Global RF Knowledge and
Inter-cell Coordination
Yes
--
Application Flow Detection
and Classification
Yes (Dynamic)
Static ESSID-based or
Filters
Yes
--
Reservation-based
True over-the air QoS
Simple Priority of
packets
Reservation-based
True over-the air QoS
--
Per-class, Per-station,
time-based fairness
FIFO or packet based
Admission Control
Downlink (AP to Client)
Uplink (Client to AP)
Fairness across clients
20
Meru Air Traffic Control Technology
Zero Handoff
Meru WLAN
Today’s WLAN
Virtual AP Architecture
BSSID = A
BSSID = M
BSSID = B
BSSID = M
00:00
01:00
100ms – 1 sec between handoff
No Handoff For Client
21
SUNY Stony Brook
Meru Customer Success Story
“
We needed a WLAN system that was
easy to deploy across many buildings
on campus, could be centrally managed
over an IP routed network, and could
implement different security policies for
different classes of users. Meru’s plug‘n-play deployment model with
centralized policies and control, its
ability to deploy access points anywhere
on campus across IP subnets, as well
as its flexibility in supporting 64 different
ESSIDs each with a different security
policy made the system move to the top
of our evaluation list.
Mr. Richard W. Reeder, Chief
Information Officer of SUNY Stony
Brook University
22
”
Contention Management
Effortless Scalability and Deployment
Virtual AP
Student
Center
Meru Controller
 Supported over 500 users
L2/L3
Network
at the Conference on
Instructional Technologies
 With L3 mobility, extending
wireless to a new site is as
easy as plugging an AP
into any data jack on the
campus
Dormitories
 Supports any user with a
standard 802.11device
without any client software
23
Computer Lab
Library
Key Benefits of Meru for Pervasive
WLANs
1.
Minimal RF Planning: Meru virtually eliminates RF
planning and manages co-channel interference
2.
Highly Scalable: Meru supports extremely high user
densities with any dynamic mix of voice and data
3.
Handoff: Meru provides for client handoff without any
loss for higher quality voice and data applications
4.
Convergence: Meru allows you to deploy WLANs with
voice and data on the same Access Points, in multi-cell
networks.
5.
True b/g Performance: Meru gives g clients full rate
performance in mixed b/g networks
24
Thank You
Serving The Needs Of
Higher Education
Kamal Anand
VP Marketing
kamal@merunetworks.com