Enterprise Fixed-Mobile Convergence (eFMC)

Tech Brief |
Enterprise Fixed-Mobile
Convergence (eFMC):
Joint Solution by
Agito Networks Inc. & Aruba Networks Inc.
Gokul Rajagopalan
Executive Summary:
The gaining popularity of smartphones and the integration of Wi-Fi capabilities into these phones raises the
question of why not consolidate multiple services into a single hardware device. This is the goal of enterprise FixedMobile Convergence (eFMC) technology. The primary value of an eFMC solution is that it allows dual-mode (Wi-Fi
& cellular) capable smart-phones to assume a single identity irrespective of their mode of connectivity and
seamlessly maintain calls during transitions from one mode to another.
Aruba Networks (NASDAQ - ARUN) is a leading provider of secure enterprise mobility solutions. Aruba’s offerings
include Campus WLAN solutions based on the 802.11 a/b/g/n standards and Branch Office solutions for secure
SOHO deployments. Agito Networks is a leading provider of enterprise Fixed-Mobile Convergence (eFMC)
Aruba Networks and Agito Networks have conducted a series of interoperability tests to demonstrate the viability
and benefits of this joint solution. VoWLAN call-quality and roaming were the focus of the interoperability exercise.
The joint solution is agnostic to the cellular carrier and technology that the phone is subscribed to.
The Agito Networks eFMC solution consists of the RoamAnywhere™ Mobility Router (RAMR) deployed in the core
VoIP network and the RoamAnywhere Dialer (RAD) client installed on recommended dual-mode phones. The
solution has been verified to interoperate well with Aruba Networks WLAN infrastructure. Best results were observed
with the Nokia E71 dual-mode handsets.
The tests were performed on an Aruba production network deployed for capacity. Aruba recommends an AP every
2500-3000 sq. ft. for voice. APs were based on the legacy 802.11a/b/g and new 802.11n standards. Enterprise
grade 802.1X authentication with AES encryption was tested in addition to the less complex static-WEP and WPA2PSK mechanisms. The tests used Windows Mobile-based HTC Touch Diamond, Symbian-based Nokia E-series
phones (E71, E63, and E51) and RIM’s BlackBerry Bold 9000 dual-mode phones.
The key performance criteria examined were stationary phone call-quality, AP-AP roaming and Wi-Fi –
cellular roaming.
Call quality was judged based on subjective voice quality and specific parameters were monitored using
802.11-based packet sniffing tools.
Agito RAMR logs were also evaluated to verify Route Point triggers (for Wi-Fi to cellular handoff) were being
used in the appropriate locations.
Enterprise Fixed-Mobile Convergence (eFMC)
Aruba Networks
Aruba also offers a unique virtual branch office solution for remote teleworkers. Using RemoteAPs – the RAP2 or
RAP5, the solution allows extension of the enterprise edge to a user across any layer-3 wide area network with the
data secured using IPSec. The intermediate connectivity model is transparent to the VoWLAN client. This test
campaign also verified that the Agito eFMC solution works seamlessly on an Aruba RemoteAP backhauled over a
standard residential DSL connection.
Aruba Solution Components for eFMC
Policy Enforcement Firewall (requires Aruba PEF license)
Aruba’s ICSA-certified PEF implements per-user, role-based access controls to track specific application flows
between a Wi-Fi client and the network. This allows per-user security and per-session QoS prioritization over the air
and over the wire. Aruba’s Voice Services Module, (integrated into the PEF module starting ArubaOS 3.4.1), gives
the power to identify Session Initiation Protocol (SIP) call signaling messages. The controller uses deep-packet
inspection to identify the ports used for voice traffic and provide prioritization to voice traffic to ensure good call
quality. Aruba’s VSM also can delay ARM scanning while voice calls are active.
Adaptive Radio Management (included in ArubaOS)
ARM automatically optimizes the RF environment in the enterprise. This includes ensuring adequate capacity
(through appropriate channel assignment on all AP radios), ensuring adequate coverage (by appropriate transmit
power assignment for all AP radios), periodically scanning the RF environment and intelligent interference rejection
and avoidance. ARM also reduces congestion by separating dual-band data clients from the mostly 2.4 GHzcapable voice handsets using band-steering and other measures.
Aruba’s controller communicates with the Agito RAMR to push ARM channel / power updates using standard
SNMP. The RAMR uses this information to automatically adjust the Route Points which define handover locations
between Wi-Fi and Cellular networks.
Virtual Branch Networking (requires Aruba RemoteAP license):
Aruba’s Virtual Branch Networking technology extends the same level of network access and seamless connectivity
that a user enjoys in the enterprise, to remote locations. This mode of access requires no more than a residential
DSL connection and a remote-AP (RAP). The RAP builds a secure IPSec tunnel back to the network core. VoWLAN
handsets can associate to this SSID and register with their SIP infrastructure, just like they would when associated
to a campus AP. Zero-touch provisioning ensures ease of use for the user with minimal network administrator
Aruba Networks
Enterprise Fixed-Mobile Convergence (eFMC)
Agito Deployment Topologies:
Remote or Home Office
For remote or home offices, it is recommended to deploy the Aruba RAP-5WN or Aruba RAP-2WG access points as
show below since these will provide enterprise-grade performance and encryption of the voice and data traffic
between the remote location and enterprise office across the internet. The RAP-5WN and RAP2WG automatically
establish a VPN connection between the remote location and enterprise Aruba Controller to extend the enterprise
WLAN to remote locations for data and voice applications to provide coverage and reduced costs for mobiles.
Enterprise Fixed-Mobile Convergence (eFMC)
Aruba Networks
The Agito RoamAnywhere Mobility Router integrates with the enterprise IP PBX utilizing SIP lines (one per mobile
device) and SIP trunks. Two corporate access numbers (or DID’s) are allocated and routed from the voice gateway
to the Agito RAMR to enable enterprise dialing from the cellular network as well as handover between the Wi-Fi and
Cellular networks.
The dual-mode smartphones register over the Aruba Wi-Fi network using the SIP protocol to the Agito RAMR that
registers on behalf of the smartphone to the IP PBX. With Agito’s architecture, there is separation of control- and
data-plane signaling such that only the SIP call signaling is routed through the RAMR while the voice/RTP packets
flow directly between the smartphones, desk phones and voice gateway ensuring low delay and jitter through the
QoS-enabled network.
At each entry/exit door of the enterprise, the Agito fingerprinting process is performed once by an administrator to
define a “Route Point” that is the location where proactive handover is initiated to ensure sub-100ms handover.
For devices that do not support detection of Route Points, the RSSI-based thresholds are utilized for handover
Infrastructure Platforms tested
Aruba Networks
Enterprise Fixed-Mobile Convergence (eFMC)
Tests and Observations
Stationary phone tests:
All handsets tested had satisfactory call-quality for stationary calls. The Aruba infrastructure identifies and follows
SIP-signaling messages and assigns appropriate prioritization to the related RTP packets. If the phones are capable
of RTCP reporting, the Aruba mobility controller can also report call quality as an R-Value. The main factors that
influence voice quality are handset support for WMM, WMM Power-Save and end-to-end QoS on the infrastructure.
Wi-Fi roaming:
The phone’s WLAN capabilities working along with the Aruba system determines the efficiency of roaming between
WLAN access points. The key differences lie in handset support for features such as Opportunistic Key Caching
and the handset driver’s RSSI and packet-error rate thresholds for roaming. For example, the Nokia E71 and the
Nokia E51 have different RSSI thresholds for roaming and as a result the E71 roams earlier than the E51.
Consequently, Aruba recommends the Nokia E71, E63 or BlackBerry smartphones for optimized roaming in Agito
Networks and Aruba Networks joint deployments.
Wi-Fi- Cellular roaming:
Agito manages Wi-Fi-Cellular roaming using a combination of real-time and pre-configured metrics. In real-time, the
RAD client periodically scans the RF environment to gauge the availability and health of Wi-Fi and cell-tower
coverage and compares it with the current mode. If the client foresees significantly better call quality on the other
mode, for example when a user enters a building and Wi-Fi signal levels exceed a pre-determined threshold, it
initiates the hand-over. However, certain areas such as building exits may be known dead-zones or fade zones for
Wi-Fi for various reasons. Agito allows the administrator to create RF Route Points (created by the administrator
through the process of Fingerprinting using the RoamAnywhere Calibration software) of such locations and then
uses these Route Points to make pre-emptive handovers to avoid degradation in call quality and proactively initiate a
seamless call transfer. Agito’s RAMR gets periodic updates from the Aruba Mobility Controller on the changes to AP
channel and transmit power which is used by Agito to dynamically adjust these Route Points based on the RF
changes. Hand-outs (hand-offs from Wi-Fi to Cell) may involve short delays depending on cellular call-setup time
whereas hand-ins (Cell to Wi-Fi) are almost instantaneous. Successful hand-outs and hand-ins with minimal to no
quality degradation were verified by Aruba and Agito engineers.
Enterprise Fixed-Mobile Convergence (eFMC)
Aruba Networks
The Nokia E71 produced the best audio quality and roam-performance of all handsets tested. The Nokia E63 and
the BlackBerry Bold 9000 are comparable to the E71. The Nokia E51 had poorer Wi-Fi roaming characteristics.
Comparatively, the HTC Touch Diamond is not recommended for use at this time due to poorer measured roaming
and battery life performance.
Over time this application note will be updated as the following supported handsets (and newly released devices)
are tested. These devices are supported by Agito and expected to work but have not been qualified with the joint
solution at this time.
- BlackBerry Curve 8900
- Samsung Epix
- BlackBerry Curve 8520
- Nokia E71x
- Samsung Omnia
- Nokia N96
Salient Configuration Notes
Adaptive Radio Management (ARM):
Aruba recommends use of the following ARM features:
Single-band assignment;
VoIP-Aware Scan;
Legacy Station Workaround (for 11n-capable networks);
Min-tx-power 6;
Max-tx-power 15.
SNMP Integration:
The RAMR receives ARM updates as SNMP traps from the Aruba controller. It uses this information to update its
information base for changes to AP channel and transmit power. For this, the Aruba controller should be configured
with the Agito RAMR as an SNMP v2c Trap receiver so that the ARM updates can by reported to the Agito system.
Additionally, the steps outlined in the section titled “Integrating WLAN Controllers with the Mobility Router” of the
Agito RoamAnywhere Administrator’s Guide should be followed in order to configure the credentials (IP and SNMP
community string) of the Aruba controller so that AP channel/power/location can be automatically retrieved by the
Agito RAMR.
Aruba Networks
Enterprise Fixed-Mobile Convergence (eFMC)
Aruba recommends use of a dedicated SSID for voice handsets. The key settings for the SSID include limiting PHY
rates to the range from 6 to 24 Mbps. WPA2-AES or lesser secure methods of authentication/encryption may be
used, while use of the strongest authentication and encryption method supported by the voice device is Aruba’s
recommendation for enterprise deployments. The ‘voice’ role which is preconfigured with Aruba’s PEF may be used
to identify and tag SIP call flows for prioritization. WMM and WMM-UAPSD support must be enabled for handsets
that support both. Maximum retries should be set to 4 and maximum transmit failures should be limited to 20 since
voice packets are delay-sensitive and must be discarded when their transmission exceeds these limits. The DSCP
mapping defined for the SSID must match with the DSCP settings for the wired back-end infrastructure. 802.11k
support may be enabled if the handset supports this newer standard. In order to facilitate fingerprinting, the voice
SSID should not be hidden.
RF Fingerprinting:
Best results were observed when Route Points were created just on the inside of every building exit. Aruba and
Agito recommend the setting of route points in this manner as a deployment best practice. Please refer to the Agito
Networks Calibration User Guide for the steps required to perform the calibration of fingerprints.
For best-practice design of a Voice over WLAN network, please refer to the following documents on the Aruba
website (http://www.arubanetworks.com/technology/design_guides.php):
Campus Wireless Networks Validated Reference Design v3.3
Virtual Branch Networks Validated Reference Design v3.0RN
Optimizing Aruba WLANs for Roaming Devices v3.3
Detailed configuration instructions can be found in the ArubaOS User Guide available on the Aruba support portal
For configuration of the Agito RoamAnywhere solution, please refer to the RoamAnywhere Mobility Router
Administrator’s Guide on the Agito Networks support website – http://www.agitonetworks.com/support/
Enterprise Fixed-Mobile Convergence (eFMC)
Aruba Networks
About Aruba Networks, Inc.
People move. Networks must follow. Aruba securely delivers networks to users, wherever they
work or roam, using a combination of award-winning solutions:
Adaptive 802.11n Wi-Fi networks optimize themselves to ensure that users are always
within reach of mission-critical information. Rightsizing expensive wired LANs by replacing
them with high-speed 802.11n Wi-Fi reduces both capital and operating expenses;
Identity-based security assigns access policies to users, enforcing those policies
whenever and wherever a network is accessed;
Remote networking solutions for branch offices, fixed telecommuters, and satellite
facilities ensures uninterrupted remote access to applications;
Multi-vendor network management provides a single point of control while managing both
legacy and new wireless networks from Aruba and its competitors.
The cost, convenience, and security benefits of our secure mobility solutions are fundamentally
changing how and where we work. Listed on the NASDAQ and Russell 2000® Index, Aruba is
based in Sunnyvale, California, and has operations throughout the Americas, Europe, Middle East,
and Asia Pacific regions. To learn more, visit Aruba at http://www.arubanetworks.com. For realtime news updates follow Aruba on Twitter at http://twitter.com/ArubaNetworks.
© 2009 Aruba Networks, Inc. AirWave®, Aruba Networks®, Aruba Mobility Management System®,
Bluescanner, For Wireless That Works®, Mobile Edge Architecture, People Move. Networks Must
Follow., RFProtect, Green Island, The All-Wireless Workplace is Now Open for Business, and The
Mobile Edge Company® are trademarks of Aruba Networks, Inc. All rights reserved. All other
trademarks are the property of their respective owners.
Aruba Networks
Enterprise Fixed-Mobile Convergence (eFMC)
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