session management in an enterprise comunication ... - Genband

SESSION MANAGEMENT IN AN
ENTERPRISE COMUNICATION NETWORK
April 2012

SESSION MANAGEMENT IN AN ENTERPRISE COMUNICATION NETWORK
Table of Contents
Session Management in an Enterprise Communication Network...................... 1
Introduction................................................................................................................. 3
Session Management Challenges................................................................................... 3
GENBAND Session Management Solution...................................................................... 4
GENiUS IMS VoLTE Solution.......................................................................................... 5
GENBAND Real Time Session Management (RSM)........................................................... 7
Summary.................................................................................................................... 10
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SESSION MANAGEMENT IN AN ENTERPRISE COMUNICATION NETWORK
Introduction
Enterprise Chief Information Officers (CIOs) are increasingly
aware that growing demand for information and collaboration
at anytime, from anywhere is placing enormous burden
on network infrastructure. What was once a secure voice
network is now becoming a converged voice/data network
supporting multiple IP interfaces and services. CIOs are
pushed to their limits when confronted with questions such as:
• How to support a multi-vendor network and guarantee
interoperability
• How to securely convert their existing public voice access
from costly PRI trunks to inexpensive IP trunks
• How to guarantee quality voice, video and multimedia
services on a common IP infrastructure
• How to introduce new SIP services into the network without
affecting existing infrastructure
• How to meet important E911 and CALEA requirements
with the new VoIP network
Enterprises need to harness the flexibility of the converged
IP network to deliver voice and multimedia services but must
do so without creating complex overlays for each specific
service. Such convergence naturally brings to the forefront
challenges of ensuring network security and service visibility.
Clear demarcation of enterprise and service provider
networks is mandatory to manage services across the demarcation
and accounting for resource usage. The need for
visibility into the behavior of the network, the user, and the
performance of the services carried over a converged IP infrastructure
supersedes traditional Time Division Multiplex (TDM)
network management approaches. The emphasis becomes
more on gaining visibility and control over the individual
multimedia sessions that ride over the IP infrastructure.
While IP networks provide many capabilities to define Virtual
Private Networks (VPNs) and prioritize different multimedia
traffic, they are not designed to be session-aware and they
provide few capabilities to manage and control end-user
sessions; a session being the IP-equivalent of a phone call. To
illustrate this key point, many times users complain about call
quality across a voice over IP (VoIP) enterprise network while
the IP/MPLS network layer is working properly. This is a void
in current IP network solutions and has the potential to impact
converged IP-PBX installations.
GENBAND’s session management solution complements
enterprise routers, switches, IP PBXs and application servers,
delivering the information and control necessary to guarantee
quality sessions and services while customers realize both operational
and capital expense savings. This paper discusses
GENBAND’s unique approach to session management that
enables enterprises to set up, secure, monitor, manage and
account for IP-based sessions, both Session Initiated Protocol
(SIP) and H.323.
GENBAND’s solution enables network administrators to
• Establish Public Switched Telephone Network (PSTN)
like the granular control required for centralized session
management, monitoring and accounting in a highly
distributed converged IP network
• Architect real-time dynamic policy based control of the
end-to-end performance of each session
• Flexibly meet enterprise service requirements without
building separate overlay networks
• Cost-effectively operate a converged communication
network for the delivery of real-time IP services
Session Management Challenges
In the converged rich-media enterprise, service support requires
traffic management on a session-by-session
basis. Unlike the PSTN, which offers predictable resource
utilization and guaranteed service levels, the IP network is
inherently a multi-service and best-effort network. A new approach
is required to derive PSTN-like controls and real-time
service predictability. The IP-layer offers Quality of Service
(QOS) and security features such as VLAN tagging and
MPLS. However, even with these lower layer features, session
quality is not guaranteed nor reported on an individual
session basis; voice quality of a VoIP session may be poor
while the IP layer is working properly. This problem is more
apparent as IP sessions travel outside the enterprise via direct
IP trunks to the service provider. While service providers
may provide Service Level Agreements (SLA) within their own
network, SLAs are difficult to guarantee as sessions traverse
multiple and worldwide IP networks. Network administrators
require added session specific control and intelligence that
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allow them the following:
1. Dynamic control over the network handling of sessions
2. The ability to tailor the session support based on both
business and network constraints, and
3. The real-time end-to-end visibility of the sessions, service
and network behaviors for usage accounting, SLA confirmation,
business continuity and capacity planning
The network administrator’s job is complicated by the distribution
of network intelligence throughout the IP network and
the introduction of a wide variety of network elements supporting
advanced IP services. Administrators need a different
session-based approach that gives them PSTN-like control
and defuses the complexity of delivering real-time services
within a converged IP network.
GENBAND provides a session management solution that was
purpose-built to address these issues and give network administrators
the tools and statistics necessary to control service
delivery at the session layer. This system solution consists of
two components: (1) Session Border Controller (SBC) and
(3) Real-Time Session Manager (RSM). Working together,
these products provide the authoritative network probe points
and analytics to (1) collect and report session statistics, (2)
analyze the session statistics in real-time, and (3) act on the
analysis results so that sessions continue to meet user-defined
quality metrics. The next section discusses GENBAND products
and session management in further detail.
GENBAND Session Management Solution
GENBAND products are architected along three wellestablished
network layers loosely matching layers 3, 5,
and 7 of the OSI stack (refer to figure 1). This architecture
results in flexible software products that separate signaling
from media, products that can be packaged in different ways
depending on customer needs and products that meet new
IMS concepts.
At layer 3, corresponding to the transport layer, is the GEN-
BAND S3 SBC. The SBC provides IP security functionality
while processing both signaling and media. These features
include the following:
Figure 1 – The GENBAND S-Series is a family of session oriented products
each targeted to handle specific areas of session-based service delivery and
management
Signaling features:
SIP Signaling: Voice, Video, IP BPX Trunking, SIP/H.323 Interworking
function, Routing/Hunting, Call Admission Control,
SLA Policy Enforcement
Security features:
VoIP Firewall, NAT, NAT Traversal, DoS Protection, Topology
Hiding
Media features:
VLAN Tagging, 802.1p/q, QoS, •diffserve
Selective media routing with optional transcoding
Regulatory features:
E911 emergency services, Legal Intercept
The GENBAND S3 SBC is also a network probe point that
collects per-session data such as packet delay, jitter, and
lost packets. It also calculates Mean Opinion Score (MOS)
per session, reporting this information in per-session Session
Detail Records (SDRs). Per-session SDRs are unique in the industry
and one of the core components of intelligent session
management.
Next, at layer 5, the GENBAND S3 SBC provides an endto-end
view of the session. With an integrated SIP Proxy and
H.323 gatekeeper, the SBC performs registration and global
session routing from IP-PBX to SBC and between IP-PBXs.
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SESSION MANAGEMENT IN AN ENTERPRISE COMUNICATION NETWORK
However, different than a basic SIP proxy or Gatekeeper, the
S3 SBC supports a multitude of enhanced routing and hunting
features that give network administrators superior control
of IP sessions. Some of those features include:
Many of these features offered by GENBAND are unique in
the industry. The S3 SBC is also used as a probe point to
generate SDRs containing session statistics such as session call
hold times and post dial delay times.
Routing Engine features:
• Port and Trunk Group level granularity for routing allows
the establishment of routing policies on an endpoint
basis down to the port level or Trunk Group level
• Flexible policy enforcement can be applied for both
incoming and outgoing calls
• GENBAND calling plans facilitate a large variety of routing
policies including time of day routing, route priority
by route or endpoint and route hunting
• Sophisticated call treatment of the called and calling
numbers enables applications such as permissive dialing
and adapt call requests to the unique requirements of
terminating gateways
• Support for over 2 million routes per system
• Comprehensive SDRs that capture over ninety (90) per
session performance statistics
Dynamic Call Hunting features
• On a failed egress call attempt, the next destination
endpoint to be selected is one which is the best of the
remaining set of endpoints which can route that call.
• Up to 16 route hunts or route advances can be set up on
the system.
• Call hunting is enabled globally for the system or on
a per source endpoint basis. The configuration on the
source endpoint overrides the global system setting.
• Call hunting is dynamically disabled whenever the destination
endpoint sends media in its Progress Message
indication.
• Both SIP and H.323 calls are subject to hunting. Whenever
the S3 SBC forwards media, hunting is disabled for
that call. Every route hunt generates a SDR. The SDRs
are linked by a common callid.
• The S3 SBC is compliant with the Internet Draft on SIP to
ISDN/Q.931 release cause mappings.
Finally, there is the application layer session manager known
as the GENView RSM. The RSM collects statistics from the
SBC(s), for example packet delays, jitter, lost packets, MOS
score, session call hold times, post dial delay times, and
malformed SIP message statistics. The RSM pulls these statistics
from SDRs and first reports them to the network operator to
help them manage their network. Second, the RSM analyzes
the data against metrics defined per subscriber, per session
and per application to determine if there are network problems,
for example MOS metrics drop below acceptable levels
or call duration drops below thresholds - both indicators that
there are session problems. Third, if problems are found, the
RSM immediately notifies an operator via email or page.
Finally, the GENView RSM will automatically correct problems
by generating new route paths and updating SBCs with the
new policy
information. This patent-pending feedback loop, known as the
Dynamic Policy Management (DPM), between the RSM and
the SBCs completes the session management solution; the RSM
capitalizes on the SBC session insight to dynamically control
sessions depending upon current network conditions.
GENiUS IMS VoLTE Solution
The GENBAND intelligent session management system complements
other IP-PBX offerings by addressing, for example,
multi-vendor issues, multi-protocol issues, QoS, security, and
reliability concerns. Figure 2 depicts a typical large distributed
IP-based enterprise communication network consisting
of IP-PBXs from multiple vendors, both TDM and IP gateways
to thes service provider and multiple IP- based applications
such as conferencing and unified messaging. Also included
are GENBAND session management components including a
standalone SBC, collocated SBC and a RSM:
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SESSION MANAGEMENT IN AN ENTERPRISE COMUNICATION NETWORK
later matched to SLA commitments by the service provider. In
addition, the S3 SBC can be configured to trickle calls back
through SIP Trunk 1 until QOS is improved at which time it
will switch back to normal static routing rules. All of these actions
are automatic and controlled by user-configured policies.
It is a simple example but it presents the basics of intelligent
session management and differentiation offered with the
GENBAND solution. Many service provider and enterprise
customers have already began implementing a session
management system and are reporting numerous benefits
both inside the enterprise and between enterprise and service
provider. Some of these benefits are listed below:
Figure 2 - GENBAND S-Series SBC Solution Offering
The standalone S3 SBC delivers industry-leading functionality,
having been awarded security and feature awards from
several independent test houses including Network World’s
Clear Choice Award. Even further value is delivered when the
SBC advanced routing capabilities and session management
capabilities of the RSM are introduced. The example illustrates
how GENBAND components provide direct IP connectivity
between the enterprises, consumers, and VoIP service
providers via SIP or H.323 trunking.
Session Management Example: Assume the enterprise
in Figure 2 has configured the SBC so that time-of-day policy,
location-based policy and least cost routing policy dictates
to use SIP Trunk 1 for all outgoing calls. VoIP sessions will be
completed through the GENBAND S3 SBC and statistics are
collected after each call. Suddenly, calls through SIP Trunk
1 receive low MOS scores indicating a quality of service
challenge deep within the service provider’s network. This
results in user complaints and potentially lost revenue. With
GENBAND’s session management SBC and the RSM analytics,
this condition is identified very quickly by the RSM, which
triggers several events. First, it notifies the SBC to override
static routing rules so that future sessions are routed to the
alternate SIP Trunk 2 - resulting in higher call completions
and fewer complaints. Second, the RSM notifies network
operations personnel via email or phone that a problem has
been encountered. Third, it generates reports that can be
Session management benefits within the enterprise
• Centralized inter-PBX dial plan management
• Multi-vendor IP-PBX interoperability
• SIP and H.323 protocol interworking
• SDR aggregation
• Proactive voice quality monitoring / reporting / notification
• Least cost routing for intra-enterprise calling (on-net
versus intra-state versus inter-state)
• Policy decision-based routing – LCR Override
• Centralized Call Admission Control
Session management benefits between enterprise
and service provider:
• End-to-end SLA quality assurance
• Least cost routing (multiple SP access and multiple SPs)
• Policy decision-based routing – LCR Override
• Take-back and transfer within the enterprise, carrier
agnostic
• Protocol interworking (SIP to H.323) between service
provider and enterprise
• SIP normalization between service providers
• Secure network edge, especially for carrier provided
VPN
These same customers are reporting significant operational
and capital expenditure benefits when adding session
management to their IP-BPX enterprise. Some of the savings
include the following:
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SESSION MANAGEMENT IN AN ENTERPRISE COMUNICATION NETWORK
Operation Expenditure Benefits:
• Enables lower carrier access and feature rates
• Network-wide least cost routing reduces telephony
expenses
• Provides evidence for SLAs with service provider (loss
recovery)
• Reduces labor required to support configuration and
maintenance of dial plans across PBXs
• Reduces cost of SDR collection/aggregation
• Enables carrier bypass through enterprise-to-enterprise
VoIP peering
Capital Expenditure Benefits:
• Leverages existing investments through protocol and
vendor interworking
• Avoids over-provisioning to ensure network supports realtime
data
As previously discussed, GENBAND’s intelligent session management
system complements IP-PBX offerings and delivers
significant customer benefits that are unique in the industry.
Session management differentiates an enterprise bid from
competitive bids.
GENView Real-Time Session Management (RSM)
The GENView RSM complements the GENBAND S3 SBC by
providing automatic feedback of network behavior, SLA or
threshold checking and the dynamic adjustment of session
devices and interconnects. The feedback provides enterprises
with a highly predictive, scalable service architecture for session
based applications. In addition, the RSM is designed to
provide the network administrators with a single point from
which they control and assess the performance of sessions
traversing the GENBAND SBC.
RSM Architecture
The RSM runs on a standards-based Intel hardware platform
hosting a carrier-grade Linux-based operating system. The
GENView RSM architecture is illustrated in Figure 3. The RSM
and SBC run on separate hardware platforms.
An RSM Agent component runs on the SBC platform, which
provides the required information and interface to the RSM.
The RSM Agent implements several logical modules including
Figure 3 - Architecture illustrates the interaction between the GENBAND
Real-time SessionManager (RSM) and the S-Series SBC
the SDR server, J server Interface and logPP in the SBC. The
SDR server reads the SDRS files created by the SBC and
delivers them to the RSM server using standard HTTP or
HTTPS. The delivery of SDRs is via POST mechanisms with
up to 2500 SDRs per second supported. Optionally, the SBC
can be configured to stream SDRs to third-party databases.
Similarly, log files gathered at the SBC may be forwarded
to the RSM server using logPP agent component, for further
analysis. This enables service operators to react to alarms
and events indicating threshold crossings in either the session
performance or health of the session elements. The RSM may
be set up to dynamically update route tables at the SBC when
reacting to session status and health.
The RSM is supported by a web-based RSM client. Additionally,
the RSM web-services API provides northbound interface
for programmatic flow-through provisioning. Service operators
and NOC personnel can use their browsers to remotely
manage the GENBAND entities or integrate with existing
management tools via the web services API.
The GENBAND RSM supports these session management
tasks:
• Policy and route management for Call Admission Control
(CAC)
• Quality of Service and Service Level Management
• Service visibility and performance records
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• Alarms and Events affecting the service
• Centralized Provisioning and maintenance
• Generating reports for business and network planning
tasks
• SDR management
The GENView RSM also includes the following task-specific
modules:
• Route Analysis Module (RAM) – the RAM running
on the GENView RSM server processes SDRs in real-time
from multiple SBC platforms and is used to determine
QoS. This is the fundamental component by which
the RSM Agent communicates with the SBC. The RAM
provides a basic set of engineering reports including the
Answer Seizure Ratio (ASR), listing of 200 most recent
calls, and enables custom reports to be specified.
• Events and Statistics Module (ESM) – the ESM
facilitates alarming which can be syslog based or SDR
based. SBC log files are parsed for specific error codes
to trigger alarms. Similarly, SDR information (e.g. error
response, ASR threshold, total number of minutes, etc.) is
used to assess event and alarm generation. Action taken
includes logging the error to a file, generating an email
to the network administrator, or blocking a particular
endpoint via the Adaptive Routing Module.
• Adaptive Routing Module (ARM) – the ARM
provides a set of actions to change the route table configuration
on the SBC. The ARM provides a mechanism
to disable calls at endpoint ingress or egress based on
alarm conditions and network capacity states.
• Business Analysis Module (BAM) – the BAM
processes SDRs from the RSM database to produce ondemand
business reports. These include usage and cost
by route, sector, etc. The RSM provides hooks to external
billing and accounting systems via its Web Services
(WSDL) interface.
• Web Interface Module (WIM) – the WIM provides
user access via a web interface for which the user is
authorized. Subscribers may be set up with portal access
for self-care purposes, controlled and secure in their
group or department. In cases where the RSM is shared
between multiple groups, known as partitioning, the
WIM restricts user views to their respective partitions.
Note that there is no limit to the number of user per
partition or number of access lists.
• Least Cost Routing Module (LCR) – LCR generates
routing rules based on BAM rating information. The LCRgenerated
routes are then used to reconfigure the route
tables in the SBC to effect the required changes.
• Third Party SDR Support Module (TCS) – the TCS
enables importing of third-party SDRs into the RSM for
reporting/rating and exporting to third-party database
directly from the RSM. Under partitioned conditions, only
SDRs that belong to that partition are streamed.
RSM Reports
The reports generated by the GENView RSM enable network
administrators to monitor system activity in real-time for technical
and business purposes. Engineering reports display the ASR in
various formats, or a list of the last 200 calls can be displayed.
Up to 11 types of reports can be generated which are colorcoded
based upon ASR percentages, and a graph generated
of ASR against time. Calls are grouped and color-coded into
abandoned, busy, error or normal status categories with each
individual call and detailed SDR information available. The
report provides operational staff insight into network health and
the ability to analyze issues on a call-by-call basis. Reports can
also be filtered based upon parameters such as the SBC host
platform, start date, end date, source ID and destination ID. The
report can be set to periodically update and display via the
web interface. An example engineering report generated by the
GENView RSM is highlighted below:
Figure 4 - GENView RSM Engineering Report graphically presents the quality
of the services and other performance metrics
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The RSM system can also be used to generate up to 44
unique business reports. This feature comprises11 filters such
as Region, Customer, Supplier and various source/destination
filters each of which support the following four sort criteria:
Calls, Minutes, Revenue and Profit. An example business
report generated by the GENView RSM is highlighted below:
• Generate SNMP Trap – sends a SNMP with textual
alarm name and description to defined IP address
• Block – can be used to block all endpoint calls or set a
value to trickle calls
• Modify Endpoint Priority - can be used to change the
priority of an endpoint
• Modify Route Priority - can be used to change the priority
of a route
• Execute Script – can execute an external script file which
can be used to extend the RSM capabilities
• Log – can be used to log to Syslog or local file
• Mail – establish which email addresses should receive
specific subject-related emails
• Unblock – this restores the max calls configuration to an
endpoint
Figure 5 - GENView RSM Business Report includes analysis of the cost of carrying
the session to ensure the service operates within the business
specified constraints
RSM Alarms
The GENView RSM enables network administrators to set
specific conditions under which alarms are triggered and define
system behavior under these conditions. The RSM can be
configured to detect alarms from either system level log files
of each SBC platform or from SDRs generated by them. The
range of SDR alarm types generated include parameters such
as local disconnect, ASR, gateway minutes, dollar amount,
average request rate, average call duration, post dial delay,
low voice quality, high packet loss and jitter. All alarms can
have two sets of actions assigned, the first set of actions, or
ON-Trigger, are performed when the trigger condition is met,
for example ASR < 50%. When the trigger condition is
reset, e.g. ASR > 50%, the OFF-Trigger actions are performed.
Alarms can be based on time-of-day, system load,
region, customer, supplier or endpoint providing a flexible
environment for event detection and triggering. Alarms and
events may be associated with a range of different actions,
such as:
Figure 6 - CDR, Log, and SNMP Alarm Viewing Example
The alarm capabilities of the GENView RSM provide network
administrators with an end-to-end view into network health,
allowing automation of responses to performance changes
in the network. This enables administrators to take corrective
action for degradation in QoS thereby improving the overall
user experience.
RSM Provisioning
The provisioning support included in the RSM simplifies the
management of GENBAND endpoints, routes, calling plans
as well as rating information. For example, it enables an
administrator to configure comprehensive rating information
such as minimum duration, billing increment, and connection
charge, which can be date/time activated allowing mechanisms
such as off-peak and on-peak rates to be applied
for a given route. This information can be provisioned manually
through the web interface or by importing an external
file defining the various data into the RSM. Based upon this
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information the RSM rates SDRs for the specified regions/
routes as they are received from the various GENBAND
S-Series SBCs in the network.
Using the provisioned rating information the GENView RSM
generates a LCR report displaying routes prioritized by the
order of least cost. The priority of routes can be manually
modified and imported directly to the GENBAND SBC to
update routing criteria within the network. In
addition the RSM system is also capable of generating Maximum
Profit Routing (MPR) reports to determine which traffic
routes generate the highest revenues.
The GENBAND intelligent session management system
addresses key issues and is coupled with the most comprehensive
set of reporting capabilities available; the system
provides a visibly differentiated approach to managing a
converged network. This empowers the CIO and IT group
to deliver quality services to end-users and enables them to
introduce new converged services that improve overall
productivity.
The GENBAND RSM also provides administrators with the
capability to partition the RSM and SBC data into separate
logical entities. Up to 64 unique partitions are supported with
multiple users with custom defined capabilities and privileges
allowed. The partitioning allows administrators to use the
SBC in partitioned mode as multiple virtual switches – each
reporting separately per group or department.
Summary
GENBAND has pioneered the transformation of carrier VoIP
peering by providing network edge intelligence that ensures
PSTN-like quality and reliability for VoIP calls. Carriers using
GENBAND’s solutions have reported tripling their service
revenue and improving customer satisfaction over the
course of only a few months. GENBAND’s rich experience
in developing intelligent VoIP solutions is now being applied
to the unique requirements of the enterprise. GENBAND’s
solutions, with minimal investment and minimal infrastructure
change, allow the enterprise to:
• Receive immediate visibility and control of the real-time
VoIP applications across the enterprise network
• Seamlessly interoperate multi-vendor and multi-protocol
VoIP equipment
• Add new converged applications tailored to internal
employees, customers, and partner profiles
• Reduce PSTN toll charges by intelligently routing both
off-net local and long distance calls efficiently over the IP
network
• Enable SIP trunking between the enterprise and service
provider, taking advantage of lower tariffs and a richmedia
capable interface
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