Transcript 14-Sridhar%20Ramachandran

Core Session Controller
Sridhar Ramachandran
Chief Technology Officer
[email protected]
NexTone Customers
NexTone’s Session Controllers are
deployed in over 100 carrier and service provider
networks for a total capacity of over
2 BILLION minutes a month
What is a Session Controller?
Point of control for multimedia signaling and media
− Service protection
− Network isolation and insulation
Other names
− IP-IP Gateway
− Back to back gateway
− Session Border Control
− Border Session Control
Problems where VoIP has proven effective
Transport
Switching
Interconnect
− Carrier – Carrier
− Enterprise – Carrier
Applications
• Top and bottom line enhancing
• Flexibility and enforceability are key
• Control points
Growth in VoIP Peering
ITXC Carries Record Voice Call Volumes for Holidays
http://www.itxc.com/pages/press/release229.html
“In past years, our carrier customers used ITXC to complete their subscribers’ calls because our VoIP technology allowed us
to provide them high quality at low prices. Usually, the only VoIP involved was within our network. Now carriers also choose
ITXC for interconnection because they themselves are deploying VoIP equipment in their own networks or even at their
subscribers’ premises. Our technology allows these carriers to connect their VoIP networks to ours at much less cost than a
legacy PSTN interconnect and with much greater flexibility.”
In the fourth quarter of 2003, over one third of ITXC's traffic was originated or terminated through a direct VoIP interconnect
between ITXC.net® and the network of another carrier. ITXC has VoIP interconnects with over 140 carriers or service
providers in 60 countries and supports VoIP traffic exchange with a wide variety of network equipment vendor platforms
based on either Session Initiation Protocol (SIP) or H.323 call control protocol.
iBasis Posts Record VoIP Call Volume During New Year's Day
http://www.ibasis.com/news/PR2004/pr01072004.htm
"In addition to setting an overall record for traffic, we are experiencing a record volume of traffic that enters or exits the iBasis
Network as IP traffic," said Ofer Gneezy, president and CEO of iBasis. "Major carriers have been deploying VoIP
infrastructure to support both retail services and direct VoIP carrier interconnects. At the same time, new service providers are
delivering VoIP services directly to residential and business consumers. Both can realize significant cost efficiencies by
establishing direct VoIP interconnections with our proven global VoIP infrastructure.
"More than 70% of iBasis traffic either originates or terminates through our direct VoIP interconnects with service providers.
Direct VoIP interconnects require significantly less capital expense in the iBasis network than legacy TDM interconnects. In
addition, we are enabling our customers to more fully benefit from the efficiencies of VoIP and the public Internet for global
telecommunications."
VoIP Peering Requirements
− Flexibility
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Media and Signaling Routing based on trust boundaries
“Any-to-any” interworking – SIP, H.323, multiple vendor interoperability
High Performance and Scale
“On-demand” Media Processing
− Leverage and enforce existing peering agreements
• Call Admission Control
Prevent Denial of Service attacks and service abuse/theft
• Call accounting
Call Detail Record (CDR) generation and reporting
• Topology Hiding
Go across address boundaries
− Control Points
• Segmentation/classification of traffic
What are Carriers’ session control needs?
Call routing with multiple business models:
− Wholesale
− Transit
− Pre-paid
− Post-paid/retail
Service brokerage
Special applications
− Permissive dialing
Session Controller Placement
SIP Network
Core SC
Softswitch
Edge SC
PSTN
Edge SC
PSTN
Orig/Term
Edge SC
H.323 Network
Broadband
Enterprise
Peering
Broadband
NAT Traversal
Carrier
Peering
Aggregation
Edge SC
Carrier
IP
Network
Partner Carrier
IP Network
Core SC
Edge SC
Multiple interconnects between same carriers
Multi-stage and hierarchical call admission
control
Core SC maintains notion of aggregate capacity
Merits of this Approach
No “control” protocol
Call admission control based on network egress policies
Ability to add other service selection logic
− Applications
− Quality of Service demanded or provisioned
Call routing with mixed business models
− Wholesale
− Pre-paid or post-paid
− Transit
Normalized and vendor independent call routing
− SIP only
Other Advantages
Implementation flexibility
− Redirect server
− Stateful SIP proxy
− B2BUA
Core SC function can be integrated into Edge SC
Leverage TRIP (rfc 3219) and TGREP
View Edge SCs and Gateways as originators and
terminators of sessions
What about the “Softswitch”?
“Control” paradigm has limited effectiveness
− Gateway control
− Call control
Softswitch designed for a “closed” network
− MGCP/MEGACO to provide total control of internal network
How does one build a fabric of softswitches?
Summary
Session Controllers are essential for VoIP peering
Core Session Controllers provide higher level functionality,
based on SIP signaling
Thank You.
[email protected] ; +1-240-912-1301
What about the “Softswitch”?
“Control” paradigm has not proven effective
Softswitch designed for a “closed” network
− MGCP/MEGACO to provide total control of internal network
VoIP interconnects challenge the Softswitch “control” paradigm
− Interconnects = carrier peering, and MGCP/MEGACO “control” of 3rd party
−
networks not viable
SIP/H323 typically added as after-thought to interwork trusted devices
Softswitch domains (and VoIP interconnects should never be trusted)
VoIP Interconnect Solution:
− Keep SS7 and MGs at the edge of the VoIP network, Softswitch as “cluster
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−
controller” to help handle SS7/C7
Introduce Session Controllers to manage VoIP peering and interconnects
between carriers and enterprises
Overcome lower layer (Layer 2/3) IP issues call-by-call – NAT/PAT, security,
VLANs etc
Core Session Controller
Introduction
What is a session controller?
Growth in VoIP peering
Need for more control at the core
View of softswitch
Core session controller fabric