Transcript HEPIX2015_TELEPHONY_EVOLUTIONx

Towards a modernisation of CERN’s
telephony infrastructure
Francisco VALENTÍN VINAGRERO
Anthony HESNAUX
IT-CS-CS
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Index
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•
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Today’s network
Project goals
A glimpse of SIP
BRAINS
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Today’s network
Alcatel PABX OmniPCX Enterprise
• Hybrid circuit switched – IP technology
• Geographically distributed – 4 nodes in 17 sites
• Monolithic design
• Add-ons for value-added services
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Today’s network
Manages 12K fixed lines + 6K mobile phones (Closed User Group)
CERN’s fixed
network
CERN’s
CUG
Operator 3
Operator 2
CERN’s national mobile
operator network
*Source: comstat.cern.ch
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Operator 1
Non CERN
phone user
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Today’s network
• Least Cost Routing (LCR) for outgoing calls
• Worldwide numbering plan with 800 destinations
• Local extensions with different external access rights
• Around 5M calls/year
Internal
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Today’s network
• Critical and safety services
• Switchboard
• Call Centers: Fire Brigade, CCC, Service Desk, IT Helpdesk
• TETRA interconnection
• Special analog lines: Red Phones & Lift Phones
• Integration with Mobile Telephony – CUG
• Integration with Unified Communications – Lync
• Integration with conferencing systems - Vidyo
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Alcatel PABX
Value
Added
Services
Call
Centers
Call
Routing
Switch
board
Dial Plan
management
Billing
Alarm
mgmt
Access
Rights
SOAP
API
Least Cost
Routing
Access
SIP
ISDN
Traditional
Red
phones
phones
Worldwide
PSTN
networks
GSM
gateways
GSM
UMTS
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Project goals
• Replace the PBX by a software-based solution
• Hardware/license costs
• Avoid vendor lock-in
• TETRA for critical communications
• Decouple call routing function to a new entity
• Capability to support non-Lync softphones
•
Today Lync is the only option for office phones
• Use SIP trunking with the external operators
• SIP core Network
• Using open-source solutions
• Fosters the introduction of new VoIP services
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A glimpse of SIP
SESSION INITIATION PROTOCOL
Defined in 1996. RFC2543 in 1999 replaced by SIP v2 in 2002 (RFC3261)
Uses the HTTP request/response model.
• Headers
• Status codes
• Dialog vs. Transaction
• SIP URIs
SIP
Application
RTP
Presentation
Session
UDP
TCP
TLS
Transport
sip:username@host:port
Layers 1-3
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A glimpse of SIP
Voice packetization is the key enabler of VoIP.
TIME DIVISION MULTIPLEXING
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•
•
•
MANUAL SWITCHING
End-to-end physical channel reserved
Constant bandwidth
Fixed number of channels 1 E1 = 30 channels
High infrastructure costs
MECHANICAL SWITCHING
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AUTOMATIC PBX
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A glimpse of SIP
IP packetization and independent routing
IP Network
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•
•
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Fewer infrastracture costs
Packet loss and/or variable delay or Jitter
Changing packetization time and codec may help
QoS mechanisms needed
• Softphones and Softswitches – but with specific hardware for media handling
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A glimpse of SIP
SIP in action
SIP ENDPOINT 2
SIP ENDPOINT 1
INVITE
100 TRYING
Transaction
From: sip:[email protected]
To: sip:[email protected]
Cseq: 1 INVITE
SDP ANSWER in the body
From: sip:[email protected]
To: sip:[email protected]
Cseq: 1 INVITE
SDP OFFER in the body
183 SESSION PROGRESS
200 OK
ACK
MEDIA SESSION (RTP)
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A glimpse of SIP
SIP in action
SIP ENDPOINT 2
SIP ENDPOINT 1
INVITE + SDP
100 TRYING
Transaction 1
183 SESSION PROGRESS
200 OK + SDP
ACK
DIALOG
MEDIA SESSION (RTP)
State machine
Timers
Billing
BYE
Transaction 2
200 OK
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BRAINS
Boîte pour Reduire l’Alcatel-PBX et Introduire des Nouveaux Services
Box for Reducing the Alcatel-PBX and Introducing New Services
• Center of all routing decissions for all real-time media sessions.
• SIP transaction-aware redirect server
INVITE
302 REDIRECT /
401 UNATHORIZED
BRAINS
FRONT-END PROXY
SIP User and IP
based DDoS
protection
BRAINS
ROUTING ENGINE
Calling user rights
DB
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Called user location
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BRAINS
Open-source alternatives
• Call Routing Engine: Asterisk (PJSIP) vs FreeSwitch (Sofia SIP)
• Front End (Proxy): Kamailio(OpenSER) vs OpenSIPs
System architecture:
• Cluster of CentOS 7 machines (OpenStack + Puppet)
• Front end cluster reachable by incoming SIP trunks
• Routing engine with local cached database
• Provisioning and monitoring servers
• DNS load balancing + SIP Options
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BRAINS
BRAINS
FRONT-END
INVITE
FE-1
BRAINS
ROUTING
ENGINE
RE-1
PROVISIONING
SERVER
Master DB
AIS
DB
LanDB
SIP Gateway 1
DNS
SIP Gateway 2
REGISTER
FE-2
RE-2
FE-3
RE-3
SIP phone
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DB
…
…
FE-M
DB
RE-N
DB
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Summary
Progress:
• Technology review + shortlist of open source solutions
• Concept validation
• Architecture and roadmap proposal
Next steps:
• SIP trunking with external operators
• BRAINS Beta service: Q3 2015
• Key issues to be addressed:
• Evolution of Value Added Services
• Solution for special analog lines
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Thank you!
Questions?
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