Fixed Telephony Evolution @CERN 27/2/2015 2 Francisco Valentn
Vinagrero IT-CS-CS
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Index Todays network Project goals A glimpse of SIP BRAINS
Target architecture 27/2/2015 3
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Todays network 27/2/2015 4 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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Todays network 27/2/2015 5 Manages 12K fixed lines + 6K mobile
phones (Closed User Group) *Source: comstat.cern.ch Operator 3
CERNs national mobile operator network CERNs CUG CERNs fixed
network Non CERN phone user Operator 2 Operator 1
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Todays network 27/2/2015 6 Around 5M calls/year Least Cost
Routing (LCR) for outgoing calls Worldwide numbering plan with 800
destinations Local extensions with different external access rights
Internal
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Todays network 27/2/2015 7 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 8 Value Added Services Call Routing Access
Worldwide PSTN networks GSM UMTS GSM gateways Dial Plan management
Least Cost Routing Access Rights Call Centers Switch board Billing
Alarm mgmt SOAP API SIP ISDN Red phones
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Project goals 27/2/2015 9 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 27/2/2015 10 What is SIP anyway? VoIP = SIP ??
SIP IMS Codecs SDP RTP SBCTrunking Softphone NGN WebRTC Unified
Communications OTT VoLTE Softswitch Jitter
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A glimpse of SIP 27/2/2015 11 S ESSION I NITIATION P ROTOCOL
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:username@host:port
Application Presentation Session Layers 1-3 Transport SIP RTP
UDPTCPTLS
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A glimpse of SIP 27/2/2015 12 Voice packetization is the key
enabler of VoIP. T IME D IVISION M ULTIPLEXING End-to-end physical
channel reserved Constant bandwidth Fixed number of channels 1 E1 =
30 channels High infrastructure costs M ANUAL S WITCHING M
ECHANICAL S WITCHING A UTOMATIC PBX
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IP packetization and independent routing 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 A glimpse of SIP 27/2/2015 13 IP Network
A glimpse of SIP 27/2/2015 16 SIP in action SIP ENDPOINT 1 SIP
ENDPOINT 2 I NVITE + SDP 100 T RYING Transaction 1 183 S ESSION P
ROGRESS 200 OK + SDP M EDIA SESSION (RTP) ACK BYE 200 OK
Transaction 2 DIALOG State machine Timers Billing
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Center of all routing decissions for all real-time media
sessions. SIP transaction-aware redirect server BRAINS 27/2/2015 17
BRAINS FRONT-END PROXY BRAINS ROUTING ENGINE SIP User and IP based
DDoS protection Calling user rights Called user location I NVITE
302 R EDIRECT / 401 U NATHORIZED DB B ote pour R eduire l A
lcatel-PBX et I ntroduire des N ouveaux S ervices
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The SIP dialog and media flow is not anchored to the routing
element B.R.A.I.N.S BRAINS 27/2/2015 18 SIP Gateway domain 1 SIP
Gateway domain 2 Alice Bob I NVITE sip:bob@mygateway I NVITE
sip:bob@brains 302 R EDIRECT To: sip:bob@gateway2 I NVITE
sip:bob@gateway2 200 OK INVITE sip:bob@hisIP 200 OK Media Session
(RTP)
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Open-source alternatives Call Routing Engine: Asterisk vs
FreeSwitch 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 BRAINS 27/2/2015 19
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BRAINS 27/2/2015 20 BRAINS ROUTING ENGINE DB RE-1 BRAINS
FRONT-END FE-1 FE-2 FE-3 FE-M DB RE-2 DB RE-3 DB RE-N DNS
PROVISIONING SERVER Master DB AIS LanDB SIP phone SIP Gateway 2 SIP
Gateway 1 INVITE REGISTER
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SIP trunking with external operators Will replace TDM lines
Over dedicated lines to ensure bandwidth Geographical redundancy
Also for GSM gateway Session Border Controller (SBC) needed for:
SIP header normalization Internal topology hiding Billing of
external calls Specific hardware for media handling Target
architecture 27/2/2015 21 Operators IP network CERNs IP network
BRAINS SBC CPE1 CPE2
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B.R.A.I.N.S Alcatel PABX Dial Plan management Access Rights
Least Cost Routing 22 Value Added Services Call Routing Access
Worldwide PSTN networks GSM UMTS GSM gateways Call Centers Switch
board Billing Alarm mgmt SOAP API SIP ISDN SBC SIP Gateway VoLTE,
WebRTC Red phones
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Summary 27/2/2015 23 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
