2. Towards a modernisation of CERN’s telephony infrastructure 26/03/2015 2 Francisco VALENTÍN VINAGRERO Anthony HESNAUX IT-CS-CS

3. Index Today’s network Project goals A glimpse of SIP BRAINS 26/03/2015 3

4. Today’s network 26/03/2015 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

5. Today’s network 26/03/2015 5 Manages 12K fixed lines + 6K mobile phones (Closed User Group) *Source: comstat.cern.ch Operator 3 CERN’s national mobile operator network CERN’s CUG CERN’s fixed network Non CERN phone user Operator 2 Operator 1

6. Today’s network 26/03/2015 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

7. Today’s network 26/03/2015 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

8. 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

9. Project goals 26/03/2015 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

10. A glimpse of SIP 26/03/2015 10 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

11. A glimpse of SIP 26/03/2015 11 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

12. 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 26/03/2015 12 IP Network

13. A glimpse of SIP 26/03/2015 13 SIP in action SIP ENDPOINT 1 SIP ENDPOINT 2 I NVITE From: sip:user1@domain.comsip:user1@domain.com To: sip:user2@domain.comsip:user2@domain.com Cseq: 1 INVITE SDP OFFER in the body 100 T RYING Transaction 183 S ESSION P ROGRESS 200 OK From: sip:user1@domain.comsip:user1@domain.com To: sip:user2@domain.comsip:user2@domain.com Cseq: 1 INVITE SDP ANSWER in the body M EDIA SESSION (RTP) ACK

14. A glimpse of SIP 26/03/2015 14 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

15. Center of all routing decissions for all real-time media sessions. SIP transaction-aware redirect server BRAINS 26/03/2015 15 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 oîte pour R eduire l’ A lcatel-PBX et I ntroduire des N ouveaux S ervices B ox for R educing the A lcatel-PBX and I ntroducing N ew S ervices

16. 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 BRAINS 26/03/2015 16

17. BRAINS 26/03/2015 17 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

18. Summary 26/03/2015 18 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

19. Thank you! 26/03/2015 19 Questions?