Fosdem2012 sayer-sems-sbc
- 1. SEMS SBC Stefan Sayer CEO, FRAFOS GmbH FOSDEM 2012, 05.02.2012
- 2. Contents ● SEMS project ● The flexible, open SBC ● SBC programmability 2
- 3. The SIP Express Media Server ● Media, application server from iptel.org ● Only 1 year younger than SER (*2002) ● Widely used by carriers, ITSPs, OEMs, Universities, hobbyists 3
- 4. SEMS use cases 4
- 5. SEMS: The VAS platform ● C++, Python APIs ● DSM: State charts scripting engine 5
- 6. SBCs – what? “SBCs are SIP application servers with focus on security and isolation” 6
- 7. SBCs – the need ● Security requirements are rising → Policy enforcement and control at UNI/NNI ● Topology hiding is necessary → NAT and security ● Core call controls become big and slow → Routing and service management at NNI ● SIP implementations are buggy → “SIP normalization”, translation 7
- 8. SBCs – the special case ● On signaling and media plane ● Call stateful – high requirements for availability and scalability ● Interworking with all “SIP dialects” 8
- 9. The SEMS SBC ● Widely deployed SIP technology ● Broad range of media capabilities ● Configurable transparency ● Policy programmability – “SBC platform” 9
- 10. Signaling Features ● Topology hiding ● From, To, RURI, Contact, Call-ID manipulation ● Header and message filter ● Adding headers ● Reply code translation ● SIP authentication ● SIP Session Timer, Call Timer ● Prepaid accounting 10
- 11. Media features ● RTP anchoring / media steering ● Physical network separation ● NAT traversal, symmetric RTP (comedia style) ● Codec filter ● SDP normalization 11
- 12. Flexible profile based control sbc.conf iptelecho.sbcprofile.conf load_profiles=iptelecho URI=sip:echo@iptel.org active_profile=iptelecho From=<anonymous@mynet.net> ... To=<sip:echo@iptel.org> ... SEMS SBC # # U 210.13.3.122:5080 -> 210.13.3.100:5060 U 210.13.3.100:5060 -> 213.192.59.75:5060 INVITE sip:+49123@osbc1.mynet.net SIP/2.0 INVITE sip:echo@iptel.org SIP/2.0 From: “John” <sip:+431556221@mynet.net>;tag=12 From: <anonymous@mynet.net>;tag=3213 To: “Clara” <+49123@mynet.net> To: <sip:echo@iptel.org> Call-ID: 3cde5d1a960a-dez6oz34llo4 Call-ID: y76IIPf4UD68bb ... ... ● define SBC behaviour in profiles 12
- 13. Set RURI, From, To, Call-ID ... set_fromto.sbcprofile.conf URI=$tU@sbc1.mypeer.net From=<$fU@mynet.net> known To=<sip:$tU@mypeer.net> SER Call-ID=$ci_leg2 pseudo-variables ... SEMS SBC # # U 210.13.3.122:5080 -> 210.13.3.100:5060 U 210.13.3.100:5060 -> 213.192.59.75:5060 INVITE sip:+49123@osbc1.mynet.net SIP/2.0 INVITE sip:+49123@sbc1.mypeer.net SIP/2.0 From: “John” <sip:+431556221@mynet.net>;tag=12 From: <+431556221@mynet.net>;tag=3213 To: “Clara” <+49123@mynet.net> To: <sip:+49123@mypeer.net> Call-ID: 3cde5d1a960a-dez6oz34llo4 Call-ID: 3cde5d1a960a-dez6oz34llo4_leg2 ... ... 13
- 14. Replacement patterns ● RURI, From, To, PAI, PPI ($r, $f, $t, $a, $p) ● Call-ID ($ci) ● src, dst IP address/port ($si, $pi, $Ri, $Rp) ● P-App-Param hdr parameter ($P(myparam)) ● Header value ($H(P-My-Header)) ● Map any value via regexp ($M(val=>map)) 14
- 15. Control SBC from proxy dynamic_rtprelay_sst.sbcprofile.conf ... enable_rtprelay=$H(P-Enable-RTPRrelay) enable_session_timer=$H(P-Enable-SST) ... SEMS SBC # # U 210.13.3.122:5080 -> 210.13.3.100:5060 U 210.13.3.100:5060 -> 213.192.59.75:5060 INVITE sip:+49123@osbc1.mynet.net SIP/2.0 INVITE sip:+49123@sbc1.mypeer.net SIP/2.0 From: “John” <sip:+431556221@mynet.net>;tag=12 From: <+431556221@mynet.net>;tag=3213 To: “Clara” <+49123@mynet.net> To: <sip:+49123@mypeer.net> Call-ID: 3cde5d1a960a-dez6oz34llo4 Call-ID: 3cde5d1a960a-dez6oz34llo4_leg2 P-Enable-RTPRelay: no Session-Expires: 300 P-Enable-SST: yes ... ... 15
- 16. Profile selection ● Static ● active_profile=static_config ● Pseudo-var ipmap.conf ● active_profile=$rU ^10.0..*=>internal1 ^10.1..*=>internal2 ● Mapping urimap.conf iptel.org=>iptel ● active_profile=$M(val=>map) fliptel.com=>fliptel ● Select first matched ● active_profile=$M($si=>ipmap), $M($ru=>urimap),$H(P-SBCProfile),refuse 16
- 17. Manage SBC ● sems-sbc-* tools ● get and set active profile ● load and reload profiles ● load and reload mappings ● Track profile versions with MD5 hash ● Get statistics from monitoring 17
- 18. Processing model UDP other receiver/msg parser event sources threads Session Container RTP processing session pool event queues event processing ● Signaling: Async, one thread per call or thread pool ● Media: Sync, Thread pool 18
- 19. SEMS B2BUA architecture DIALOG DIALOG SIP message event SIP message ● Two complete, separate instances of dialog handling: Locally SIP correct 19
- 20. E.g.: Session Timers SST: refresh! Re-INVITE SDP changed? 200 Re-INVITE event: session changed 200 ● Use UPDATE or re-INVITE for refresh ● SST and timer values per leg ● Try to have e2e refresh 20
- 21. SBC programmability ● Pluggable Call Control modules for custom SBC application scenario ● e.g. policing with external data source Call control Call control Call control SBC SEMS core 21
- 22. Call control SBC-API ● V1: connect(...), start(...), end(...) ● Control SBC through call profile object ● Pattern replacements (provisioning) in both input and output ● Modules: CDR generation, call timer, prepaid, parallel calls limit, REST/http, REDIS blacklist 22
- 23. Programmability example (1) ● Call Forward settings via Web App ● Destination queried via REST interface 23
- 24. Minimal Play! Web app 24
- 25. ...with CRUD module 25
- 26. REST call control module ● Using libcurl for http request ● Result expected as JSON or TEXT (key=valuen) 26
- 27. Programmability example (2) ● In-memory Blacklist DB: REDIS ● Connection pool ● Configurable command ● SMEMBER blacklist $fU ● rate limiting with ZRANGE ● More complex logic in lua ● ... 27
- 28. Programmability example (3) FRAFOS: SBC with Provisioning and OAM GUI 28
- 29. FRAFOS: SBC high availability ● Replication of call state to hot standby ● Transparent fail-over 29
- 30. SBC performance 30