Outline NGN and SIGTRAN SCTP Motivation for SCTP Protocol - PDF document

Topics in Computer Networking Outline • NGN and SIGTRAN SCTP • Motivation for SCTP • Protocol Overview Stream Control Transmission – Packet format Protocol – Protection against SYN Flooding – Multistreaming – Multihoming Topics in Computer Networking • Research Activities at Kau • Summary • Seminar Details Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2009-0326 2010-04-07 Department of Computer Science Department of Computer Science NGN Network Convergence Network Application Server Manager • Traditionally, telecommunication and data IB AAA communication networks have been separate SNMP RADIUS API entities (PARLAY/LDAP) Softswitch SIP/SIP-T • Trend for voice, video, and data to converge into SG H.323/BICC single IP-based infrastructure (i.e. NGN) SIGTRAN SG SS7 SIGTRAN • VoIP step in this direction ISUP ISUP/MTP • Drivers of VoIP: Less costly equipment, less STP STP Switch Switch Softswitch SS7 SS7 SIP regulated, better efficiency, ease of deployment, PSTN/ISDN PSTN/ISDN MGC enhanced services MGCP/Megaco/H.248 Gatekeeper/ Proxy Server • Inhibitors of VoIP: immature technology, lack of Media standards, QoS (reliability/availability) Media Gateway Gateway H.323/SIP Mobile Networks/ • Need for seamless interoperation of VoIP with IMS Core IP Network traditional PSTN Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Н .323/ IP Network Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Anna Brunstrom 1

Topics in Computer Networking The Telephone Network SS7 Performance Requirements • A given route set should not be out of service for more Signaling System no. 7 (SS7) than 10 minutes per year (99.9998% uptime) • No more than 1x10 -7 messages should be lost Control Layer • No more than 1x10 -10 messages should be delivered out of Transport Layer sequence • Numerous timing requirements must be met • How to make sure that IP networks can support the performance requirements of SS7? Circuit Switched Network Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science How do we solve the problem? SIGTRAN Network Application Server Manager IB AAA SNMP RADIUS API (PARLAY/LDAP) Signaling Gateway Softswitch SIP/SIP-T SCP IP Network SCP SG H.323/BICC SIGTRAN SS7 SIGTRAN SG SS7 SIGTRAN ISUP ISUP/MTP Media PSTN Media Gateway STP STP STP Gateway Controller STP Switch MGCP/MEGACO Switch Softswitch SS7 SS7 Controller SIP PSTN/ISDN PSTN/ISDN MGC TDM RTP/IP MGCP/Megaco/H.248 RTP/IP Gatekeeper/ Media Proxy Server Media Gateway Local Exchange Gateway Media Media Gateway Gateway H.323/SIP Mobile Networks/ IMS Core IP Network Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Н .323/ IP Network Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Anna Brunstrom 2

Topics in Computer Networking SIGTRAN SCTP? IPSEP Signaling Gateway SS7SEP Applications (e.g Webbrowsers, mail clients, …) ULP NIF ULP TCP UDP SCTP M3UA M3UA MTP-L3 MTP-L3 SCTP SCTP MTP-L2 MTP-L2 IP IP IP MTP-L1 MTP-L1 Physical IP SS7 Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science SCTP: Motivation SCTP Standardization • TCP and UDP unsuitable for SS7 signaling • Stream Control Transmission Protocol (RFC 2960), – Can not be used, considering the previously mentioned SS7 October 2000 requirements • SCTP Partial Reliability Extension (RFC 3758), May • SCTP: 2004 – Like TCP, it provides reliable, full-duplex connections • SCTP Padding Chunk Extension (4820), March 2007 – Solves the following TCP issues: • SCTP AUTH Extension (RFC 4895), August 2007 • Head-of-line blocking can occur • SCTP DAR Extension (RFC 5061), September 2007 • Application layer framing is required for messages • Stream Control Transmission Protocol (RFC 4960), • Singlehomed hosts only September 2007 • Vulnerability to SYN flooding attacks • SCTP ≈ TCP + A number of features • Sockets API Extensions for SCTP, (internet-draft), latest version from March 2010 Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Anna Brunstrom 3

Topics in Computer Networking SCTP: Services and Features Why Messages? • TCP applications often transmit large byte Services/Features SCTP TCP UDP • • Full-duplex data transmission yes yes yes streams (bulk transfers) • Connection-oriented yes yes no • SCTP signaling applications transmit small • Reliable data transfer yes yes no • Partially reliable data transfer yes no no independent units of data • Ordered data delivery yes yes no • Flow and Congestion Control yes yes no • Selective acks yes yes no • PMTUD yes yes no • Application data fragmentation yes yes no • Preservation of message boundaries yes no yes • Protection agains SYN flooding attacks yes no n/a • Unordered data delivery yes no yes • Multistreaming yes no no • Multihoming yes no no Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Packet Formats SCTP Chunks • Type – Used to distinguish data chunks and different types of control Type N 2 1 1 chunks Flags • Flags Chunk Length – Usage depends on Chunk type ����� ���� • Length Value – Required because chunks have a variable length TCP • Value ����� ���� – Payload field SCTP Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Anna Brunstrom 4

Topics in Computer Networking Chunk Types 0 Payload Data 1 Initiation SCTP Data Chunk 2 Initiation Acknowledgement 3 Selective Acknowledgement 4 Heartbeat Request 5 Heartbeat Acknowledgement 6 Abort U B E Type = 0 Reserv. Length 7 Shutdown Type N 2 1 1 8 Shutdown Acknowledgement Transmission Sequence Number (TSN) Flags 9 Operation Error Stream Identifier S Stream Sequence Number N 10 State Cookie Length Chunk 11 Cookie Acknowledgement Payload Protocol Identifier 12 Reserved for Explicit Congestion Notification Echo Value 13 Reserved for Congestion Window Reduced 14 Shutdown Complete User Data (seq. n of Stream S) 15 Authentication chunk 128 Address Configuration Change Acknowledgement 132 SCTP packet padding 192 Forward Cumulative TSN 193 Address Configuration Change Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science SCTP: Services and Features SYN Flooding? Services/Features SCTP TCP UDP • • Full-duplex data transmission yes yes yes server client • Connection-oriented yes yes no • Reliable data transfer yes yes no • Partially reliable data transfer yes no no • Ordered data delivery yes yes no SYN • Flow and Congestion Control yes yes no • Selective acks yes yes no Resource Allocation • PMTUD yes yes no • Application data fragmentation yes yes no SYN, ACK • Preservation of message boundaries yes no yes • Protection against SYN flooding attack yes no n/a • Unordered data delivery yes no yes • Multistreaming yes no no ACK • Multihoming yes no no Anna Brunstrom Anna Brunstrom Topics in Computer Networking Topics in Computer Networking Karlstad University Karlstad University 2010-04-07 2010-04-07 Department of Computer Science Department of Computer Science Anna Brunstrom 5