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Overhead and Performance Study of the General Internet Signaling Transport (GIST) Protocol Xiaoming Fu (Uni Goettingen) Henning Schulzrinne (Columbia Uni) Hannes Tschofenig (Siemens) Christian Dickmann, Dieter Hogrefe (Uni Goettingen) Telematics group University of Göttingen, Germany Telematics group University of Göttingen, Germany Overview • • • • Background Terminology Operation Overview Evaluation – – – – Overhead E2e performance Scalability Security • Conclusions Xiaoming Fu ([email protected]) 2 Telematics group University of Göttingen, Germany Background • Middlebox: interposed entity doing more than IP forwarding (NAT, firewall, cache, …) – Can also be QoS and other boxes – PHB, profile meters, AQM etc… Firewall B Host A NAT 10.1.1.4 QoS C New traffic class Host D • Not in harmony with the Internet architecture Xiaoming Fu ([email protected]) 3 Telematics group University of Göttingen, Germany Background • Perhaps need sort of common control plane functions for end-to-end communications – QoS is just an example of control functions – NAT, firewalls and other functions are also in consideration – One needs to perform certain configuration of such control functions before (and during) an end-to-end communication • Actually, this is somewhat re-inventing "circuit-switching" concept in ATM or telephony networks! • If we want to allow its use the Internet, a general signaling function for IP is necessary – Signaling: to install, maintain, remove states in network nodes – It needs to traverse heterogeneous IP-based nodes – It needs to cater for accommodating various controlling purposes Xiaoming Fu ([email protected]) 4 Telematics group University of Göttingen, Germany Network Control Signaling Protocol Examples • Path-decoupled (Client/Server) – – – – COPS MEGACO DIAMETER MIDCOM • Path-coupled – Resource Reservation Protocol (RSVP) IETF proposed standard for QoS signaling (03/97) – IETF NSIS (Next Steps in Signaling) with QoS signaling as first application Xiaoming Fu ([email protected]) 5 Telematics group University of Göttingen, Germany RSVP review • RFC 2205 • Integrated Service QoS models: GS, CLS – – – – – Per-flow reservation Multicast flow Limited extensibility (objects and semantics) Refreshes: packet losses due to congestion, route changes Not adapted to today’s needs • RFC 2961: added hop-by-hop reliability and summary refreshes • Other extensions: aggregated reservation, reservation over different networks (MPLS, 802.x) Xiaoming Fu ([email protected]) 6 Telematics group University of Göttingen, Germany Selected issues with RSVP • Insufficient modularity – Designed specifically for (IntServ) QoS – Difficult to accommodate new signaling applications: firewall/NATs, network diagnostics, etc. • No/difficult support for mobility – Node mobility has been an immense reality • Weak security framework and AAA support – No operator today will choose to deploy a solution without sufficient security for global Internet use Xiaoming Fu ([email protected]) 7 Telematics group University of Göttingen, Germany NSIS Framework (RFC 3726) • Flexible/extendable message transport – – – – Reliability/order provisioning Keepalive and multiplexing Some security services Common transport functions • Flexible/extendable multiple signalling application – – – – – Per flow QoS (IntServ) Flow aggregate QoS (DiffServ) Firewall and Network Address Translator (NAT) Traffic meter configuration And others • A two-layer split – Transport layer (NTLP or GIST): message transport – Signalling layer (NSLP): QoS NSLP, NATFW NSLP, etc. • Contains the application intelligence Xiaoming Fu ([email protected]) 8 Telematics group University of Göttingen, Germany NSIS Two-Layer Split Resource specific layer NSIS Signalling Layer (NSLP) NSIS Transport Layer (NTLP) Signalling Appl. Protocol Common Signalling ? ? IP forwarding Two names for transport layer: • NTLP (the basic concept) • GIST (the protocol implementation • General Internet Signalling Transport Xiaoming Fu ([email protected]) 9 Telematics group University of Göttingen, Germany GIST: NSIS Transport Layer (NTLP) • GIST responsible for – Transport signalling message through network – Finding necessary network elements • Abstraction of transport to NSLPs NSLP level – NSLP do not care about transport at all S ignalling A pplication -Q oS S ignalling S ignalling A pplication - A N O A pplication - m idcom G IS T S tate M aintenance NTLP level G IS T M essage E ncapsulation UDP DCCP S C TP IP S ecurity P rotocols (TLS , IP sec) TC P G IS T Focus of specification is this ...w hich includes m anagem ent of all of this IP Xiaoming Fu ([email protected]) 10 Telematics group University of Göttingen, Germany View on NSIS’ Layers Need QoS! NSLP View NSLP Stack Need QoS! NSLP Stack Here it is! Need QoS NSLP Stack Here it is! Here it is! Are you my next node? (discovery) Abstraction NTLP View Network View NTLP Stack UDP transport NTLP Stack NSIS router Router NSIS without Host A NSIS Xiaoming Fu ([email protected]) TCP connection Router without NSIS NSLP Stack NTLP Stack NTLP Stack NSIS router NSIS Host B 11 Telematics group University of Göttingen, Germany GIST Session Setup Xiaoming Fu ([email protected]) 12 Telematics group University of Göttingen, Germany Evaluation • Scalability – Can it be scalable for large number of sessions and nodes? • Extensibility and mobility – Can it be easily extended to build most signaling applications? – Can mobility be intrinsically supported? • Security – Can it be well protected without much performance penalty? • Overhead – Will the overhead added by NSIS be too large? Xiaoming Fu ([email protected]) 13 Telematics group University of Göttingen, Germany Extensibility and mobility • NSIS allows – GIST use of any types of discovery mechanism – Definition of any new NSLPs – node mobility: thru the use of independent NSIS session identifiers • Support a large variety of transport protocols – SCTP and PR-SCTP – TCP and its variants (both loss and delay based) – UDP (and even DCCP) • In the implementation level: – The GIST daemon and GIST-API are developed with sufficient modularity/independency on underlying platforms and NSLPs – Currently we support xBSD, Linux and MacOS: fairly easy to port Xiaoming Fu ([email protected]) 14 Telematics group University of Göttingen, Germany Performance testing: testbed Background Traffic generator Background Traffic generator S1 D1 100Mbps 100mbps S2 100mbps R1 100Mbps R2 1GMbps R2 100Mbps D2 100mbps 100Mbps D3 S3 H1 Xiaoming Fu ([email protected]) S3 15 Telematics group University of Göttingen, Germany Performance/scalability: 3 hops RSVP GIST (C-mode) Number of sessions 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 0 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 1000 RSVP 160 140 120 100 80 60 40 20 0 1000 Memory consumption (MB) GIST (D-mode) 80 70 60 50 40 30 20 10 0 0 Num ber of sessions 7 Avg. RTT (seconds) 6 5 4 3 2 1 Number of sessions 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 Xiaoming Fu ([email protected]) 5000 1000 0 0 CPU consumption (%) GIST (C-mode) 16 Telematics group University of Göttingen, Germany Overhead Xiaoming Fu ([email protected]) 17 Telematics group University of Göttingen, Germany Security • Two-layer security – Interconnected! • Transport layer (NTLP) – – – – Securing signaling transport Using TCP/SCTP with TLS Certificates Discovery phase: use of cookies • Signaling layer – Authentication and authorization – Policy decisions (e.g., user allowed to load filter rule?) Xiaoming Fu ([email protected]) 18 Telematics group University of Göttingen, Germany Conclusions • Extensible IP signaling framework (NSIS) tries to address the mobility, complexity, transport, and security issues in RSVP – Not only QoS signaling, but also generic signaling for any type of middlebox configuration – Fundamental building block: GIST protocol • GIST overhead is higher than RSVP but the complexity worth the added extensibility, modularity. • GIST performance is comparable with RSVP, with good scalability • GIST/NSIS implementation: http://user.cs.unigoettingen.de/~nsis Xiaoming Fu ([email protected]) 19 Telematics group University of Göttingen, Germany Thank you! Xiaoming Fu ([email protected]) 20