Telematics group University of Göttingen, Germany 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)

2 Telematics group University of Göttingen, Germany Xiaoming Fu Overview Background Terminology Operation Overview Evaluation –Overhead –E2e performance –Scalability –Security Conclusions

3 Telematics group University of Göttingen, Germany Xiaoming Fu Background Middlebox : interposed entity doing more than IP forwarding (NAT, firewall, cache, …) –Can also be QoS and other boxes – PHB, profile meters, AQM etc… Not in harmony with the Internet architecture NAT B Host A New traffic class Firewall Host D C QoS

4 Telematics group University of Göttingen, Germany Xiaoming Fu 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

5 Telematics group University of Göttingen, Germany Xiaoming Fu 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

6 Telematics group University of Göttingen, Germany Xiaoming Fu 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)

7 Telematics group University of Göttingen, Germany Xiaoming Fu 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

8 Telematics group University of Göttingen, Germany Xiaoming Fu 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

9 Telematics group University of Göttingen, Germany Xiaoming Fu NSIS Two-Layer Split NSIS Transport Layer (NTLP) NSIS Signalling Layer (NSLP) Two names for transport layer: NTLP (the basic concept) GIST (the protocol implementation General Internet Signalling Transport

10 Telematics group University of Göttingen, Germany Xiaoming Fu GIST: NSIS Transport Layer (NTLP) GIST responsible for –Transport signalling message through network –Finding necessary network elements Abstraction of transport to NSLPs –NSLP do not care about transport at all

11 Telematics group University of Göttingen, Germany Xiaoming Fu TCP connection View on NSIS’ Layers NSIS Host A NSIS Host B NSIS router Network View Router without NSIS Router without NSIS NSIS router NTLP View NTLP Stack NTLP Stack NTLP Stack NTLP Stack NSLP View NSLP Stack NSLP Stack NSLP Stack NSLP Stack UDP transport Are you my next node? (discovery) Need QoS! Here it is! Abstraction Need QoS! Need QoS

12 Telematics group University of Göttingen, Germany Xiaoming Fu GIST Session Setup

13 Telematics group University of Göttingen, Germany Xiaoming Fu 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?

14 Telematics group University of Göttingen, Germany Xiaoming Fu 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

15 Telematics group University of Göttingen, Germany Xiaoming Fu Performance testing: testbed

16 Telematics group University of Göttingen, Germany Xiaoming Fu Performance/scalability: 3 hops

17 Telematics group University of Göttingen, Germany Xiaoming Fu Overhead

18 Telematics group University of Göttingen, Germany Xiaoming Fu 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?)

19 Telematics group University of Göttingen, Germany Xiaoming Fu 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: goettingen.de/~nsis

20 Telematics group University of Göttingen, Germany Xiaoming Fu Thank you!