1 / 14

TCP vs. SCTP in high-speed cluster environment

TCP vs. SCTP in high-speed cluster environment. Miklos Kozlovszky Budapest University of Technology and Economics BUTE. Outline. Introduction to SCTP Basic comparison Features Performance. SCTP introduction Stream Control Transmission Protocol. Message oriented Multiple streams

rhoda
Télécharger la présentation

TCP vs. SCTP in high-speed cluster environment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TCP vs. SCTP in high-speed cluster environment Miklos Kozlovszky Budapest University of Technology and Economics BUTE

  2. Outline • Introduction to SCTP • Basic comparison • Features • Performance

  3. SCTP introductionStream Control Transmission Protocol • Message oriented • Multiple streams • Solution to HOL issue One stream may be blocked – the other streams work on • End-host multi-homing • Continuous path monitoring • Reliable transmission • Reliable data delivery - Transmission Sequence Number • Selective acknowledgements • Packet validation (Verification Tag) • Heartbeat keep-alive mechanism

  4. SCTP Packet format • Common header for the whole packet • 1..N control or data chunks • 17 types of control chunks /very extensible/ • 1 type of data chunk SCTP Common Header Control Chunk Data Chunk

  5. TCP vs. SCTP Both: • IPv4 & IPv6 compatible • Reliable • Connection oriented • Offers acknowledged, error free, non-duplicated transfer • Almost same Flow and Congestion Control

  6. TCP weaknesses • Lack of integrity/robustness checks16-bit CRC used by TCP is inadequate at multi-gigabit rates • Lack of high availability option • Susceptibility to denial-of-service (DoS) attacks • Poor support for QoS • Effective implementation of RDMA becomes very difficult on top of a byte stream abstraction (memory BW, caching and access latency issues)

  7. SCTP features • Flexible ordering Each stream can be designated for an in-order or immediate delivery to the upper layer (unordered delivery reduces latency). • Multi-streaming(The flow and congestion control are still on a per association basis) • Multi-homing /multiple “endpoints”/ increases connection level fault tolerance • Protection against denial of service • Robust association (connection) establishment verification tag+ 32-bit CRC and heartbeat mechanism • Can interface with RDMA easily (message oriented) • Very flexible and extensible protocol

  8. WAN vs. cluster needs • Cluster communication • High level of service availability • Low end-to-end latency • Less variable round-trip times • Data rates: 100Mbps-10Gbps • Efficient multi-party communication • Requirements • Special QoS needs (application specific bandwidth) • Low processing overhead • Low communication latency • Low CPU utilization • Good Configurable • Wide OS support • WAN communication • High level of link availability • Large end-to-end latency range • Variable round-trip times • Data rates:1.5Mbps-400Gbps • Requirements • Automatically adapt to the changing environment • Highest possible throughput on lossy links • Be fair to other competing flows

  9. Measurements and Simulations • Simulation • NS-2 network simulator • Measurements • Point-to-point measurements • Machines • Hardware • Pentium 4, with RedHat Fedora Core3, • Intel and Realtek GE NICs • Software • Gnet- own cluster (NxM node) performance measurement software • iPerf and Ethereal, tcpdump

  10. Performance comparison I. • Theoretical study in network simulator (NS-2) • Perform better than TCP • Fair to TCP and to UDP data flows • Real case scenarios – hard to compare • Perform differently on different OSs • Implementation problems • Less effective than TCP (except BSD) • Almost same CPU utilisation as TCP (bad) • HW offloading • TCP checksum offload and transport segmentation offload (TSO) is not supported on available NICs for SCTP.

  11. Performance comparison II. • SCTP is using CRC-32, TCP: CRC-16 this increase the protocol processing cost by 25%-45% • TCP is faster and even if we disable NAGLE algorithm, and CRC calculation TCP is less CPU intensive (due bad implementation…) • On lossy networks SCTP work a bit better

  12. SCTP availability • It’s relative new… • Linux • Kernel space • Lksctp http://lksctp.sourceforge.net/ (from kernel 2.4 optional) • OpenSS7 SCTP http://www.openss7.org • FreeBSD + Apple MAC • KAME (Reference implementation) http://www.kame.net • SUN - Solaris9,10

  13. GRID aspects • SCTP is suitable for GRID because • More secure than TCP • High Availability support for services • Works good on long haul, big delay links

  14. Summary • SCTP inherited all the “good features of TCP” • SCTP want to behave like a next generation TCP • It is more secure than TCP, and has many attractive feature (e.g.:multihoming) • Theoretically it can work better than TCP, but TCP is faster (yet “poor” implementations) • Well standardized, and can be useful for cluster

More Related