Technology for Adaptive Hard. Rui Santos, UA

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1 HaRTES Meeting Enhanced Ethernet Switching Technology for Adaptive Hard Real-Time Applications Rui Santos, UA

2 SUMMARY 2

3 MOTIVATION Switched Ethernet t became common in real-time communications Some interesting properties Large bandwidth Cheap network controllers Micro-segmentation ti Collisions are eliminated Multiple parallel forwarding paths High availability But there are still limitations FIFO queues Limited number of priorities Memory overflows Input ports Receiving buffers Packet handling - Address lookup - Traffic classification Switch Output Queues Scheduler Scheduler Output port ts 3

4 SOLUTIONS Commercial Of-The-Shelf Ethernet Switches Limiting the generated traffic by the application design Traffic shaping Master-Slave protocols (FTT-SE, ) Customized Ethernert Switches TTEthernet Profinet-IRT Static pre-defined configuration Online admission control is not generally available Miss on-line adaptation FTT-Enabled Switch (our solution) 4

FTT-SE FTT-ENABLED SWITCH (MECHANISM) Based on Flexible

technique Communication occurs in fixed slots (Elementary

asynchronous windows Supports synchronous, asynchronous

The ECs start with a Trigger Message (TM) sent by the

5 FTT-SE FTT-ENABLED SWITCH (MECHANISM) Based on Flexible Time-Triggered Paradigm Master-slave transmission control technique Communication occurs in fixed slots (Elementary Cycles Ecs) ECs are organized in synchronous and asynchronous windows Supports synchronous, asynchronous and non real-time traffic, with strict temporal isolation The ECs start with a Trigger Message (TM) sent by the Master (switch), that contains the schedule for each EC TM EC time 5

6 FTT-ENABLED SWITCH (PROPERTIES) Traffic scheduling and management Global traffic coordination in a common timeline Supports online admission control and dynamic QoS management Allows arbitrary traffic scheduling policies Traffic classification, confinement and policing Seamless integration of standard non-ftt-compliant nodes without jeopardizing the real-time services Asynchronous traffic is autonomously triggered by the nodes Unauthorized transmissions i can be readily blocked at tthe switch input ports, thus not interfering with the rest of the system 6

7 HOW CAN WE IMPLEMET THAT? FTT-ENABLED SWITCH (ARCHITECTURE) Complex Algorithms Admission control Difficult HW Implementation QoS Manager SRDB Code Scheduler Reuse EC Schedule FTT-SE Dispatcher Master Packet forwarding Master messages NRT packet (Queue) Validate Classifier Invalid Predictability Async. (Queue) FTT packet Memory pool NRT Sync. (Queue) Validation data Determinism Async Packet Po ort 1 Up Input ports Port 1 Packet list Syn Asyn NRT Port dispatcher Port N Packet list Syn Asyn NRT Sync Sync. (Queue) Speed of execution Port dispatcher Async. (Queue) Invalid Va alidate FTT packet Pa acket Classifier Port N Up Output ports 7

8 FTT-ENABLED SWITCH (IMPLEMENTATION) Switching Module Implemented in hardware Master Module Implemented in FPGA embedded processor (Syntesizable or Hardwire) Utilization of a CPU communication with the FPGA is carried out by the conventional interface (Ethernet, USB, PCI, ) 8

9 FTT-ENABLED SWITCH (IMPLEMENTATION) 9

10 FTT-ENABLED SWITCH (EXPERIMENTAL RESULTS) TRAFFIC CONFINEMENT Submitted traffic 1kB packets, T avg = 250μs ingress TM Offset at the switch egress (relative to the TM) egress time EC (1ms) RT Window NRT Window 10

11 FTT-ENABLED SWITCH (EXPERIMENTAL RESULTS) REGULARITY OF THE TM TM TM time Measures: T_TM avg = 1,000ms T_TM max = 1,0003ms T_ TM min = 0,99998ms STD_TM = 138ns Jitter purely from the switch 11

12 SERVER-BASED TRAFFIC SCHEDULING Motivation Address the growing NES requirements to: support streams with arbitrary arrival patterns provide QoS guarantees. Solution o We propose to integrate CPU based server policy in the FTT-Enabled Switch Polling Server, Deferrable Server, Sporadic Server ingress egress Providing hierarchical composition, reconfigurability and adaptability Online creation, deletion and adaptation of servers x xx Server 12

13 SERVER-BASED TRAFFIC SCHEDULING (INTEGRATION) First Level SW Polling Server AW Polling Server or a Deferrable Server Second Level Manages the sporadic and the NRT traffic inside the AW Third Level Implements specific servers, virtual channels 13

Hardware (Switching Module) High reactivity

is fixed) Complex server scheduling methods

14 SERVER-BASED TRAFFIC SCHEDULING (IMPLEMENTATION) Servers implemented in Hardware (Switching Module) High reactivity Less flexibility (the number of the servers is fixed) Complex server scheduling methods can require a significant amount of hardware resources. Servers implemented in Software (Master Module) High flexibility The server latency is relatively large 14

15 SERVER-BASED TRAFFIC SCHEDULING (EXPERIMENTAL RESULTS) Elemantary Cycle = 1ms; Asynchronous Window = 42% SS1, SS2 sporadic servers with C=3200B and T=1ms BS backgound server uses the remaining i bandwidth Video SS1 Peak load = 21.9 Mbps UDP SS2 Average load = 99.9Mbps9Mb 15

16 SERVER-BASED TRAFFIC SCHEDULING (EXPERIMENTAL RESULTS) Video SS1 Traffic gen. SS2 TCP BS 16

17 THE SAME EXPERIMENT WITH A NORMAL SWITCH! Video SS1 Traffic gen. SS2 TCP BS 17

FTT-ENABLED SWITCH (MULTIPLE SWITCHES) Problem

Solutions Network with one FTT-Enabled Switch

18 FTT-ENABLED SWITCH (MULTIPLE SWITCHES) Problem How to create a network with multiple switches, where the communication is based on the FTT-Enabled Switch (HaRTES)? Solutions Network with one FTT-Enabled Switch and multiple COTS switches Network with multiple FTT-Enabled Switches 18

19 FTT-ENABLED SWITCH (MULTIPLE SWITCHES) Network with one FTT-Enabled Switch and multiple COTS switches Properties Trigger Messages are generated by FTT-Enabled Switch and disseminated by the others switches Advantages and Disadvantages Solution compatible with common networks COTS switches don t perform traffic policing The Trigger Message latency can generate problems of synchronization TM 19

20 FTT-ENABLED SWITCH (MULTIPLE SWITCHES) Network with multiple l FTT-Enabled Switches Properties Each FTT-Enabled Switch creates its own synchronization domain It needs a gateway to interconnect different synchronization domains Gateway can be avoided if FTT-Enabled Switches are slaves to each other Advantages and Disadvantages Whole network is covered by the traffic policing It needs a gateway TM TM Gateway 20

21 FTT-ENABLED SWITCH (CURRENT STATUS) HaRTES/B Basic switching Capability to separate different traffic classes On-line scheduling HaRTES/S Error detection Traffic policing HaRTES/Q Dynamic QoS management capabilities 21

22 CONCLUSIONS The growing availability of FPGAs, associated tools and communication IP cores opens the way to build customizable devices with properties that are tuned to specific application domains We propose an enhanced Ethernet switch that: Provides seamless integration of any (kind of) nodes without causing any interference Provides filtering i of unauthorized transmissions i Allows arbitrary synchronous traffic scheduling policies Allows arbitrary server scheduling and hierarchical composition Provides dynamic creation and adaptation of servers 22

23 ON GOING AND FUTURE WORK Finish the proposed work in the project Study and integrate multiple switch architecture Adapt the enhanced switch to allow integration in architectures with multiple synchronization domains Replicate the Master Study over the schedulability analysis of the server-based traffic scheduling 23

24 THANK YOU 24

Enhanced Ethernet Switching Technology. Time Applications. Rui Santos 17 / 04 / 2009

Enhanced Ethernet Switching Technology for Adaptive Hard Real- Time Applications Rui Santos (rsantos@ua.pt) 17 / 04 / 2009 Problem 2 Switched Ethernet became common in real-time communications Some interesting