Flexible Time-Triggered Switched Ethernet Lus Almeida 1 , Zahid Iqbal - - PowerPoint PPT Presentation

Developments in FTT-SE Flexible Time-Triggered Switched Ethernet

Luís Almeida1, Zahid Iqbal1, Paulo Pedreiras2, Ricardo Marau2, Luis Silva2, Mohammad Ashjaei3, Moris Behnam3, Thomas Nolte3, Julian Proenza4, Manuel Barranco4, David Gessner4, Guillermo Rodriguez-Navas4, Alberto Ballesteros4, Sinisa Derasevic4

1 IT / DEEC – Faculty of Engineering, University of Porto, Portugal 2 IT / DETI – University of Aveiro, Portugal 3 MRTC – Mälardalen University, Sweden 4 DMI –University of the Balearic Islands, Spain

RATE 2013 (RTSS 2013), Vancouver, Canada

universidade de aveiro

RT-enabled cloud

Motivation

• Open / reconfigurable / adaptive

network-centric real-time applications

– Multimedia streaming and interactive multimedia, – Flexible cells and industrial multimedia – Reconfigurable vehicles – Data centers and real-time cloud – Flexible/open Cyber-Physical Systems – …

• Real-time reconfiguration / adaptation

– Maintain real-time guarantees – While

• adding / removing data streams
• Managing bandwidth

An adequate network abstraction

• Dynamic virtual channels

– simple composable channel interface

• Capacity(B), deadline, period, jitter

– can be created / destroyed / adapted

• Hierarchical channel composition

– channels of channels

• Ranges in interface declaration

– acceptable vs desireable performance levels

The FTT paradigm

• Concentration of operational information

– Master node with

• System Requirements Data Base
• Online System Scheduler

– Consistent and prompt channels management

• Emanating triggers to the system
• Isochronous / asynchronous traffic
• Any scheduling policy

master SRDB SS Transmits periodic trigger messages with adequate schedule

http://www.fe.up.pt/ftt

FTT-SE internals

 Master schedules traffic per cycles  Only traffic that fits in the cycle is scheduled  Eliminates memory overflows  Supports any scheduling policy

 Full priorities  Deadline-based  Server-based  …

FTT master

TM

Trigger message Ethernet switch

Sig

FTT-SE traffic scheduling

 Integrated scheduler for all traffic types

TM Sync req SM1 (...) SM2(...) ... sched FP, EDF, ...

M nodes

e

Switch with M ports FTT master

lu

j

ld

j

SMi

Broadcast to all nodes

Nodes reaction to the TM in a given EC

sched

Async requests

Sync: SRT = {SMi: SMi(Ci, Di, Ti, Oi , Pri, Si, {R1i .. Rkii}), i=1..NS} Async: ART = {AMi: AMi(Ci, Di, miti, Pri, Si, {R1i .. Rkii}), i=1..NA}

Sig1 SigM

...

M nodes

The HaRTES switch

An FTT-enabled switch

• Main features:

– Same properties as FTT-SE plus:  Seamless integration of non-FTT nodes  Seamless support for real-time channels  Traffic polycing  Asynchronous traffic managed with hierarchical servers implemented in HW

HaRTES switch FTT Master

TM

http://www.ieeta.pt/lse/hartes http://serv-cps.av.it.pt/

HaRTES switch internal architecture

Scheduler SRDB QoS Manager Admission control Dispatcher EC Schedule

Port 1

Packet Classifier Validate

Up Port 1

Packet forwarding Port dispatcher

Packet list Syn Asyn NRT Port N

Port dispatcher

Packet list Syn Asyn NRT FTT packet NRT packet (Queue) Async. (Queue) Sync. (Queue)

Memory pool

NRT Sync Async

Packet Classifier Validate

Up Port N FTT packet Sync. (Queue) Invalid Async. (Queue) Master messages Output ports Input ports Invalid Validation data

FTT-master Input side Memory Output side

Scaling up the network

• Multiple switches per master domain (FTT-SE)

– Not so efficient because of limited load per cycle

Scaling up the network

• Single switch per master domain (FTT-SE / HaRTES)

– Interconnection with bridges Manage channels locally Provide channels globally Resource reservation protocol (global channels)

Flexibility and Dependability

• The centralized nature of traffic control in the FTT paradigm

creates two single points of failure

– FTT master – Communication hub/channel

• In critical applications this must be solved

– Classical approach: replicate both master and hub/channel

Flexibility and Dependability

• The on-going FT4FTT-Ethernet project goes beyond and targets

all dependability-related vulnerabilities

– FTTRS to replicate both FTT master and switch – ReTOPS to ensure consistent multicast transmissions taking advantage of the global view of HaRTES switch – A node replication scheme is being devised based on an enhanced HaRTES switch that restricts node failure semantics

• These mechanisms are being designed to work together for

significantly increasing the complete system reliability

Examples

Virtual channels Heterogeneity Traffic isolation

Examples

Services implementations composed online

C1 H C2 L DH DL C2 H C2 L

Reconfiguration

Examples

Openness Adaptation

Dynamically reconfigurable virtual channel with definable temporal properties

Examples

Dynamically reconfigurable VLAN with definable temporal properties

Examples

Openness Integration

Dual network stack

Wrapping up

• FTT-SE / HaRTES use dynamic resource reservation to

partition switched Ethernet networks in a hierarchical and composable way

• Provide a channel abstraction that facilitates integration

with application models for Cyber-Physical Systems

• It is currently probably the only solution for
• pen and adaptive systems with a combination of

isochronous/asynchronous traffic How relevant is this ?!