Multicast Parallel Pipeline Router Architecture for NetworkonChip

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Multicast Parallel Pipeline Router
Architecturefor Network-on-Chip

• Author Faizal A. Samman, Thomas Hollstein,
  Manfred Glesner,
• Speaker ???
• DATE,2008

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About this paper

• Present a flexible mesh router architecture
  supporting unicast and multicast service
• A flexible mechanism to manage broadcast flow

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Introduction

• By the end of this decade, the transistor feature
  size will be 50-nm and it operates below one
  volt. requirements and should be scalable for
  wide range. (ITRS)
• SoCs will grow to 4-billion transistors running
  at 10 GHz.
• A limiting factor for the performance, and energy
  consumption will be on-chip physical
  interconnections

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Introduction

• Networks-on-Chip provide advanced intellectual
  properties IP communication concepts for SoCs
• Sharing the wires between several communication
• flows makes the use of the wires more efficient

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Traditional 4X4 mesh NOC topology
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NoC design principle

• The architecture and routing decision must meet
  bandwidth requirements and should be scalable for
  wide range
• of applications
• For example
• Network topology could influence the scalability
  and performance

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Synchronous /Asynchronous design

• Synchronous
• Extra clock power consumption
• electromagnetic interference effect
• Asynchronous
• A promising concept
• lacks of industrial standard support, especially
  with respect to testability issues

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General router architecture for XHiNoC

• Port
• FIFO
• Routing engine
• ID manager
• Link state controller

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Packet format

• Using 3 bits to record packet type (header ,body
  ,tail)
• Using 3 bits to record local id number to
  differentiate it from another

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Multicast procedure

• Forwarding Header Flits
• A header flit by a header flit
• Record the direction based on its ID in
  registers
• Broadcasting Payload Flits
• Each time a flit appears in the FIFO output, the
  LUT (look up table ) will check its ID to find
  its directions in the routing table

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ID-tag-basedMulticast Routing

• Two issues
• Packet flows are controlled based on ID-tags
• All flits of a packet have the same ID-tag on a
  certain communication link

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ID-tag-basedMulticast Routing
Routing engine
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Packet Identity Management

• IDM
• IDM Update new ID for new packet flowing through
  the outport.
• Guarantee that different packets will have a
  different ID-tag.
• Stop forwarding when IDs is run out.
• Delete all information about a certain ID when
  the tail flit flows through IDM

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Synchronous Parallel Pipelined Switching
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Synchronous Parallel Pipelined Switching

• 1st cycle RE sends direction request signals to
  the LCFS
• 2nd cycle The arbiter in the LCFS has selected
  the winner to access the outport by sending a
  grant

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Multicast Broadcast-flow Management

• LCFS(Link Controller and Flow supervisor)
• Three major part
• DecMC unit decodes 3-bit routing direction
  request signals from all inports into 1-bit
  signals.
• arbiter is in charge of selecting a winner of all
  the requests
• GMC is in charge of granting the FIFO

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Multicast Broadcast-flow Management
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Multicast Broadcast-flow Management

• Why forwarding
• For instance
• When one of the direction is not win the
  arbitraction
• Using forwarding could reset the successful way
  to avoid the flit being forwarded more than once
  into the same outport

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Broadcast-FlowManagement
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Experiment Results

• Experiment setting
• injecting 2 multicast packets,which have 7
  destinations in 2-D 4x4 mesh topology.
• Each packet consists of 128 flits,it means, that
  each packet header is followed by 121 payload
  flits
• Traffic scenarios

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Experiment Results
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Experiment Results

• By using UMC 180nm standard-cell technology
• The XHiNoC can be run at 230 MHz. Total number of
  logic cells is 10577. Migrating from unicast to
  multicast with
• The same XY routing algorithm increases 15 of
  total logic cells using unicast service (9201
  logic cells). Five FIFO buffers occupy 44 of
  total cell area

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Conclusion and future work

• Propose a new mechanism to serve multicast packet
• For future works
• Adaptive routing algorithms