Arbitration Team

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Arbitration Team

• Pablo Molinero, Isaac Keslassy, Rui Zhang,
  Gireesh Shrimali,
• Weihong Pang, Wensheng Hua

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Problems

• 1) Arbitration Computation
• Number of ports
• 625
• (today 32)
• Speed
• Cell time 64 B /160 Gbps 3.2 ns about one
  clock cycle
• (todays cell time 50 ns)

Solution use several smaller routers
Solution simplify computations and/or make
decisions less frequently
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Problems

• 2) Communication
• Number of serial links
• 625 bidirectional
• (today 170 links)
• Speed of serial links
• Information flow rate 0.3 G-cells/s x 20
  bits/cell 6 Gbps
• (todays capacity 2.5 Gbps)

Solution several chips
Possible solution multiplexing (?)
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Requirements From Other Groups

• Need to know
• Reconfiguration delay of crossbar
• Instantaneous bandwidth (speed up)
• Any other constraints

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Candidate Architectures

• Pipelining
• Need to be very deep
• Either dependent stages or wasted bandwidth
• Keep a decision for k time slots
• Wastes some bandwidth
• Can improve by taking weights into account (use a
  few bits to represent queue lengths)

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Candidate Architectures

• Use bigger cells
• Similar to keeping a decision for k time slots
• Use circuit switch for core
• Estimate the rate matrix
• Need either complicated decomposition or fast
  buffering at output