... | ... | @@ -192,7 +192,8 @@ New ideas: |
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- Siemens
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([page 14](http://www.ieee802.org/1/files/public/docs2011/new-avb-nakamura-automotive-backbone-requirements-0907-v02.pdf))
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- max latency / hop \< 3us
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- topology (quite) independent (Daisy Chain / Comb / Ring)
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- topology (quite) independent latency (required topology
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support: Daisy Chain / Comb / Ring)
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- main network characteristics: max 512 devices, max hps: 64
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- traffic characteristics: "control data" size (payload):
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typical 10-300 bytes, more possible, max of 4096 streams
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... | ... | @@ -227,7 +228,8 @@ The enhancements to current IEEE 802.1AS include |
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### P802.1Qbv : Enhancements for Scheduled Traffic - Time Aware Shaper
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- to provide lower network delays for time-sensitive data
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- goal of improvements: provide lower network delays for
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time-sensitive data
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- defines ways for bridges and end stations to schedule the
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transmission of frames based on timing derived from IEEE Std 802.1AS
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- Time Aware (Blocking/De-blocking) Shaper in bridges and end
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... | ... | @@ -237,19 +239,19 @@ The enhancements to current IEEE 802.1AS include |
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sent - enables to ensure that time-sensitive traffic does not
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interfere with best-effort traffic (the former does not need to wait
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for the latter to be finished sending)
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- it seems that its usage is more efficient with preemption
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- it seems that it is most efficient with preemption
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([page 15](http://www.ieee802.org/1/files/public/docs2011/new-avb-boiger-meeting-gen2-latency-req-1111.pdf))
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- preemption enables to decrease the bandwidth overhead
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- preemption enables to decrease the bandwidth overhead of
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introducing time-window for critical data
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([page 11](http://www.ieee802.org/1/files/public/docs2012/new-avb-nfinn-preempt-advantage-0112-v02.pdf))
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### P802.1Qbu : Frame Preemption
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- to provide lower network delays
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- goal: provide lower network delays
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- allows very time-sensitive packets to interrupt a normal best-effort
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packet being transmitted on an egress port and then resume it once
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the time-sensitive packet has been
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transmitted
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- [pages 30](http://www.ieee802.org/1/files/public/docs2011/new-pannell-latency-options-0311-v1.pdf)
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the time-sensitive packet has been transmitted
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([pages 30](http://www.ieee802.org/1/files/public/docs2011/new-pannell-latency-options-0311-v1.pdf))
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- most efficient when used with Time Aware Shaper (would be defined in
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P802.Qbv),
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[page 15](http://www.ieee802.org/1/files/public/docs2011/new-avb-boiger-meeting-gen2-latency-req-1111.pdf)
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... | ... | @@ -265,13 +267,14 @@ The enhancements to current IEEE 802.1AS include |
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- static redundancy - redundant paths from the source to the
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receiver exist and are used at any time - duplication of frames
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must be handled by the receiver (provides seamless redundancy)
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- dynamic redundancy - redundant paths from the source to the
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receiver exist but only one is used at a time - no duplication
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at the receiver
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- proposed solutions
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- General Motors: redundancy of physical or logical (VLAN)
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network or ring topology (like
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[HSR](http://en.wikipedia.org/wikis/High-availability_Seamless_Redundancy)),
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[see](http://www.ieee802.org/1/files/public/docs2012/new-avb-jochim-redundancy-requirements-GM-perspective-AVB2-0312.pdf)
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- dynamic redundancy - redundant paths from the source to the
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receiver exist but only one is used at a time - no duplication
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at the receiver
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- Toyota: quick version of RSTP+802.1AS+802.1Qat (\< 100ms),
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[page 6](http://www.ieee802.org/1/files/public/docs2011/new-avb-KimNakamura-automotive-network-requirements-0311.pdf)
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- Broadcom: abandon RSTP, improved MSRP (802.1AS defines SRP,
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