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8/7/2019 Enhanced Flow Control in Ethernet Network
http://slidepdf.com/reader/full/enhanced-flow-control-in-ethernet-network 1/15
Xsigo Systems 1
Enhanced Flow control inEthernet Networks
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 2
Agenda
• Review the proposal to support thecommunication of congestion information
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 3
Some Facts …
• Ethernet has fulfilled the expectations of applications with best effort delivery model forpast 3 decades
• Throwing more bandwidth at the problem does not
solve congestion problem since queuing delays aremore than wire delays• Convergence of mission critical and non-mission
critical applications over shared network infrastructure require traffic differentiation
• Is it time to enhance ethernet?
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 4
Ethernet : Is it time to enhance it?
– Businesses rely heavily on predictable performance of IT andnetwork infrastructure
– Businesses needs more intelligent and adaptable network infrastructure to meet business needs
– Commoditization of compute and sharing of same network infrastructure between mission critical and non-mission criticalapplications require
• Intelligent network infrastructure with prioritization anddifferentiation of traffic
• Guaranteed performance per traffic type to meet business SLA
• Ethernet requires enhancements not disruptive changes
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 5
802.1p and Flow control in Ethernet Networks
Server #1
Switch #1
Server #2
Switch #2
Ethernet Pipe
Ethernet Pipe
Flow Control
Flow
ControlCongestion
Point
Ethernet Pipe
FlowControl
E t h er n
e t
P i p e
F l
ow
C on
t r ol
Server #3
Flow control inEthernet Networks
802.1p supports
prioritizationof the traffic
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Xsigo Systems 6
Flow control
• Limitations– One traffic class affect another in true loss-less fabric
implementation• Flow control (802.3X) does not have prioritization• One VLAN traffic can block another VLAN traffic
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 7
Flow control Requirements
• Traffic type differentiation– Congestion should be reported based on traffic types,
E.g. priority, {VLAN,Pri}, other finer level flows arepossible, not relevant in this group
– Avoid head-of-line blocking between traffic types
• Fairness– Congestion information should be reported to all the
sources who can potentially send traffic to congesteddestination
• Keep Flow control traffic as low as possible
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 8
Flow control Proposal
• Flow control per VLAN per priority• Flow control packet per VLAN can be
broadcasted back to all the sources to turnoff traffic destined to a MAC address (End node) orgroup of MAC addresses going throughcongested switch port
• This is in addition to link level flow control
defined today
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Xsigo Systems 9
Flow control Example
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Xsigo Systems 10
Congestion Point #1
• Switch #1’s output port connected to switch #2 is congested• This port carry traffic for server #6, VLAN A and server #7,
VLANB• Ingress side of this port sends two broadcast flow control packets• One on VLAN A
– Packet includes DMAC 6, VLAN A, Priority and time to stop
etc …• One on VLAN B
– Packet includes DMAC 7, VLAN B, Priority and time to stopetc …
• Traffic towards server #5 will not be affected
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 11
Congestion Point #2
• Server #7 is congested• Server #7 sends broadcast flow control packet on
VLAN B to all sources belong to same VLAN– Packet includes DMAC 7, VLAN B, Priority and time
to stop
• Traffic towards any other server except #7 will notbe affected!
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 12
Congestion Point #3
• Server #6 is congested• Server #6 sends broadcast flow control packet on
VLAN B to all sources belong to same VLAN– Packet includes DMAC 6, VLAN B, Priority and time
to stop
• Traffic towards any other server except #6 will notbe affected!
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 13
Congestion Point #4
• Server #5 is congested• Server #5 sends broadcast flow control packet on
VLAN A to all sources belong to same VLAN– Packet includes DMAC 5, VLAN A, Priority and time
to stop
• Traffic towards any other server except #5 will notbe affected!
8/7/2019 Enhanced Flow Control in Ethernet Network
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Xsigo Systems 14
Summary
• Ethernet needs enhancement in congestionreporting mechanism back to sources– The mechanism has to be fair to all the sources
• Use VLAN based broadcast support to reportcongestion information back to sources withfairness
• This proposal allows to differentiate various traffic
types on ethernet networks with fairness andguaranteed service
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Xsigo Systems 15
Thank You