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ICTCP: Incast Congestion Control for TCP in Data Center Networks By: Hilfi Alkaff. Problem: Incast Congestion. - Occurs as the number of storage servers sending data to a client increases past the ability of an Ethernet switch to buffer packets. Solution: Modify RCWND Dynamically.
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ICTCP: Incast Congestion Control for TCP in Data Center Networks By: Hilfi Alkaff
Problem: Incast Congestion - Occurs as the number of storage servers sending data to a client increases past the ability of an Ethernet switch to buffer packets.
Solution: Modify RCWND Dynamically • Should not be too small or too big. • Done on the receiver side. • No modification to TCP option + header. • Implemented as Windows NDIS.
Algorithm • Calculate available bandwidth → Increase when enough quota • Divide window to two slots. In 1st sub-slot, rcwnd cannot be increased but in 2nd sub-slot, it could be increased up to the available bandwidth observed in 1st slot
Algorithm (Contd) Measured throughput: Current application requirement over the TCP connection → max (observed throughput, exponentially filtered throughput) Expected throughput: Throughput that is achieved if only constrained by rcwnd → max (measured throughput, rwnd/RTT)
Implementation: Windows NDIS TCP/IP Stack Flow Table Packet Header Parser Algorithm NIC Driver
Other solutions? • Larger switch buffers • Effective Fine-grained TCP Retransmissions for Datacenter Communications (SIGCOMM 2009) • Efficient Packet Transport for the Commoditized Data Center (SIGCOMM 2010) • TCP Vegas
Discussion/Comments • (Un)fairness • Moving to non-driver solution? • Hella grammatical errors • Different topology?