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 Packet Header Parser Flow Table Algorithm TCP/IP Stack 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?