Transcript ICTCP: Incast Congestion Control for TCP in Data Center Networks By: Hilfi Alkaff.

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?