Transport congestion control and AQM

TCP

• Tahoe
• Reno
• NewReno
• Vegas
• SACK
• ECN
• BIC
• CUBIC
• DC-TCP
• BBR (overview)

The default window size in TCP is 64 KB (2^16).  Newer versions of TCP have a window scale option that allows the window to be scaled by 2^14, so the total window size is 2^30 or 1 GB.  However, some implementations only allow a limited window size.

RoCEv2

• Mellanox recommended configuration
• DCQCN (data center quantized congestion notification)
• Note that end station algorithm for reacting to congestion is not standardized
• PCN (photonic congestion notification)

QUIC

AQM 

• RED, WRED, RIO
• Drop/mark from front
• PIE, Fq-PIE (Proportional Integrated controller Enhanced)
• CoDel, Fq-CoDel (Controlled Delay)
• AFD (Approximate Fair Dropping) [Used with elephant trap and computing the fair rate for each elephant]