In this episode of the backend engineering show I go through and discuss the Homa Protocol paper which attempts to replace TCP as a protocol in the data centers. I learned a lot from this paper, I have my criticisms of certain aspects, timestamps for topics discussed below.

It appears there is a path to replace TCP in the datacenter and professor John tries to explain this path.

Referenced materials mentioned in the episode

Overview paper

https://web.stanford.edu/~ouster/cgi-bin/papers/replaceTcp.pdf

Homa 2018 paper (Details)

https://people.csail.mit.edu/alizadeh/papers/homa-sigcomm18.pdf

NIC Offloading in Linux

https://en.wikipedia.org/wiki/TCP_offload_engine#Support_in_Linux

Curl disabling Nigel Algo

https://github.com/curl/curl/commit/4732ca5724072f132876f520c8f02c7c5b654d9

0:00 Intro

3:00 The nature of networking data center

5:30 TCP Segments

7:30 There is no “Request” in TCP

12:00 What so unique about Data centers?

14:00 Message Throughput vs Data throughput

18:25 Congestion Control

22:38 Homa’s Congestion Control

25:00 Server Core Load Balancing

28:30 NIC offloading

30:00 Everything Wrong about TCP

37:00 Why not QUIC?

40:00 Limitation of Streaming

44:10 Load Balancing Stream Reading

47:15 Can we treat Segments as Messages?

51:00 Dispatching Messages is Easier

53:00 Connection Orientation

1:00:00 Sender Driven Congestion Control

1:03:00 In Order Packet Delivery

1:07:00 DCTCP

1:08:30 Homa is Message Based

1:11:00 Home is Connection Less

1:12:00 Receiver Driven Congestion Control

1:15:19 Out of Order Packets

1:16:20 Homa API is not Compatible with TCP

1:17:40 Will Homa come to HTTP?

1:18:45 Conclusion

Replacing TCP for the Datacenter - Discussing the Homa paper

The Backend Engineering Show with Hussein Nasser