Data center network

Data center network is the core infrastructure of cloud computing

Data center Topology Design

Representative solution: fat-tree

The fat-tree uses a three-layer topology for switch cascade. The access switch and the aggregation switch are divided into different clusters. Each access switch in the cluster is connected to each aggregation switch, each aggregation switch is connected to some core switches.

A typical fat-tree uses 1G commercial switch.

 

 

Data center network transmission protocol

The current data center network still uses a wide range of TCP data transmission, in certain circumstances, the TCP performance will drop sharply, a typical TCP incast.

The network link resources of the data center are much richer than those of the Internet. The traditional single-path transmission protocol cannot fully utilize the link resources, resulting in a waste of resources. Solution: multi-path TCP (mptcp) is introduced. mptcp establishes multiple connections for the same source and destination. The source end splits data into multiple copies and uses different connections for simultaneous transmission, each sub-Stream needs to maintain its own serial number and congestion window. The receiver needs to solve the disordered problem. mptcp also adopts the AIMD mechanism to maintain the congestion window, the addition of a Single-stream congestion window is related to the sum of all sub-stream congestion windows.

Customizes the transmission protocol for the data center. The Representative D3 protocol analyzes the data stream transmission size and completion time requirements, and allocates transmission rates for each stream display. When network resources are insufficient, the data streams that cannot be completed on time are actively disconnected.

 

Data center network