Unification of east-west and north-south communications

In the overall architecture of microservices, there are two ways of east-west communication and north-south communication.The so-called east-west communication is to solve the communication and link management between the various microservices within the business; the north-south communication solves the problem of interaction between the cluster and the outside, including how the cluster services are provided to the outside world, and how the cluster can access the outside world.service.An analogy can be made here using concepts from traditional data communication.It can be considered that all the microservices that implement a business externally constitute a user-premises network: the east-west communication is responsible for the communication between various user terminals, and is responsible for introducing traffic to specific end users (corresponding to each microservice), and the specificThe access link of the terminal implements the function of the access network; the north-south communication is responsible for the interaction between an independent sub-network and the outside world, and carries all the traffic of the external interaction of the sub-network, which can be regarded as a backbone link and realizes the functions of the core network..

Service Mesh itself mainly focuses on the internal communication of east-west microservices.The characteristics of internal service communication of microservices are that the traffic is not too large, the QPS is generally not too high, and the overall performance requirements are not high.Reduce the business's attention to communication, and provide efficiency and stability support for the business.

From the perspective of communication characteristic requirements, there is a big difference between north-south communication and east-west communication, and north-south communication has two notable features.

• The first
  is that the traffic is very large, and it needs to carry all the external traffic of the entire business, so the QPS is very high, and it has very high performance requirements.

• The second
  is that the north-south communication is located between the business intranet and the external network.Protection and interception to prevent illegal and abnormal requests from attacking and affecting the intranet. Therefore, north-south communication has very high security requirements. It is necessary to continuously upgrade security prevention and control and security policies to protect the security and stability of intranet services.Therefore, for north-south communications, performance and security are the key words.

From a functional point of view, east-west communication and north-south communication provide similar capabilities: from a communication perspective, both traffic routing and load balancing need to be paid attention to;In terms of road governance, it is necessary to pay attention to governance features such as current limiting and downgrading.

From the above analysis, at the functional level, it is completely possible to realize the unification of east-west and north-south communications through Istio. Based on a set of communication infrastructure, the communication problems of these two dimensions can be solved.The main problem at present is performance. North-south communication has very high requirements on performance. Istio still has many problems to be solved in terms of performance, and cannot fully meet the needs of north-south communication.

Only from the data plane of Istio, Envoy is different from Nginx in design, and the performance of Envoy is also good enough. There are already many API gateway solutions based on Envoy.However, from the comprehensive data plane and control plane, Istio still has a lot of room for improvement in terms of performance. If it does not make certain adjustments in the architecture, it is still difficult for Istio to directly meet the performance requirements of north-south communication, east-west communication and north-south communication.There is still a long way to go to the complete convergence of communications.