What does North South mean in networking?

terminology

In context of networking I keep running into statements such as "east-west traffic is larger than north-south traffic". I have tried a bit of googling but have not been able to locate an authoritative answer to understand the origin of these terms.

  • What is the definition of north-south traffic?
  • What is the definition of east-west traffic?
  • What is the origin of these terms?

Best Answer

The terms are usually used in the context of data centers.

Generally speaking, "east-west" traffic refers to traffic within a data center -- i.e. server to server traffic. "North-south" traffic is client to server traffic, between the data center and the rest of the network (anything outside the data center).

I believe the terms have come into use from the way network diagrams are typically drawn, with servers or access switches spread out horizontally, and external connections at the top or bottom.

NORTH-SOUTH and EAST-WEST traffic is a network traffic flow pattern in the context of a data center. Let us consider the following example to understand these terms.

  • Example 
    • Let us say you are trying to access some web application via the browser. The web application is deployed in an application server which sits in some data center. In a multi tier architecture, a typical data center will not only contain the application server but also contains other servers such as load balancer, data base etc. along with the network components such as routers and switches. Let us say, the application server is front-ended by a load balancer.
    • When you access the web application, the following kinds of network flows happen..
      1. The network flow between the client (browser that sits out side of a data center) and the  load balancer (that sits in a data center)
      2. The network flow among the load balancer, application server, data base etc. which all sit with in a data center.
  • NORTH-SOUTH Traffic
    • In the above example, the first kind of network flow (i.e) the network flow between the client and the server is called the NORTH-SOUTH traffic. To put it simply, NORTH-SOUTH traffic is a server-client traffic.
  • EAST-WEST Traffic
    • In the above example, the second kind of network flow (i.e) the network flow among different servers with in a data center (or) the network flow among different data centers themselves is called EAST-WEST traffic. To put it simply, EAST-WEST traffic is a server-server traffic.
  • Now a days, the EAST-WEST traffic is much more than the NORTH-SOUTH traffic. This is especially true in todays BIG DATA eco systems such as HADOOP eco system etc. In HADOOP eco system, there will be so many servers that reside with in a data center to process the data using MAP-REDUCE. The traffic that flows among these servers will be much more than the traffic that flows between the client and the server.
  • You might be wondering, why they are named so ?
    • I think, the naming comes from the way the typical network diagrams are drawn to represent the network flow in and out of data center. In diagrams, usually the core network components are drawn at the top (NORTH) and the clients are drawn at the bottom (SOUTH). The different servers with in a data center are drawn in between horizontally (EAST-WEST).

Data centers are physical facilities designed to support your business applications, AI activities, file sharing, communications and collaboration services, and many more. They contain servers, storage systems, routers, firewalls, and other components which are crucial for the well functioning of the activities mentioned above.

Even in a simple activity such as trying to access a web application via an online browser, there is a client and a data center involved. The client (being any internet user) asks for information, which is obviously held in a data center containing other components as well (being your company digital assets). To perform the activity:

  • The client sends the request for access to the data center (communication between the data center and a component out of its boundary)
  • The components inside of the data center (application server, database, etc.) prepare the content to send to the client (communication between different components within the data center)

To better express which type of traffic flow pattern is the topic, there are two terms used in the field of security: east-west traffic and south-west traffic.

What does North South mean in networking?


East-West traffic

Any communication between two or more components of a data center, or even communication between different data centers, is referred to as east-west traffic. For instance, east-west traffic occurs when routers within a data center exchange table information, or when a LAN client communicates with a server in the data center.

Because the usage of virtual systems has grown extensively, and because organizations now prefer private cloud infrastructure more and more, east-west traffic volumes have increased drastically. Nowadays there are many functions and services performed virtually, instead of how they used to – on physical hardware. This can help with many issues, however, the traffic on the network has increased as well, and as a result, there can be latency which impacts network performance.


North-South traffic

Any communication between components of a data center and another system, which is physically out of the boundary of the data center, is referred to as north-south traffic. In simpler words, it is any traffic coming to a data center, or going out of it to another system. That other system can be simply a client requesting access to a web application (as mentioned above).

Traffic coming into the data center through a firewall or other perimeter network device – is referred to as southbound traffic. The opposite of it, traffic going out of the data center is referred to as northbound.

North-south traffic usually includes queries, commands, and data in general, being requested from a data center or stored in one.


Securing your network traffic

Traffic can not be trusted just because it comes from within your physical boundaries. Either coming from within your assets (east-west), or from outside through a perimeter network device (north-south), Traffic is trusted only when all the services are secure.

North-South traffic is usually considered as more dangerous traffic because it comes from outside the perimeter, and that is a logical conclusion. That is why many security solutions focus more on it. However, considering that inside traffic makes the largest part of the whole traffic, it is more than possible that malicious activities can end up going from one service to another.


Why is East-West traffic security important?

Although east-west traffic is the biggest part of all traffic, being inside the physical boundaries of a data center, has led to many organizations considering it as secure and not using security controls to monitor it.

A possible reason why east-west traffic is considered secure is that it is assumed that network firewalls don’t let any nefarious function inside the network. And that is their purpose, to block unauthorized content from getting into the network.

Yet, threat actors find a solution for their actions long before companies think about securing the traffic inside the network. New malware keeps coming up, and as long as security experts do not have the right patch for a vulnerability (in time) threat actors can compromise the systems. After malware gets into the network, firewalls can not do anything about it. Then, as long as the company “trusts” its assets without properly evaluating them, threat actors get to be persistent in their nefarious activities. This includes surveilling the network, getting access to confidential data, and in general causing trouble to business operations, which may, in time, cause a bad reputation.

Insider threats can cause bigger trouble for a company since they are harder to catch and less suspected in the first place – the same goes for inside traffic threats.


What can SOCRadar do about it?

SOCRadar provides proactive protection to companies by tracking every change and risk posed to digital assets. Moreover, it provides actionable insights into future cybersecurity threats with a big data-powered threat investigation module. It assists in searching deeper context, real-time threat investigation, and analysis. Companies can track adversaries to get up-to-date information about various TTPs or see all the vulnerabilities that are being leveraged by those threat actors.

SOCRadar also continuously monitors your attack surface, and besides all, informs in case a vulnerability is found in any of your assets. This way, even if the firewall misses a malware, SOCRadar will be there to help you mitigate the risk before you east-west traffic gets compromised by a threat actor.


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attack surface managementCTI Fundamentalsnetwork traffic security

What is North

North-south traffic refers to client-to-server traffic that moves between the data center and the rest of the network (i.e., a location outside of the data center).

What is North

Any communication between components of a data center and another system, which is physically out of the boundary of the data center, is referred to as north-south traffic. In simpler words, it is any traffic coming to a data center, or going out of it to another system.

What is North

As a form of traffic control, network segmentation is considered to be north-south—meaning that any users, applications or devices authenticated into a designated network zone of the network are trusted.

What is East

East-west traffic, in a networking context, is the transfer of data packets from server to server within a data center. The term east-west for this type of traffic comes from network diagram drawings that usually depict local area network (LAN) traffic horizontally.