NFV helps operators launch new services faster and grow their networks without constantly investing in new hardware. Users, however, care about something much simpler. They want services to be fast, stable, and available when needed.
The real challenges often appear after deployment. Performance depends on more than server capacity alone. Other workloads sharing the same infrastructure, additional virtualization layers, and interactions between different network functions can all affect how a VNF performs. Many of these factors played a much smaller role in traditional network environments.
One Overloaded VNF Drags the Whole Network Down
In NFV, several network functions often run on the same server. When traffic is calm, there are no issues, and everything works as expected.
But during a sudden surge of users, things change. A big stream or an online event comes in, and one function starts using a lot of resources. As a result, other functions on the same server also start to slow down.
Nothing literally “breaks”. The server does not crash, and there are no errors. But latency increases, services respond more slowly, and users are the first to notice that something is off.
To avoid learning about the problem through complaints, operators check how VNFs behave under real load using application performance testing. This shows how the system behaves in stress conditions, not just in test numbers.
Latency That Builds Up Quietly
In NFV, latency rarely appears in an obvious way right away. At the level of an individual component, everything looks normal.
But every packet passes through additional processing layers: hypervisors, virtual switches, management systems, and orchestration platforms. Each of these stages adds a small amount of delay. On its own, this does not cause problems, but in real traffic, these delays accumulate.
For example, in a VoIP service for a contact center, everything works normally at first. Over time, users start noticing short delays in calls. Then the number of complaints increases, and this starts affecting service quality and SLA.
In such situations, don't look at average performance values only. Even a few milliseconds of delay can affect user experience more than it might seem at first.
Too Many Small Packets Slow Everything Down
Many teams focus only on traffic volume. But for network functions, that is not the main factor. What matters more is how many packets the system has to process.
Two flows can carry the same amount of data. But one is made up of large packets, while the other consists of a large number of small ones. And for the CPU, this creates very different workloads.
That is why problems often appear in EPC, IMS, or 5G Core environments. When traffic increases, the server spends resources not on data transfer but on processing each packet. As a result, throughput may look normal, but services start to slow down.
When CPU and Memory Are Too Far Apart
Modern servers are strong and capable, but they don’t handle all parts of their system in the same way. Inside a physical server, the processor and memory are split into different areas, often known as NUMA nodes. If a virtual network function (VNF) has its processing tasks in one area but its memory in another, the system has to do extra work to move information between these two places. This slows things down quietly, creating a hidden slowdown in processing.
Even if basic checks show that the server has enough processing power and memory available, the virtual network device (VNF) can still run slowly and lose data packets. It might seem like there’s not enough hardware, but the real problem is where the VNF has been set up. To fix this, the resources need to be carefully organized and kept in the same area, which makes setting up these systems more complicated.
Service Chains Slow Things Down More Than They Look
On diagrams, service chaining looks simple. Traffic goes through a firewall, load balancer, security services, and other functions. Each one does its own part of the work. In reality, every step adds latency. One element is barely noticeable. But when there are many of them, the delay starts to build up.
The problem is that this is not always visible right away. The user sees a slow application. The team checks the server and finds nothing critical. But the cause can be one of the VNFs somewhere earlier in the chain.
The Scaling Trap: Why More Resources Don’t Always Help
Performance usually drops due to simple reasons:
- CPU overload during traffic peaks
- High number of packets
- Long service chains
- Poor VNF placement
- Overloaded virtual switches
- Configuration mistakes after scaling
Because of this, adding more resources does not always fix the issue. Sometimes it only delays it.
Why Performance Is Hard to Control in NFV
In NFV, performance problems are hard to find quickly because they do not appear in one place – they show up in different parts of the system at the same time. And even if the service is getting slower, servers still look normal.
Standard monitoring metrics like CPU usage, RAM (News - Alert), network traffic, and basic errors do not show the full picture because each component only reflects its own part of the system. That’s why Telecom testing is used. It shows how the whole system really behaves under load and where delays actually start.
Final Impact of NFV Complexity
Network functions virtualization (NFV) was created to make managing networks more flexible and quick. However, instead of relying on physical equipment, it relies heavily on complex software, which can be difficult to manage. The problem is that small issues, like a tiny delay or a slight shortage of resources, might seem minor at first. But under heavy usage, these problems can quickly spread and build up. It brings noticeable slowdowns or problems for users long before any warning signs appear with traditional monitoring tools.
Since regular monitoring only checks specific numbers, users often struggle to find the real problems, while customers quietly deal with calls dropping or videos stopping to load.
To really understand and succeed with NFV, network operators need to stop focusing only on separate parts and instead see the entire network as one connected system. This means moving away from just watching individual pieces and instead actively checking how the whole system performs together. By creating realistic tests that mimic actual busy conditions and seeing how all the virtual components work with the underlying hardware, experts can find hidden problems early, before they cause any trouble for the business.
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About the author:
Sandra Parker is the Head of Business Development and a member of the Advisory Board at TestFort. With over ten years of experience in the IT industry, she specializes in supporting organizations to accelerate their growth through digital transformation, offering customized software development solutions and implementing the latest quality assurance practices. Sandra is a technology enthusiast dedicated to staying informed about emerging trends and advancements in digital innovation.
