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What Is DPI In Networking?

DPI in networking


DPI stands for Deep Packet Inspection. DPI in networking is an advancement in technology and a method to examine and manage network traffic. Earlier we had conventional packet filtering which was used to examine packet headers. DPI is more advanced as it not only examines packet headers but also detects the same. 

DPI is a form of packet filtering that locates, identifies, classifies as well as reroutes or blocks packets of specific data. It functions at the application layer of the Open Systems Interconnection (OSI) reference model. Read on to learn how DPI functions, what its different techniques are, what its uses and limitations are, and how it is better than conventional packet filtering.

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A managed security services in cybersecurity, network & infra security, & cloud security, CubixTech Integration is headquartered in Pune with a Pan-India & Global presence & 70% of Fortune 100 companies as customers. We have global deployments in over 18 countries with partnerships with more than 10 Best global IT solutions companies. We are also F5 USA’s no. 1 implementation & professional services partner in India.

Working on Deep Packet Inspection

DPI works by examining the contents of packets that pass through a given checkpoint. Based on the contents and the assigned rules of an enterprise/network manager/internet service provider, the DPI makes real-time decisions of whether or not to let them pass.

Deep packet inspection has come up as a new technology for deeper inspections of large volumes of traffic, that too, in real time. Today, it cannot just check the packet headers, but also their data through advanced inspections.

DPI in networking can even identify the particular application or service that sent a specific message. 

Deep Packet Inspection Techniques

There are three main techniques to use DPI. They can be briefed as follows:

  • Pattern or signature matching: Each packet is analyzed by a firewall with IDS capability against a database of known network attacks. Specific patterns are looked for and those found malicious are blocked. This approach, however, carries one disadvantage – it requires the signatures to be updated regularly. Moreover, it works only against known attacks and threats. Signature updates are necessary for the firewall to detect threats and protect the network, as new threats are discovered daily.

  • Protocol anomaly: This method is also used by firewalls with an IDS, but does not carry the same limitation. It follows a default deny approach. The firewall decides which content or traffic should be allowed depending on protocol definitions, and does not require signature matching. It thus protects the network from unknown attacks without the inherent weakness of pattern or signature matching. 

  • Intrusion prevention system (IPS): Finally, we have the IPS solutions. They prevent malicious packets from getting delivered depending on their contents and thus block detected attacks in real time. This approach also carries one limitation, that is, it requires regular updating of the cyberattack database with information about new threats.

Uses and Applications of DPI

Deep packet inspection (DPI) is primarily used by the following:

  • Firewalls, that include an intrusion detection system feature

  • Standalone IDSes that intend to detect attacks and protect the network

Here’s an overview of how DPI is being used:

  • As a network security tool: Deep packet inspection can be used to detect as well as intercept different forms of malicious traffic such as viruses, spyware, and worms. It can even detect intrusion attempts.

  • For more nefarious activities: DPI in networking can be applied to nefarious activities like eavesdropping and state-sponsored censorship.

  • For network management: Using DPI, content policy enforcement can be done to stop leaks. It can also be applied for streamlining or modifying the flow of traffic through a network as per specific cases.

  • DPI in networking to throttle data transfers: Moreover, deep packet inspection can help prevent peer-to-peer abuse, thereby improving network performance.

  • Identify the originator and the recipient: DPI also helps identify the origin of a specific content and its recipient.

To exemplify, DPI can be used to route a message or a packet marked as high-priority to its destination ahead of the other less important and lower-priority messages. 

DPI is preferred by many these days due to its array of benefits and applications. However, there are some associated limitations too. Read further to know what the disadvantages of using deep packet inspection are.

Drawbacks of Deep Packet Inspection

DPI has emerged as a powerful tool for network protection. However, there is a negative side to every positive aspect, and so is true for DPI. There are three main limitations of deep packet inspection:

  • Can be exploited to facilitate attacks: As discussed, DPI is proving great in protecting against existing vulnerabilities. However, it can also lead to the creation of new ones. It is effective against denial-of-service attacks, buffer overflow attacks as well as various types of malware. However, at the same time, DPI can be misused to attempt attacks in the same categories. 


  • Additional complexity: Being a new and more advanced technology, the deep packet inspection feature also comes with a burden on the technical experts. It increases the need to revise and update it periodically, thereby putting more burden on the administrative security teams. DPI in networking thus adds to the unwieldy nature of existing firewalls and many other security-related software.

  • Reduced network speed and performance: Last, deep packet inspection can hamper the speed of the network by creating bottlenecks for data decryption and inline inspection. This further increases the burden on the firewall processors.


DPI has its own set of limitations. But that has not stopped some network administrators from embracing the technology of DPI in networking to manage the increased volume, complexity, and frequency of internet-related threats, despite the given drawbacks. Deep packet inspection has become a powerful aspect of the network security ecosystem.

With DPI-related services by CubixTech Integration, you get to secure your business efficiently as well as manage your risks effectively.


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