session-based routingTraditionally several current network scenarios are based on packet routing, but to reduce the network complexity, a concept has appeared on the market: session-based routing. This is due to theThe evolution of the network, which has reached a point where the complexity is continuously growing, and the elements involved are more and more expensive.


A session is not a new concept, because many of the communication protocols used nowadays in the network are based on them. For instance: HTTP/HTTPS session, SIP session… but the disruption of this session-based routing technology consists in including it in the routing devices.

  • Although a session can have different definitions, it’s possible to define a session as a temporary connection between two endpoints for communicating information. However, whatever definition is used, there are some common characteristics which can be applied all the session definitions:
  • A signal to establish the connection (and very often a signal to end it) is required.
  • The communication is bidirectional between both end-points. The session is compounded by two flows, one in each direction.
  • The status of the connection (established, ended…) must be announced.
  • Each session must be unique.

Apart from reducing the network complexity, there are many benefits of using session-based routing instead of packets to route the traffic, which are mentioned below:

  • Dynamic routing decision based on the distributed knowledge of the service: a session knows the status of the communication from the source of the traffic to the end-point, so it knows the status of all the communication path.
  • Dynamic path selection: the sessions can be balanced dynamically to different WANs, and instead of using one link simultaneously to send the traffic, it’s possible to use two or several links to send the traffic of one session, increasing the throughput of a specific application.
  • Secure and agile network: the devices can understand and enforce policies in the network providing a higher level of security.

In conclusion, the session-based routing technology is closer to an “application centric” network approach, which is the target for the next generation networks, than is the traditional packet routing. In the next generation network, the key measuring points should be the real user experience of an application, as this is what will guarantee the correct performance of an application. For that, the network must be focused on applications, that are more related to sessions than packets.

The main objectives of this session-based routing technology are:

  • Increase the reliability and performance of the network, which is key for new applications related to IoT, video or virtual reality.
  • Reduce the complexity of the middleboxes as firewalls and load balancers to lower network costs.

To sum up, session-based routing is a reality today, and an important growth in the implementation of new devices based on this technology is expected. Indeed, in Teldat we definitely believe in the future of session-based routing and its role in the application centric market and how session-based routing complements SD-WAN technology. Hence an important part of Teldat R&D is developing technology in this area.


About the author

Carlos GomezCarlos Gomez
Telecommunications Engineer, Business Line Manager working for the SD-WAN line within the Product Marketing Department.  


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