Could someone provide some real world scenerios to understand the role played by session layer in OSI model.

Presentation Layer handles zip&unzip etc. Similarly what does session layer handle?

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    Sad that this is closed, because the referred question is more general and doesn't answer this one. Commented Dec 18, 2020 at 3:08
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    Real world scenario using the session layer: file transfer with a temporary network outage, or the application restarts during transfer. More generally, how to pick up where you left off. The thing is, it turns out that it's best not to let the "communications stack" do that, but rather to use libraries/objects/application-elements to do it, so modern solutions exist but aren't organized into a "layer." Commented Dec 18, 2020 at 3:12

1 Answer 1


The session layer isn't (really) used in the real world. You can regard it as a conceptual model or as a sublayer in the real-world application layer but it simply doesn't exist.

Sessions are present in many web applications, but most often the session handling is woven into the application, without any distinct sublayer.

The presentation layer is very similar. Some application-layer protocols have a somewhat well-defined presentation sublayer (e.g. HTML, or RFC 5322 for SMTP/RFC 5321), but there really isn't any standard in practice.

  • Thanks. Further, which layer handles SSL/TLS? application layer or presentation layers?
    – samshers
    Commented Jul 31, 2020 at 14:00
  • See if this question and answer helps you.
    – Ron Trunk
    Commented Jul 31, 2020 at 14:08
  • @samshers That's a commonly asked question and there's no definite answer to it. It's in between transport and application layers, but it's neither session nor presentation layer (although some argue for either)
    – Zac67
    Commented Jul 31, 2020 at 17:44

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