The Host-to-Host Layer

The host-to-host layer of the TCP/IP protocol is aptly named. Whereas the internet layer is responsible for the logical paths between networks, the host-to-host layer is responsible for the full logical path between two hosts on disparate networks[12]. From another viewpoint, the host-to-host layer is an interface to the lower layers of the protocol suite, freeing applications from any concern about how their data is actually being delivered.

[12] Similarly, it can be said that the equivalent functions of the OSI session layer, residing above the transport layer, provide a logical, end-to-end path between two applications across an internetwork.

An analogy to this service is a corporate mailroom. A package may be given ...

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