Re:How Do Routers Work, Really?
by Cerium on Thursday September 10, 2020 @04:07PM
(#24436030)
The IP stack has the concept of layers, which function as abstractions that hide the implementation of lower layers from the upper layers. Layer 2 (L2) is the physical link layer - it only cares about getting a packet between two devices. Layer 3 (L3) is where IP addresses live. As the article describes a router has functionality to send a packet towards its final destination as well as get it between ports.
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> The IP stack has the concept of layers, which function as abstractions that hide the implementation of lower layers from the upper layers
Correction: the network stack has layers, where IP is one of them, near the top.
Which is why most software targets IP. It’s a good abstraction and it’s portable.
Re:How Do Routers Work, Really?
by cameronh90 on Thursday September 10, 2020 @05:51PM
(#24436918)
GP may be referring to the "TCP/IP model" which does indeed define the layers used in common parlance. This model has 4 layers in contrast to the OSI model's 7 layers. The TCP/IP model is closer to how most real life network stack implementations are defined.
Arguably even this layering system is too rigid for reality but it's a decent model. See RFC 3439 section 3.
L1 is (naturally) physical. L2 is data link.