On which interface is the E1 stream going?

Question

Computer networks

Good afternoon!
I searched the entire Internet, and I still can’t find what interface the E1 streams go through?
While there are assumptions:
— Ethernet;
— X.25;
— RS485.
Thanks in advance!

Answer 1

This is all because you don't know the OSI model. E1 - physical layer (as well as any multiplexing of the medium). Ethernet (well, ok, physical too), x.25 - link layer. These protocols can go through E1, but as a rule, ISDN (PRI) and SS7 (Pure OKS7) work through it today

Answer 2

https://ru.wikipedia.org/wiki/%D0%A6%D0%B8%D1%84%D...