Physical connectors for x.25, frame relay, ATM

[Sam Brynes]

I remember learning about frame relay when studying for my CCNA, and maybe a sentence or two touched on X.25, but I was wondering what the physical connections for X.25, frame relay, and ATM looked like? X.25 pre-dates the OSI model, and frame relay and ATM specifies layer 1 and layer 2.

[Georg Pauwen]

Hello,

X.25 and Frame Relay typically required a DB-25 or V-35 connector (check the link below). ATM in the very early days had a specification for 155Mbps over twisted pair cable, but typically, fiber was used.

https://www.sangoma.com/data-wan/rs232-rs422-and-v-35-interfaces/