Hi,
1) Do companies nowadays still use Frame relay to connect different branches over leased lines?
Yes, some companies still do. Frame relay is not as popular as it used to be 8 or 10 years ago specially in the U.S. It is so much faster and cheaper to get an Ethernet (50Mb, 100Mb, Gig, etc..) than using Frame Relay.
2) Which other methods are used to connect two or more branches? (except Site-to-Site VPN)rnet
Side-to-side VPN, Ethernet, DS3, some point-to-point T1s.
3) It is hard for me to understand the cabling: I have a cisco router which I connect via serial cable with the CSU/DSU.
The CSU/DSU is connected with the Frame Relay Switch from the ISP? Which cable is used between the CSU/DSU and the FRSW?
If I remember correctly, its copper.
Where is the CSU/DSU located? Is this right:
The newer Cisco routers have CSU/DSU build into the WIC (T1 card). So you don't need any extra cable. You just need a copper RJ45 that connects your router back to the provider. The old 2500, 2600 routers did not have build in CSU/DSUs and so you had to use an external CSU/DSU.
HTH
