Question about SDSL csu/dsu, is it a layer 1 or layer 2 device?

[rleung2001]

I checked the following link.

http://www.cisco.com/en/US/tech/tk1330/tsd_technology_support_technical_reference_chapter09186a0080759754.html

T1 CSU/DSU and modem are layer 1 device

NIC is a layer 2 device, but SDSL module card requires an external modem.

What layer device ADSL and SDSL module, layer 1 or 2 device?

[JORGE RODRIGUEZ · Accepted solution]

ADSL, SDSL, DSL are layer 1 , you may also find more detailed information at the ITU-T link bellow.

http://www.dslforum.org/aboutdsl/adsl_tutorial.html

http://www.itu.int/ITU-T/

Rgds

Jorge