The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
This document provides information on a frequently asked line coding question.
A. It does not matter what the coding is since the Cisco interface does not actually "see" the line. Our interface is the T3 DSU, which has to worry about the formatting and coding on the network line.
The vendor of the DSU (e.g. T3 Plus) might not support both. If the DSU supports both, Cbit is preferred for improved maintenance options.
Cbit is used when you want to use inband signaling for things like network management, similar to the Facility Data Link (FDL) of the T1. It is a 21-bit field. Cbit is part of the M13 frame, which is like the T1 frame, except it is called an M frame. The "13" represents a DS1 to DS3 multiplexer, hence M13.