Let $(K,v)$ be a henselian valued field ($v$ is a henselian valuation in the sense of Krull valuation on a field $K$). Consider again $v$ for the unique extension of $v$ to every algebraic extension of $K$. Denote $R_{K}$ and $G_{K}$, respectively, as the residue class field and the value group of $(K,v)$. I know the following definition for a totally ramified extension of $(K,v)$ (see the paper: https://s2p.studylib.net/store/data/010829939.pdf?k=AwAAAXxMzjzRAAACWC7g_a_njYYtyq6gWbBwBW9X4CIh). "Let $L/K$ be an algebraic extension. The composite $T/K$ of all unramified subextensions is called the maximal unramified subextension of $L/K$. A finite extension $L/K$ is called totally (or purely) ramified if $K=T$, i.e., if no subextension of $L/K$ except $K$ itself is unramified over $K$."
I would like to know other characterizations of this definition. In a totally ramified extension $L/K$, what are the relations among the degree of the extension $[L:K]$, the residue class fields $R_{K}$ and $R_{L}$, and the value groups $G_{K}$ and $G_{L}$? Is such an extension necessarily defectless? Can we say that $L/K$ is totally ramified if and only if $[L:K]=[G_{L}:G_{K}]$ (i.e., $L/K$ is defectless and the degree of the extension is equal to its ramification index)?
Thanks for any help!