A common feature of the sonnet is the volta, or turn. As the English translation of this Italian word suggests, this is a turning point in the poem, marking a division between the first eight lines (octet) and the final six (sestet). In traditional sonnets, the octet presents some kind of problem that tends to be resolved in the sestet.

In "The Silken Tent," Frost presents us, using the conceit of a tent, with a portrait of a woman who appears in the first eight lines to be strong and secure in herself, standing firm and upright before the whole world. Yet in the final six lines, Frost shows us that the woman, like everyone else, is not completely independent. She is bound by ties of love to her fellow human beings. But they are not constraining in any way; she has freely chosen them and they give her life meaning and an even more secure foundation.

Yes, "The Silken Tent" is most definitely a sonnet--and I didn't realize that Robert Frost wrote sonnets!

The poem has all the elements of a Shakespearean sonnet:

a) 14 lines;

b) iambic pentameter: each line contains five repetitions that "move" in a dah-DAH-dah-DAH pattern;

c) the rhyme scheme is abab cdcd efef gg.

The poem consists of an extended metaphor, sometimes known as a "conceit." The poet's lover is compared to "silken tent" that has been set up in a field.

The tent's "supporting central cedar pole" seems to stand almost by itself, without the help of "any single cord."  This "signifies the sureness of the soul"--the lover's confident self-reliance.  The poem's original title was  “In Praise of Your Poise.”

The lover is independent but not aloof.  She is

loosely bound
By countless silken ties of love and thought
To every thing on earth

Although Frost uses the sonnet, a very old form of poetry, his language in the poem is simple and modern.