On Shakespeare" is a poem written by John Milton. This poem, also known as Song On Shakespeare, was written in 1630. There is also a revised version of the poem written two years later which is entirely different. The 1632 version was written more as an epitaph and sometimes called "On the University Carrier who".
This poem is a sixteen line single stanza. It is written in the rhyme scheme AABBCDDEEFFGGHH. It is also written in iambic pentameter. Thus, this can be said to be written in heroic couplets. This is indeed a salute to Shakespeare by writing in iambic pentameter. However, I think, Milton should have went ahead and made it an Elizabethan sonnet instead.