Dolyak signet and Glyph of Concentration Question.

Dolyak signet , if i cast this, it says i cannot be knocked down.
but if i am casting a 3 second spell, if enemy use hammer knock down on me, will my spell stopped casting(interrupted) even though im not knocked down?

Glyph of cencentration, it says my spell cannot be interuppted, if i cast 3 second cast time spell, if im knocked down, is my spell interuppted or still casting even though im knocked down?

If my impressions are correct, knockdown and interrupt are two different things, where knockdown will interrupt 100% of the time IF you are knocked down. Mantra of Concentration or Glyph of Concentration is more referring to mesmer skills like Leech Signet Power Drain Power Leak Power Spike or Airspec interrupts like Lightning Javelin, Ranger shots like Savage Shot and Distracting Shot.

Knockdown like Gale, Whirlwind(shouldn't concern spellcasters), hammer moves, earthquake etc should interrupt a caster even if they have glyph of conc or mantra of conc up.

And if my theory is right, if you have temp knockdown immunity you can still be interrupted via the standard ones.