Massive reconvergence event in their network, causing edge router bgp sessions to bounce (due to cpu). Right now all their big peers are shutting down sessions with them to give level3s network the ability to reconverge. Prefixes announced to 3356 are frozen on their route reflectors and not getting withdrawn.
Edit: if you are a Level3 customer shut your sessions down to them.
Edit: if you are a Level3 customer shut your sessions down to them.