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50ms is fast? You'd drop sevral packets I'd guess.

easily survivable. but will bgp flap?

sure, if your BGP holdtime is less than 50ms :-) On a series note, GR253 specs it at 50ms. Convergence in regional rings, however, is often more a function of propagation delay, and more realistically, with larger-than-probably-should-be rings expect times more around the 100ms range. As for how it'd look on your router, assuming a trunk failure, you'd likely see a bunch of CRC or frame errors on the interface, and an array of SONET errors on the controller. Then, presumably, you'd see a bit more latency on the connection while running on the usually less-optimally-routed protect path. Of course, more interesting than presumably transparent trunk failures in relation to SONET protection, are trib failures with inter-router APS on the trib side. This requires a bit more attention to detail (speaking from experience). -danny