ATM = Apologies To Muse?

There once was a net that ran ATM
Its packets were all fixed size then.
Its circuits were virtual,
paths short, fixed and bursty, all
signaled and stat muxed and shaped again.

There once was a LAN that ran ATM
the Cambridge ring was one of them
cell sizes so small
no header at all
I believe that finally it sank in a fen