The war story
Caveat:  MCI did VERY good job, not their fault.
MCI is contractor for both original vBNS and in 2002
brought up new DREN.  MCI had Verizon OC12 from
their pop to MAX for years, I suggested both share it.
With summer gige conversion, were unable to get
replacement gige line to their pop.  Decided keep
OC12atm and I installed their colo M10 to run TCCs.
Juniper and Andrea Reitzel tested in lab, worked
At midnight cut, vBNS TCCs failed, had to back out 5am.
Eventually had to loan MCI MAX on-site test routers.
Scott Robohn of Juniper found,needed old gige firmware
After another 4am-er got working, but tccs still touchy