Re: [TUHS] ARPAnrt, and the Unix epoch

[<ron@ronnatalie.com>]

Yes, it was a string of changes the network did on January 1.   A few years
earlier (1980?) they switched to long leaders on the IMPs on Jan 1.
This Jan 1 cutover meant that Mike Muuss and his staff (including me) at BRL
always had work to do over the holidays.
	
Shutting off NCP support was easy.   All NCP control messages traveled on
the IMP link 0.  IP traveled on link 155.

The IMPs were a gentle test for IP.   The virtual circuits were reliable and
flowed controlled even if the early TCPs were ornery.   A good IP
implementation did try to deal with the RFNM throttling.
The only real issue is the MTU mismatch between Ethernet and the IMP (1008
vs. 1500).

A while later, I noticed that the BRL Gateway (an early IP router) was
printing out messages that it was receiving link 0 messages.    Someone had
unblocked link 0, and there was some site out there was still some NCP host
trying to contact us (we had moved all our actual hosts OFF the outside imps
in favor of a pair of BRL Gateways).   Our interior network at that point
also comprised a handful of our own class B addressed IMPs.   An amusing
story there was as they were delivered and uncrated by the BBN guys I was
running around connecting up the data trunks and plugging hosts into them.
I sent a message to our BBN contact and told them that I had done this and I
got a long message back explaining it was impossible.    I'm sure glad I
didn't know it was impossible when I did it.    Later on, Joe Pistritto
managed to get the NOC protocol spec out of someone, and we wrote our own
NOC for the private IMP network.

Still, when they finally split the Arpanet from the Milnet, we got them to
do it on the first of the Fiscal Year (October) which fit our time schedule
at the labs a lot better.    Amusingly, there was one small hitch with the
"MAILBRIDGE" gateways that connected the two networks.    Apparently, BBN
forgot that we had the only IP router that was connected to the MILNET
(other than the MAILBRIDGES) and they screwed up that routing.