Re: [9fans] datakit

[geoff@collyer.net]

My experience with datakit was limited, but from what I understand
(and can remember) the advantages were:

• it provided some protection against snooping and meddling with data
in transit by running connections directly from the network controller
(kept in a locked closet) to the hosts and by not being a broadcast
medium, and by securing the connections between network controllers.

• partly as a consequence, when a call arrived and the datakit
controller said that it was from a particular destination, you could
believe it.

• when you placed a call, you handed a dial string like
`nj/astro/helix!uucp' to the datakit controller and it returned with
either an error message or a live connection.  You could also tell
that controller if you expected to need a lot of bandwidth (e.g.  for
file transfer) or not, and it would try to reserve bandwidth along the
route.  So no need for DHCP, ARP, RARP, BOOTP, sockets, sockaddrs,
inaddrs, etc., etc.

• IP, UDP and TCP were subsumed by a supposedly-simple protocol, URP.
I believe datakit was a reliable network, so you didn't need an extra
layer of protocol such as TCP.

• datakit was available in a variety of speeds and could be run great
distances, including cross-country.

I'm less familiar with the drawbacks, though I have heard some of the
moaning over the years, so I'll give a try:

• datakit hardware, particularly the controllers, was expensive.

• it was a centrally-managed network, arguably less open to ad-hocery
than ethernets built from switches and routers.  Some may see this as
a disadvantage, though it enabled many of the advantages named above.

• some of the host interfaces (e.g., Vax ones) were reputedly
painfully slower than the network itself.

My dislike for one-problem-one-protocol-one-RFC is largely one of
taste and conserving energy for more important things.  Do we really
need over 3,700 RFCs to make our networks work?  I don't have a strong
opinion about the end-to-end principle or various other IETF dogma.
We could certainly have done worse, OSI being the scariest of the
possible disasters (and it's not quite dead yet, it keeps popping up
in places like LDAP!).

Are you sure you don't have Datakit in your central offices or
long-distance equipment?