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* [TUHS] BerkNet
@ 2014-11-26 18:49 Noel Chiappa
  2014-11-26 20:16 ` Clem Cole
  2014-11-26 23:33 ` Jesus Cea
  0 siblings, 2 replies; 15+ messages in thread
From: Noel Chiappa @ 2014-11-26 18:49 UTC (permalink / raw)


    > From: Clem Cole

A few comments on aspects I know something of:


    > BTW: the Arpanet was not much better at the time

The people at BBN might disagree with you... :-)

But seriously, throughout its life, the ARPANET had 'load-dependent routing',
i.e. paths were adjusted not just in response to links going up or down, but
depending on load (so that traffic would avoid loaded links).

The first attempt at this (basically a Destination-Vector algorithm, i.e. like
RIP but with non-static per-hop costs) didn't work too well, for reasons I
won't get into unless anyone cares. The replacement, the first Link-State
routing algorithm, worked much, much, better; but it still had minor issues

damping fixed most of those too).


    > DH11's which were a full "system unit"

Actually, two; they were double (9-slot, I guess?) backplanes.


    > The MIT guys did ARP for ChaosNet which quickly migrated down the street
    > to BBN for the 4.1 IP stack.

Actually, ARP was jointly designed by David Plummer and I for use on both
TCP/IP and CHAOS (which is why it has that whole multi-protocol thing going);
we added the multi-hardware thing because, well, we'd gone half-way to making
it totally general by adding multi-protocol support, so why stop there?

As soon as it was done it was used on a variety of IP-speaking MIT machines
that were connected to a 10MBit Ethernet; I don't recall them all, but one
kind was the MIT C Gateway multi-protocol routers.


    > Hey it worked just fine at the time.

For some definition of 'work'! (Memories of wrapping protocol A inside
protocol B, because some intervening router/link didn't support protocol A,
only B...)

     Noel



^ permalink raw reply	[flat|nested] 15+ messages in thread
* [TUHS] BerkNet
@ 2014-11-27 14:38 Noel Chiappa
  2014-11-29 16:34 ` Clem Cole
  0 siblings, 1 reply; 15+ messages in thread
From: Noel Chiappa @ 2014-11-27 14:38 UTC (permalink / raw)


    > From: jnc at mercury.lcs.mit.edu (Noel Chiappa)

    > The replacement, the first Link-State routing algorithm, worked much,
    > much, better; but it still had minor issues
    >
    > damping fixed most of those too).

Oop, the editor 'ate' a line there (or, rather the editor's operator spaced
out :-): it should say "it still had minor issues, such as oscillation
between two equal-cost paths, with the traffic 'chasing itself' from path to
path; proper damping fixed most of those too".


    > I always give Dave Clark credit (what I call "Clark's Observation") for
    > the most powerful part of the replacement for the ARPAnet - aka the
    > idea of a network of network.

Not sure exactly what you're referring to here (the concept of an internet
as a collection of networks seems to have occurred to a number of people,
see the Internet Working Group notes from the early 70s).

    > Dave once quipped: "Why does a change at CMU have to affect MIT?"

Subnets (which first appeared at MIT, due to our, ah, fractured
infrastructure) again were an idea which occurred to a number of people all
at the same time; in part because MIT's CHAOSNET already had a collection of
subnets (the term may in fact come from CHAOSNET, I'd have to check) inside
MIT.

    > I've forgotten what we did at CMU at the time, but I remember the MIT
    > folk were not happy about it.

I used to know the answer to that, but I've forgotten what it was! I have this
bit set that CMU did something sui generis, not plain ARP sub-netting, but I
just can't remember the details! (Quick Google search...) Ah, I see, it's
described in RFC-917 - it's ARP sub-netting, but instead of the first-hop
router answering the ARP based on its subnet routing tables, it did something
where ARP requests were flooded across the entire network.

No wonder we disapproved! :-)


    > Thought, didn't you guys have the 3Mbit stuff like we did at CMU and
    > UCB first?

MIT, CMU and Stanford all got the 3Mbit Ethernet at about the same time, as
part of the same university donation scheme. (I don't recall UCB being part
of that - maybe they got it later?)

The donation included a couple of UNIBUS 3Mbit Ethernet cards (a hex card,
IIRC) the first 3MB connections at MIT were i) kludged into one of the MIT-AI
front-end 11's (I forget the details, but I know it just translated CHAOS
protocol packets into EFTP so they could print things on the Dover laser
printer), and ii) a total kludge I whipped up which could forward IP packets
back and forth between the 3M Ethernet, and the other MIT IP-speaking LANs.
(It was written in MACRO-11, and with N interfaces, it used hairy macro
expansions to create separate code for each of all 'N^2' possible forwarding
paths!) Dave Clark did the Alto TCP/IP implementation (which was used to
create a TFTP->EFTP translating spooler for IP access to the Dover).

I can give you the exact data, if you care, because Dave Clark and I had
a competition to see who could be done first, and the judge (Karen Sollins)
declared it a draw, and I still have the certificate! :-)

	Noel



^ permalink raw reply	[flat|nested] 15+ messages in thread
* [TUHS] 2.10
@ 2014-11-21  5:46 Clem Cole
  2014-11-21  6:07 ` Cory Smelosky
  0 siblings, 1 reply; 15+ messages in thread
From: Clem Cole @ 2014-11-21  5:46 UTC (permalink / raw)


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On Thu, Nov 20, 2014 at 10:55 PM, Cory Smelosky <b4 at gewt.net> wrote:

> Well, 2.10 has SLIP,

​SLIP means you still need the IP stack
​ (serial-line-ip)​
.  It ​
​just replaces an ethernet driver with a serial port.




> but it'd certainly be easier to implement a simple userland tool to talk
> to a frontend!


​Actually there was tool that was almost all in userland to support
multiple sessions over single serial line between a Macs a UNIX system.  My
memory is that it used Chesson's multiplexer (mpx) which is part of stock
V7 (his is pre-select system call).​  I wish I could remember the name of
that program.  But I bet it or something like it could be repurposed pretty
quickly to talk to a frontend micro.

Biggest issue is interrupt overhead on serial ports on the 11.   If this is
real HW, see you can find a real DEC DH or better yet - an Able DH/DM.  DH
style interfaces will be a huge difference over DL's or DZs.  DZs were pigs
on Vaxen and on an 11 a line at 19.2K continuous could kill it.

BTW:  I thought of another option.  It's not telnet or ftp, but if your
desire is move files back and forth without having to use a common physical
media and sneaker-net, BSD 2x should have the BerkNET code in it.   That
will run on an serial line - although my previous comment about the type of
interface can matter from a performance standpoint.

Clem
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^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2014-11-29 16:39 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-11-26 18:49 [TUHS] BerkNet Noel Chiappa
2014-11-26 20:16 ` Clem Cole
2014-11-27 20:40   ` Dave Horsfall
2014-11-29 16:39     ` Clem Cole
2014-11-26 23:33 ` Jesus Cea
  -- strict thread matches above, loose matches on Subject: below --
2014-11-27 14:38 Noel Chiappa
2014-11-29 16:34 ` Clem Cole
2014-11-21  5:46 [TUHS] 2.10 Clem Cole
2014-11-21  6:07 ` Cory Smelosky
2014-11-26  6:28   ` [TUHS] BerkNet Erik E. Fair
2014-11-26  6:48     ` Cory Smelosky
2014-11-27 16:42       ` Mary Ann Horton
2014-11-29 16:38         ` Clem Cole
2014-11-26 18:24     ` Clem Cole
2014-11-26 18:35       ` Dan Cross
2014-11-26 20:03         ` Clem Cole
2014-11-26 18:26     ` Dave Horsfall

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