[ih] History question

[Craig Partridge]

Are you talking about multihoming a host or a network (host connected to
multiple networks, network connected to multiple providers).

For hosts, the issue appeared c. 1982/3 when Berkeley connected UCBVAX to
multiple Ethernets (I think for reliability reasons).  Around the same time
they also put IP router capability in the BSD networking code.  Berkeley
thought deeply about the issues but, for reasons unclear, didn't surface
their insights in the community until the late 1980s.  I remember Mike
Karels at an IETF Host Requirements meeting, going through a late draft of
the requirements document. At various points he said "you don't want to say
that as it breaks multihoming" and then had to explain to the room what the
issue was, because most of us were clueless.

For networks, the advent of NSFNET in 1987.  Suddenly you could be
connected to both ARPANET and NSFNET.  Also, because NSFNET was flakey,
people leased direct lines to peer institutions.  EGP promptly displayed
all its limitations -- there's a SIGCOMM '87 paper where Dave Mills and
Hans-Werner Braun presented interim solutions.

Craig

On Mon, Sep 7, 2026 at 11:38 AM John Day via Internet-history <
internet-history at elists.isoc.org> wrote:

> When and who brought the multihoming question to general discussion?
>
> When was it first recognized as an issue, even if there was no real
> discussion about a solution?
>
> Take care,
> John Day
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