[ih] When did "32" bits for IP register as "not enough"?

[Joe Touch]

> On Feb 13, 2019, at 9:07 PM, Joe Touch <touch at strayalpha.com> wrote:
> 
> 
> 
>> On Feb 13, 2019, at 6:12 PM, Jack Haverty <jack at 3kitty.org <mailto:jack at 3kitty.org>> wrote:
>> 
>> …
>> 
>> E.G., the "Multi-homed Host" problem - namely how do you deal with a
>> user computer attached to more than one network.
> 
> See below. Unsurprisingly, it involves a router inside the end “host”.
> 
>>   Does it have two IP
>> addresses? 
> 
> Yes, and more for the internal virtual router.

To add a bit: it takes at least 3.
	1 as the “immutable” address, the unchanging endpoint of the host
	1 each for the IP addresses on each of the subnets

The basic approach is to run the host as if it runs on an overlay that uses the two other addresses, i.e., to treat the multihoming as a “link” change, rather than a network one.

> 
>> Can it effectively use both network ports at the same time? 
> 
> Yes, with “policy routing”.
> 
>> Can it be constrained to not act as a gateway?
> 
> Yes.
> 
>> ...
>> 
>> I haven't been involved for a while, but I wonder if those outstanding
>> problems have been solved, perhaps in IPV6.
> 
> We experienced this problem in the mid 90s when trying to deploy a somewhat unreliable prototype “gigabit LAN” for operational use. We wanted division-wide participation, but not to interfere with use if (when) the links failed. That included avoiding renumbering impact on long-lived TCP connections (notably telnet logins), NTP (which we couldn’t restart on new addresses without affecting running programs using disk-based files), etc.
> 
> Our solution is documented here, and became part of the basis of our understanding of the nuances of overlay networks in the X-Bone project:
> 
> Touch, J; Faber, T: Dynamic Host Routing for Production Use of Developmental Networks <>. In: ICNP, pp. 285-292, IEEE, 1997.
> 
> Joe
> 
> 

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