Smaller than a /24 for BGP?

Donald Eastlake d3e3e3 at
Sat Jan 28 18:14:43 UTC 2023

Use Multipath TCP

 Donald E. Eastlake 3rd
 2386 Panoramic Circle, Apopka, FL 32703 USA
 d3e3e3 at

On Sat, Jan 28, 2023 at 10:07 AM William Herrin <bill at> wrote:

> On Fri, Jan 27, 2023 at 9:49 PM Masataka Ohta
> <mohta at> wrote:
> > That multihomed sites are relying on the entire Internet
> > for computation of the best ways to reach them is not
> > healthy way of multihoming.
> This was studied in the IRTF RRG about a decade ago. There aren't any
> other workable ways of multihoming compatible with the TCP protocol,
> not even in theory. Every other mechanism imagined failed some basic
> system constraint, usually the requirement that packets have
> administrative permission to cross an intermediate network. So,
> another way of multihoming critically depends on replacing the layer-4
> protocols with something that doesn't intermingle the IP address with
> the connection identifier.
> For clarity: TCP's connection identifier consists of the source and
> destination IP addresses plus the source and destination ports. Those
> four elements, unique when combined, identify exactly one ongoing TCP
> connection. Because of this, the connection must fail if the source or
> destination IP addresses are no longer available to the source or
> destination hosts. From this fact, we get the requirement that the
> entire Internet learn when a particular IP address has changed its
> position within the network.
> Regards,
> Bill Herrin
> --
> For hire.
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