Re: Why do we need to go with 128 bits address space ?

Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp> Wed, 21 August 2019 20:03 UTC

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Subject: Re: Why do we need to go with 128 bits address space ?
To: Robert Raszuk <robert@raszuk.net>
Cc: "ietf@ietf.org" <ietf@ietf.org>, "irtf-discuss@irtf.org" <irtf-discuss@irtf.org>, "6man@ietf.org" <6man@ietf.org>
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From: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
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Date: Thu, 22 Aug 2019 04:56:15 +0900
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Robert Raszuk wrote:

> *"Instead, APIs and applications must be modified to detect and react
> against the loss of connection."*
> 
> Well it is clear that you are making an implicit assumption that quality of
> the available paths is equal and all you need to care about is end to end
> connectivity/reachability.

No, as is written in draft-ohta-e2e-multihoming-03.txt:

    Once a full routing table is available on all the end systems, it is
    easy for the end systems try all the destination addresses, from the
    most and to the least favorable ones, based on the routing metric.

    Note that end to end multihoming works with the separation between
    inter domain BGP and intra domain routing protocols, if BGP routers,
    based on domain policy, assign external routes preference values
    (metric) of intra domain routing protocols.

    One may still be allowed, though discouraged, to have local
    configuration with dumb end systems and an intelligent proxy. But,
    such configuration should be implemented with a protocol for purely
    local use without damaging the global protocol.

IGP metric is used as route preference, though, some workaround
of proxy (last paragraph) or having partial routing table on
near ISPs (not mentioned in the draft) may be necessary, until
global routing table becomes small enough to be able to be
held by ordinary hosts.

Note that at the time the draft was written, IPv6 global routing
table was small, which means, at that time, IPv6 worth deploying
despite all the flaws in it.

					Masataka Ohta