Re: [homenet] dst/src routing drafts (for IETF-91 rtgwg)

Jim Gettys <> Wed, 29 October 2014 15:13 UTC

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Date: Wed, 29 Oct 2014 11:13:37 -0400
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From: Jim Gettys <>
To: Ray Hunter <>
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Cc: Ole Troan <>, "" <>, "Fred Baker \(fred\)" <>, "" <>, Mikael Abrahamsson <>, David Lamparter <>
Subject: Re: [homenet] dst/src routing drafts (for IETF-91 rtgwg)
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On Wed, Oct 29, 2014 at 8:05 AM, Ray Hunter <> wrote:

> Fred Baker (fred) wrote:
>> On Oct 28, 2014, at 11:28 PM, David Lamparter<>  wrote:
>>  What I'm personally wondering most in this regard is: to what extent
>>> will larger networks deploy multiple prefixes to the hosts?
>> Well, define “larger”. Any network that gets a PI prefix is unlikely to
>> deploy multiple prefixes. The question is at what size network is makes
>> sense to obtain an AS number and a PI prefix, and use BGP to talk with
>> one’s upstream.
> I don't agree with this statement for the following reasons.
> Availability: There are many enterprises that have very numerous far-flung
> sales-office type locations which do not host any critical data or
> applications, but which could benefit from higher availability than that
> provided by a single ISP provider (some of which are currently served by a
> specialised box offering a Very Small Office Service running dual IPSec
> tunnels to a central site, which then performs the break out to the
> corporate intranet/Internet)

​And we are now deploying home networks that are being used for home health
medical monitoring; having full fail-over to another ISP is in the process
of becoming a "life" issue​.

> Latency: There are many sites which could benefit from local Internet
> breakout to regional cloud services, where you don't want to suffer the
> latency associated with a back haul from an office in Australia to a
> regional hub in Hong Kong, or even East coast US to West coast US and back.
> You'd still also want some back up via the central breakout if the local
> breakout failed.
> Cost: There are cost savings to be made in many countries where private
> network services are still many orders of magnitude more expensive than
> plain old Internet. So Internet offload for non-mission-critical traffic
> can be very attractive. If you could achieve this via direct host-server
> connections using address selection rules or multipath TCP; rather than via
> PBR, GRE tunnels + NAT, that would be a lot simpler.


>    Wherever that boundary is, below that networks will use PA prefixes.
>> The question then becomes: will they multi home?
>> And I think the answer today is that we don’t know the answer.
> This I agree with.

​Ditto.  Though I have a personal opinion that they will... How else can
you be able to test that things are actually going to "work" in the face of
loss of one ISP? Anything not being tested on an ongoing basis is unlikely
to work in the case of failure.  If availability really matters, you care...



> --
> Regards,
> RayH
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