routing around Sprint's depeering damage

Matthew Petach mpetach at
Sun Nov 2 20:14:20 UTC 2008

On 11/2/08, Matthew Petach <mpetach at> wrote:
> On 11/2/08, Adam Rothschild <asr+nanog at> wrote:
>  > On 2008-11-02-10:14:14, Matthew Kaufman <matthew at> wrote:
>  >  > But seriously, it shouldn't be necessary to have two connections at
>  >
>  >  This is less than clear, and largely dependent on a specific
>  >  organization's [in]ability to function if their internets go down.
>  >  End-site multihoming in some form or fashion is a growing requirement,
>  >  and folk thinking otherwise need to get their heads out of sand.
>  >
>  >  If anything, these recent de-peerings underscore the lack of wisdom in
>  >  end users connecting to (or purchasing CDN services from) members
>  >  of the tier 1 club directly.
> Thank goodness IPv6 cleanly supports end-site multihoming so we
>  won't ever face messy issues like this in the Internet of tomorrow!
>  Oh, wait--could this end up being a damper on IPv6 deployment?
>  "I'd like to move to IPv6, but I can't multihome in IPv6, and I've seen
>  what happens when you don't multihome--so I'll stick with v4, where
>  I at least have the option to multihome to try to avoid being screwed
>  when the net is partitioned like this."
>  Hopefully people recognize that we're rapidly being caught between
>  the twin perils of Scylla and Charybdis here; on the one hand, we
>  don't want to mandate universal connectivity throughout the Internet,
>  we want to allow networks to engage in squabbles like this, and we
>  tell companies "hey, this is the reality of the internet--you want your
>  customers to have more reliable connectivity, you need to multihome"
>  But at the same time, we're telling them "IPv4 is running out, you need
>  to look at moving to IPv6; oh, by the way, in IPv6, you don't get to
>  multihome, you get your addresses from your upstream, and you're
>  stuck with them; you can buy from multiple upstreams, but you'll
>  have to use some type of kludge to switch addresses to make use
>  of the additional paths."
>  With network partitioning becoming more and more an accepted
>  fact of the Internet, if multihoming in IPv6 is not made at least as
>  easy as it is in IPv4, companies who cannot get PI space will not
>  move to IPv6 for any serious production traffic; they have heard us
>  chant the "you must multihome in order to reach the entire Internet,
>  partitions happen on a regular basis, and we refuse to let anyone
>  put regulations in place to prevent them" mantra enough times to
>  realize that the only viable business model for the forseeable
>  future is to use IPv4 addresses in an end-site multihomed fashion.
>  This is the bed we have created for ourselves; why do we spend
>  so much time here wailing and wishing it were otherwise?
>  Matt

And, just to converge one more set of threads together, including
the recent talk at the NANOG in LA; for those of you complaining
about routing table explosion, who are having to take steps to filter
out routes so that your table still fits in the 256K memory slots your
current kit affords, and for those who are panic-stricken over the
thought of having to upgrade all your routers in case we allow
multihoming in IPv6--it is events like this that drive the message
home that multihoming is a requirement even for smaller businesses
in order to stay well connected in the Internet of today; and it is a
result of this drive for ever-smaller entities to be multihomed that
will drive up routing table size, and force networks to upgrade
their routers.

So--don't want to be forced to upgrade your routers?  Perhaps
mandated interconnection arrangements might not seem so
terrible to your management, if it means you can save millions
on capex for router upgrades.

I think it's only a matter of time before we're forced to choose
between shutting up and doing forced technology refreshes
across wide swaths of the internet to support the swelling
routing tables that are the direct result of additional multihoming
due to events like this (which I'm sure will make the router vendors
quite happy), or accepting mandated interconnection and universal
connectivity requirements which will keep the routing table size
down, as people won't have the same pressures forcing them to
multihome, and will let them contemplate moving to IPv6 without
fear of being partitioned (which I'm sure will make the smaller
businesses happier, as well as the network engineers who will
no longer have quite the gun pointed at their head forcing memory
upgrades of all their router kit).

Personally, I'm betting on the latter outcome, as much as I don't
like it.  Governments seem to be unable to resist getting involved
whenever it seems that some fundamental linchpin of their society
is at risk of faltering or failing without intervention.  And unfortunately,
I've not seen anyone offer a solution yet that solves all the issues:
1)  Prevent or address partitioning of the internet due to depeerings
2)  Provide reasonable assurances to end sites of near-universal internet
     access, barring reasonable outages, maintenance periods, etc. without
     the need for all end-sites to multihome to multiple upstream providers
3)  Provide a reasonable migration path to IPv6, either by re-drafting the
     IPv6 addressing guidelines to allow widespread end-site multihoming,
     or by providing assurances that single-homing will not lead to long-term
     widespread network partitionings due to depeerings or other disputes
4)  Limit the potential explosion of routing table entries and forced technology
     refreshes due to the lack of universal connectivity and the
resulting demand
     for multihoming.

I'm sure I'm just nearsighted; but I don't see any other way to solve
the situation other than through regulation.  Can someone else help
enlighten me as to how else we can deal with these converging,
conflating issues forcing us towards a cliff, before we hit the IPv4
exhaustion point, and realize that we've backed ourselves into a
corner and have no choice but to accept regulation--because we
can't upgrade all our networks fast enough to allow everyone to
multihome in IPv6, and we're not willing to self-regulate ourselves
in the IPv6 world to forbid intentional creation of widespread network


(hoping it's just the lack of breakfast making  him paranoid this morning)

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