[arin-ppml] Draft Policy 2010-2: /24 End User Minimum Assignment Unit - Correct Title

James Hess mysidia at gmail.com
Fri Jan 29 09:36:16 EST 2010

On Mon, Jan 25, 2010 at 2:32 PM, Jim McBurnett <jim at tgasolutions.com> wrote:
> As a consultant, I have several customers that are multi-homed. Many have the issue of getting
> IP Space from an ISP.  Some ISP's have to be read ARIN policy on the multi-home requirement
> To allow for a /24.. Granted some of these customers cannot truly justify a /24 for that site.
> HOWEVER-- there are concerns for them to do some other redundancy options..

To successfully multihome,  with an AS number  in the real world and
achieve global reachability  /24  is required.  Even under the current
NRPM,   organizations who are going to multi-home, and can provide
solid business justification why multi-homing is required,  should be
able to  justify a  /24  to their ISP or ARIN on that basis.

That is:  a network design that  requires multihoming  to achieve the
required level of fault tolerance,  and reachability during the
failure of an upstream provider     has a technical requirement for a
/24  or shorter prefix.

Since prefixes longer than /24  are usually not propagated by the
major internet backbones.  There you have a solid justification for a

The primary concern from a policy perspective to ARIN and to the ISP
should be to prevent end-users from LYING  and  showing a network
design that includes multi-homing, where in fact they have no real
intention to multihome  for the redundancy they claim they want.

There is a risk the user could  get their /24,  and then   cancel the
service with their other provider.      Or  just  never  get the
second link in place  (if it was just "planned multihoming")   ---
I.E.  the real reason they wanted the /24 was not to multihome, but to
get IPs;   since they got much more than they need,  they'll never be
coming back to ARIN to get denied a  second allocation, e.g. they're
"set for life".

Or when they really have no solid technical basis for say
multi-homing rather  than getting redundant links from   one
well-connected   multi-homed  upstream  ISP.

If  ARIN  starts allocating  /24s,   it may need to find itself having
to make more decisions like that,  or allow more IP addresses to be
allocated than would otherwise.     Currently  ARIN  doesn't allocate
those, so it needn't worry about it,
only the ISP of the user who requests a /24    (currently)  has to be
concerned with    "Does this user _really_  need to multihome for a
good reason?"

And charging them an appropriate price for that /24,  given the
opportunity cost of allocating that  /24,  and the limited remaining
IPv4 space.


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