Proposal for Temporary Special Class A Space Guidelines
Wilfried Woeber, UniVie/ACOnet woeber at cc.univie.ac.at
Wed Mar 5 10:28:18 CET 1997
Hi Mirjam!
>Subj: Proposal for Temporary Special Class A Space Guidelines
Good stuff!
Just a couple of minor (general) comments, a few proposals for
clarification in the context of the proposed text, as well as a couple
of questions.
General:
. I'm slightly unhappy with the frequent use of the terms "class A" and
"class C". I think we are trying for a while now to sort of phase-out
the usage of these terms. So I'd prefer to
- clearly qualify the usage of these terms as obsolete, or "old
classful terminology",
- wherever possible, please replace "class x" with the appropriate
address range. I think this would make the paper more obvious
anyway.
. While in general there is a one-to-one correspondance of Local-IR and
ISP (routing-wise), I think we could be a bit more careful to refer
to a Local-IR when we talk about assignments, and to refer to the
routing or operations group of an ISP when talking about
routing/operations.
Apologies, if I'm doing nit-picking again :-)
Wilfried.
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Temporary Special Class A Space Guidelines
Kuehne, Karrenberg
D R A F T
____________________________________________________
Temporary Special Guidelines for
Allocation and Assignment
of address space out of class A ranges.
Mirjam Kuehne
Daniel Karrenberg
Background
Before the introduction of classless inter-domain
routing CIDR [RFC1519] the unicast IP address space
was divided into three ranges called A, B and C each
assotiated with a routing prefix length of 8, 16 and
24 bits respectively. In this context IP addresses
are often called class A, B or C addresses depending
on the range. With CIDR the prefix length informa-
tion is carried in the routing protocols and it is
technically insignificant which particular range an
address belongs to.
Whenever classful routing protocols or obsolete
*** proposal ^^^^^^^^
As long as ...
TCP/IP host implementations are being used the class
*** ^^^^^
"class" (as implied by the particular range)
of the address can become significant because either
it determines prefix length in routing or other
assumptions are being made from the class of the
address. Classful software can be configured to
work properly by using subnetting [RFC950] or basing
configurations on the prefix length implied by the
address class.
The Internet registires have been assigning
***typo ^^^
***proposal addresses out of the class C range for the last cou-
^^^
<insert values here, please>
ple of years because this was believed to cause the
least problems with obsolete classful software on
the perimeter of the Internet.
However there is only a limited amount of unallo-
cated class C address space available. More than 50%
of the class C address space is allocated and some
parts of the remaining ranges are reserved by IANA.
Currently the largest amount of unallocated addresses
***proposal is of class A. Therefore regional Internet registries
^^^
<insert values here, please>
will at some point have to use allocations from class A
space.
In April 1995 an experiment started to find out
if classless use of the former class A addresses
(1.0.0.0 - 126.255.255.255) would create any signifi-
cant problems wrt routing. The aim of this experiment
____________________________________________________
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Temporary Special Class A Space Guidelines
Kuehne, Karrenberg
D R A F T
____________________________________________________
is described in RFC1797.
The experiment ran for 6 month and was considered
***typo a success.The results of are described in RFC1879
^^^^^^
including possible problems and solutions.
RIPE Community Initiative
To promote the use of classless addressing the RIPE
NCC has taken initiative to give local IRs in its
service region a choice of allocations either from
class C or class A space.
At the 26th RIPE meeting held in Amsterdam in Jan-
uary 1997 the RIPE community welcomed this initia-
tive and expressed their interest in assigning this
type of addresses to their customers. There was
consensus that in order to encourage usage of class
A address space, allocation and assignment guide-
lines for this space should be temporarily relaxed
if IANA and the other regional IRs agree to this.
The RIPE NCC was asked to make a proposal.
The following sections will describe the special
allocation procedures the RIPE NCC proposes.
Special Allocation Rules
From April 1997 until December 1997 special guide-
lines will apply to the allocation and assignment of
class A address space. These guidelines are addi-
tions to the normal procedures [ripe-140].
***sugg. ^^^^^^
regular? basic?
During this time every orgnisation established as a
***typo ^^^^
***proposal
<remove the phrase "organisation established as a",
unless it refers to something special which I don't
understand?>
LIR in the service reigion of he RIPE NCC may
***typo ^^^^
request an additional allocation of class A address
space.
This means for a limited amount of time each LIR can
***sugg. ^^^^
any ?
hold two allocations of the same size: one from
class C address space (currently 195.0.0.0/8) and
one from class A (to be allocated by IANA).
* In order to limit the adverse effect of these spe-
* cial allocations on routing table growth, global
* routing annnouncements for this address space should
* be kept at an absolute minimum. Ideally each allo-
* cation will be announced via just one prefix. Addi-
* tional prefixes should only be announced globally if
* this is technically necessary.
***question what is the special case for assignments out of the
traditional class A space, as compared to any other
"regular" assignment by way of the regional and local
regsitries?
Once a LIR has obtained an allocation from class A
space in addition to an already existing allocation
*** sugg. ^^^^^^^
<remove>
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Temporary Special Class A Space Guidelines
Kuehne, Karrenberg
D R A F T
____________________________________________________
from class C space the following rules apply:
1. If the address space from the class A alloca-
***sugg. ^^^
a
tion is entireley assigned, another class A
allocation can be requested.
2. If the address space from the class C alloca-
***sugg. ^^^
a
tion is entirely assigned, another class A or
class C allocation can be requested.
This means that a LIR can have two class A alloca-
tions or one allocation of each class but never two
class C allocations.
After the expiration of the special period the usual
allocation policies apply, i.e. every LIR can only
hold one free alocation of a maximum of a /16 at a
***quest., typo ^^^^
<what is a "free" allocation?>
time. This means that first all allocations the LIR
has at this point in time must be finished before
additional address space can be allocated.
* If the LIR has at this point decided that it will
* not continue assigning from class A address space it
* has the possibility to return the class A alloca-
* tion. It can then request an additional class C
* allocation once the previously allocated class C
* addresses are assigned entirely.
*
***question wrt to routing table size, is the LIR expected to
return the whole block, including the assigned
componentes, or just the subset which has not yet been
assigned?
I'd propose to reclaim the whole block.
Special Assignment Guidelines
In order to motivate not only LIRs to use class A
***sugg. ^^^^
<I think this is targetting ISPs (routing-wise) and
end-users. Strictly speaking, for the LIR it's just
numbers and the LIR shouldn't care :-).>
address space but also end-users to use class A
address space in their networks special assignment
policies apply until the end of the special period.
1. A temporary assignment from class A space in
addition to an already existing assignment from
***proposal ^^^^
class C address space can be made without
^^^^^^^^^^^^^^^^^^^^^
<remove that phrase, *unless* you explicitely want to
restrict that simplified approach to applicants that
do not hold (A or) B space. I think it would be a
good idea *not* exclude that scenario!>
detailed documentation so that the end-user can
experiment with these addresses.
2. This additional assignment can have up to the
same size of the total previously assigned
address space but not more than a /19.
____________________________________________________
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Temporary Special Class A Space Guidelines
Kuehne, Karrenberg
D R A F T
____________________________________________________
* 3. The class A address space must be returned by
* the end-user to the appropriate Internet reg-
* istry 6 months after the assignment or the
* usage of the addresses must be documented prop-
* erly according to normal assignment rules
* [ripe-141].
*
***proposal <
- duration of temporary assignement can be agreed
with the end-user and/or specified by the LIR
- validity expires at the end of the special period
- if the LIR decides to continue to assign addresses
from class A space allocation, then assignment has
to be converted to a regular assignment.
-----> for the else-clause, please see previous comment!
- conversion to a regular assignment involves
submitting documentation according to
ripe-whatever, and adjusting the size of the
assignment if necessary.
>
Note: As per these rules address space assign-
ments can be justified by returning an equiva-
lent ammount of addresses as well as by docu-
menting new use.
4. The LIR is obliged to clearly inform the
address space user about the special rules that
apply to the additional assignment before it is
made. LIRs are encouraged to advise users to
plan ahead.
*** quest. ^^^^^^^^^^
<what?>
5. All assignments no matter from wich allocation
must be registerd in the RIPE database.
Conclusion
In order to promote classless addressing and to
address the shortage of class C address space, the
RIPE NCC proposes to give all LIRs in its service
region the chance to prepare for the final transi-
tion to classless addressing and the use of class A
address space.
This document proposes to create special guidelines
for addresses from class A space until the end of
* 1997. After this period it is expected that most
* registries are prepared to assign class A address space
* to their customers as as well as to their own networks.
*
***comment: This sort of vaguely contradicts the (implied) freedom,
as outlined by this paper, to decline future allocations
from former class A space and to stick with the class C
range?
____________________________________________________
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