Proposal for Temporary Special Class A Space Guidelines
Mirjam Kuehne Mirjam.Kuehne at ripe.net
Tue Mar 4 15:26:26 CET 1997
Dear chair people and local registries, dear IANA,
During the Local IR working group at the 26th RIPE Meeting in January
in Amsterdam we learned that many local registries would be interested
and prepared to assign addresses from former class A space.
Because most registries have no experience with class A adddress space
yet the RIPE NCC proposes to introduce new guidelines for a certain
period of time.
The proposal is attached below. Please send all comments, questions
and suggestions you might have until the 17th March 1997 to me
personally. We are planning to publish the proposal as a RIPE document
after this date.
Kind Regards,
Mirjam Kuehne
Manager Registration Services
RIPE NCC
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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
TCP/IP host implementations are being used the class
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
addresses out of the class C range for the last cou-
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
is of class A. Therefore regional Internet registries
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
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is described in RFC1797.
The experiment ran for 6 month and was considered
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].
During this time every orgnisation established as a
LIR in the service reigion of he RIPE NCC may
request an additional allocation of class A address
space.
This means for a limited amount of time each LIR can
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.
Once a LIR has obtained an allocation from class A
space in addition to an already existing allocation
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Temporary Special Class A Space Guidelines
Kuehne, Karrenberg
D R A F T
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from class C space the following rules apply:
1. If the address space from the class A alloca-
tion is entireley assigned, another class A
allocation can be requested.
2. If the address space from the class C alloca-
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
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.
Special Assignment Guidelines
In order to motivate not only LIRs to use class A
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
class C address space can be made without
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
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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].
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.
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.
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