This seems like the best course of action. Allocate 240/6 for private
use as soon as practical and hold the rest of the E Class for private or
public use as seems best later.
From: Daniel Senie [mailto:dts(_at_)senie(_dot_)com]
Sent: Thursday, August 09, 2007 12:06 PM
To: Marshall Eubanks
Subject: Re: I-D ACTION:draft-wilson-class-e-00.txt
If the IETF published an RFC that reassigned 240/4 to private address
space usage today, it would likely be possible for enterprises to use
it within a reasonably short period, perhaps a year or so, depending
on how many vendors they work with, and their ability to assert
Let's look at the reality of software stacks in the present time.
Micorosoft updates desktops and servers weekly or more often, and
people are fearful enough of security matters that they do apply
them. Linux vendors similarly release patches quite often. Router
vendors seem to have new software for one fix or another daily.
If enterprises started working toward a deployment of pieces of
240/4, vendors would make it possible.
A few of us looked at the Class-E issue some years ago, and thought
it was worthwhile at that time to reclassify the space. Everyone
understood it would take some time before the space was widely usable.
If there's to be any use of the space, ever, a scenario that would
get us to usability might be:
- Reclassify Class-E space as usable address space
- Enable a few pieces of 240/4 as private address space use. Let
people start using that.
- Enterprises, if there's interest will push vendors to make changes to
- In a few years, evaluate whether the space is viable for public
assignment by ARIN, et. al.
Even if the initial use of such space is limited to a few platforms
and routers, it may be sufficiently useful to enterprises to use in
private interconnects between companies, an area where significant
difficulties are encountered today due to address re-use.
There will of course be a chorus of responses that if changes are
required anyway, folks should just migrate to IPv6. The
counter-argument I'd make is simple: the changes required in IP
stacks to enable Class-E as valid addressing is minimal, resulting in
little new code, and thus little risk from untested code. Initially
allowing blocks from this space as additional RFC1918-style space
would provide a playground where enterprises, users and vendors could
test their wares, without risk to the public Internet.
For enterprises, the migration to IPv6 will be slow. The protocol
stacks from all of the vendors are largely untested. I don't mean
they haven't run code coverage, had QA teams and even
interoperability testing. I mean there is limited experience with
wide scale networks, high traffic volumes, exposure to denial of
service and probing attacks. There will be vulnerabilites, just as
there is with any code that's relatively new.
As I believed several years ago, reclassifying 240/4 is worthwhile.
Leveraging the need of enterprises for additional, sanctioned,
private IPv4 space for interconnects may result in widescale
implementation. Or it might not. The point is, it would be relatively
simple to find out, and would not be overly distracting to the IETF
or to efforts to migrate to IPv6 .
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