On 1/31/12 1:38 PM, Brian E Carpenter wrote:
IMHO the text should make it
clear that this is the wrong way to use it and give the reasons
why - basically the same information as in the new text, but stated
exactly the other way round. For example
Shared Address Space is IPv4 address space designated for Service
Provider use with the purpose of facilitating CGN deployment.
Shared Address Space is not intended to be used as additional [RFC1918]
space, because either or both of the following issues might arise:
o Shared Address Space could also be used on the Service Provider side
of the CPE, with overlapping subnet or host addresses.
o Some CPE routers behave incorrectly when using the same address block
on
both the internal and external interfaces.
Ah. I think we're in pretty good agreement. The -14 text uses the words
"may be used as [RFC1918] private address space", and I agree with you
that we don't want to use those words. We need to say that though it is
similar to 1918 space, it has limitations. So I wouldn't object to the
above text , but I think we do have to give some indication of the flip
side. I want something that says that Shared Address Space can be used
for other Service-Provider-type uses and are not limited to CGNs. They
can be used on any network equipment willing to do address translation
across interfaces which both use the Shared Address Space, just as CGNs
do. That is, clarify throughout that this *isn't* just like 1918 space
(it has limitations and can only be used in particular circumstances),
but do describe what the conditions are under which it can be used.
In your above, I would even strengthen "is not intended to be used as
additional [RFC1918] space" to "can not be use as [RFC1918] private
address space", and then maybe add something about where it can be used.
In the intro, I would change the second paragraph (and it's sub-bullets) to:
Shared Address Space is similar to [RFC1918] private address space in
that it is not global routeable address space and can be used by
multiple pieces of equipment. However, Shared Address Space has
limitations in its use that the current [RFC1918] private address
space does not have. In particular, Shared Address Space can only be
used on routing equipment that is able to do address translation
across router interfaces when the addresses are identical on two
different interfaces.
Or something to that effect. Does that still capture that Shared Address
Space is similar to 1918 space, it can be used for purposes other than
CGN, but it can't be used everywhere 1918 addresses are used?
pr
--
Pete Resnick<http://www.qualcomm.com/~presnick/>
Qualcomm Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102
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