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Re: ISP and NAT (question and some thoughts)

  • From:
  • Date: Mon Oct 18 14:18:03 1999

oups... just thought of an important issue:

I guess the clients would care about the address remarking;
the DNS process is a good example...


just a thought...

why not expand the IPv4 address field using the 'Fragment offset' and
'Identification' fields?
Use those fields to mark packets at the edge with the destination AS number, for
Customer equipment could use private address space and not bother with the edge
remarking process.
(I know that the fragmentation function would be lost due to this 'extension'.)
(I am also aware of transitioning problems related to what I am proposing; the
routers in the network cannot be upgrade all at once...)



"Alex P. Rudnev" <[email protected]> on 10/18/99 12:46:50 PM

To:   [email protected]
cc:    (bcc: Jeanlou Dupont/RMQ/RELTECCORP)

Subject:  ISP and NAT (question and some thoughts)

Today we see the classical schema ISP/customer; this means
- the customer have his own address space, requested by him (directly or
- due to the lack of public addresses, the customers are forced to use
NAT; just NAT provide some extra security
- ISP do not provide NAT themself; NAT configuration is not easy task and
cause a lot of headache for the customers (just as a lot of money they pay
to the network admins).

First question - is this picture right or it is wrong?

The second question. What prevent the _future ISP_ from some another
schema, when:
- the customer always use the private address space, for example,;
- the provider bother about address translation, just as about name
translation (DNS re-writing), just as about the address allocation (not
the customer but the provider - if existing address space is not enough);
- the providers's software learn about _open, or public_ services which
must be translated statically, from the customer using (for example) DNS.

Don't answer _it's too slow_.

This is my attempt to predict where we are going this days. Today the
_know-how_ the customer should know is too huge - if (if I am the admin of
the company, not ISP!) I open electronic
market or want to get Internet for the companies employees, I must
allocate space (why? What for? It's not my concern, if we think a little),
I must prove I need this addresses (why? This is my business how much
addresses I need internally; and let's software decide how much addresses
I need externally), and I should configure firewalls and NAT's. We used to
think about it as about the normal admin's knowledge; but why we are sure
it's normal. If you got a car (in USA, not in the Russia), you don't
bother about the oil stations or about the roads - you just use it.

This is not really a dump question. If it is possible to build such
Internet service when every customer should be free to use any address
space in the hidden way, and ISP (not the customer) bother about the
global address and name translation, we should have just this hierarchical
address schema IPv6 offer to us. On the other hand, it means a great
increase in the NAT engine.

Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N
13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)