[arin-ppml] Why not NAT for Dorms (Was: Suggestion: charging for IPv4 space)
farmer at umn.edu
Tue Oct 21 20:43:54 EDT 2008
On 21 Oct 2008 Ted Mittelstaedt wrote:
> For myself I do not understand why all of these academic
> users keep throwing up examples of student dormotories
> that chew up vast blocks of IPv4. Why does ANY student that
> is getting Internet connectivity for free from the college
> expect to get a public IPv4 number?
There are so many reasons, let me educate you on just a few;
1. Technical the definition I use for NAT (Network Address Translation) is a
one to one internal to external address translator. If I need one external
IPv4 addresses for each internal IPv4 address where is the win? I have
more complexity and cost for almost no win, maybe a 10-20% reduction in
number of IPv4 addresses used by eliminating subnet round up.
2. I think you really meant PAT (Port Address Translation) when you said
NAT, so I need to support at least 10,000 users (this is only the Dorms too)
with at least 250Mb of capacity, and at least 200,000 concurrent
connections. So lets say a Cisco ASA 5540 for discussion, $17,000 (list),
need 2 for redundancy, so $34,000 (list), divide by 5 year life, and add
$4,000 a year for Smartnet (list), comes out to about $10,000 a year for a
PAT/NAT. a /18 is with 16K addresses is only $4500 a year. So explain to
me how it is cheeper? Even with a 50% discount from Cisco it is only
breaks even, and I have included any operation expenses yet, other than
3. Putting all 10,000 users behind a single address or even some small
number of addresses just concentrates the effect of DOS attacks, which
happen every day.
4. Putting all the users behind a single address or even some small number
of addresses means I have to track session info to keep the RIAA and
MPAA happy, that's several servers and a bunch of disk not in the number
above. By using real IPs the RIAA and MPAA have to do the real work.
And if you don't think we should have to do this at all then tell congress that
because they are making our federal dollars contingent on it.
But that is a whole other story;
5. Competition - If students move out of the dorms to get real IPs from
Comcast so all there games and other stuff work then we get a bad
reputation. Students actually take into account the wiredness of a school
when selecting where to go now. That's at least as good as of a reason to
consider than if we are party school or not, dude!!
6. Why should Comcast users expect a real IP address from Comcast? It is
really the same questions.
I'll stop here, but I could keep going on and on...
David Farmer Email: farmer at umn.edu
Office of Information Technology
Networking & Telecomunication Services
University of Minnesota Phone: 612-626-0815
2218 University Ave SE Cell: 612-812-9952
Minneapolis, MN 55414-3029 FAX: 612-626-1818
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