How to use Cisco's NAT

Mon Nov 10 00:02:29 UTC 1997

>Does anyone know where there are some pointers on using the 11.2 NAT stuff
>with Cisco?  Also if it works worth anything?  I've been searching cio for
>some info, but so far no examples...

>Also, does it work with 2501?  Specifically I am working on setting up
>part of my BGP space with very small IP blocks for customers but with a
>NAT on the front end (if it works worth anything) so that I don't have to
>play the "I need more address space" game with customers.  Also the problems
>associated with customers changing IP providers is starting to go up as
>well...

A 2501 can do it but you need the IP+ IOS that lists for $700 more
that the plain $1200 IP license. (You can buy a whole NAT capable router 
elsewhere for that - RAD, Proteon, etc.

Cisco's NAT really wants to 'NAT' everything on some interface
and I was warned NOT to try running non-NATted secondary subnets
on the same ethernet.

Perhaps you could have frame relay subinterfaces for NAT customers
running NAT at a central site.

I have been running NAT at the 16xx/2501 at the customer site. Use a 
/27, /28, or /29 for them, STATIC allocate a few NAT translations
for their servers, and chuck all the rest into pool you run in
OVERLAOD mode for all their random hosts to use.

The 1601's IP license is $600 and IP+ for NAT is $1000 (traditional
direct list vs -PRO pricing via distribution which totals about the
same but gets confusing in the middle). The new 1605 has DUAL etherent,
has 8 rather than 2 meg soldered in, and so still leaves all
of a 16 meg DRAM simm untouched if running -mz images from DRAM.

Curiously, unlike the memory-access challenged 2501, the 16xx family
wins a 35% speed boost running fron DRAM. ONly the 1605
ships with te -mz image, but ANY 16xx can load and decompress
that image into DRAM, and run.

And a 1605's 2nd ethernet would allow NAT and normal nets
at a site.

Also notice Bay's NetGear's new $339 street price ISDN **ROUTER**
(yes a real router to ETHERNET), that ***INCLUDES*** NAT!
A product manager allowed as how a serial port might be
less $s than their BRI version, and this was just the first of
a family. Unlimited NATted hosts, i.e. no 'games' their competition plays.

Buy a cisco 36xx with dual PRIs and let them dial in! if your users don't
pay message units or if you can get flatrated Centrex like
service...

Of course buy your telco PRIs from a friendly ISP turned C-LEC :-)