Ascend Archive
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Re: (ASCEND) was... static IP for NAT? is... still not clear

> I understand that the ISP can make their side randomly assign the same IP
> every time.  But what about if I (the customer) wants to take the fixed
> addresses assigned to me, and build in NAT support using one for the Pipeline
> WAN side interface?

I am not sure I understand the question, perhaps you could supply an example
with sample IP addresses?

If you have fixed, assigned [public] addresses for all your hosts, then why
do you want or need NAT enabled in the Pipeline?

If you only have fixed, not assigned [private] addresses on your LAN and
you have a single address from your ISP, then this is just normal single-
address NAT.  The point is that it does not matter whether the single
public address assigned to the Pipeline is static or dynamic, the address
is obtained during the PPP IPCP negotiations that are performed while
establishing any PPP, MP, or MPP connection.

If you only have fixed, not assigned [private] addresses on your LAN and
you have more than one address from your ISP, then you can optionally
use multiple-address NAT (it requires your ISP to use DHCP).

To quote the documentation:

  Multiple-address NAT can be performed when translating addresses for more
  than one host on the local network. To do this, the Pipeline borrows an
  official IP address for each host from a Dynamic Host Configuration Protocol
  (DHCP) server on the remote network. 

> Where do I put this address in the configuration tables?

What address?  Do you mean the fixed, assigned [public] IP address your
ISP has given to your Pipline?  If so, then the answer is - it doesn't
get put anywhere in the configuration.  Your Pipeline will obtain the
[fixed] address during the PPP negotiations from the ISP's equipment.
As far as the Pipeline is concerned, it does not know whether you have
a fixed address or a dynamic address from your ISP - it just uses whatever
is assigned to it by its peer during the IPCP negotations.

All of the above assumes you are using PPP (or MP or MPP).  If you are using
Frame Relay, since there are no IPCP negotations, there is a specific field
to place the single fixed [public] address of the Pipeline ("FR address").
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