CGN fixed/hashed nat question

Jean-Francois Mezei jfmezei_nanog at
Wed Jan 23 21:31:47 UTC 2013

Question abbout CGN:

Generally speaking for CGN setups, how many end users are NATed to a
single public IP address ?

In terms of traceability, there is a huge difference between loading
200k end users onto 1 public IP and putting say 5 end users per public IP.

In the later case, it becomes possible to assign a good range of ports
to each of the 5 users on that IP address. In the former case, it isn't.

An ISP who nats 5 customers to each public IP address reduces fivefold
the need for pulic IP addresses, which is still a major accomplishement.

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