nanog at nanog at
Mon Feb 22 14:44:52 UTC 2021

While I don't doubt the accuracy of Lee's presentation at the time, at least two base factors have changed since then:

- Greater deployment of IPv6 content (necessitating less CGN capacity per user)
- Increased price of Legacy IP space on the secondary market (changing the formula) -- strictly speaking, this presentation was still in "primary market" era for LACNIC/ARIN/AFRINIC

IPv6 migration is not generally aided by CGNAT, but CGNAT deployment is generally aided by IPv6 deployment; to reiterate the earlier point, any ISPs deploying CGNAT without first deploying IPv6 are burning cash.

- Jima

From: NANOG On Behalf Of Owen DeLong
Sent: Sunday, February 21, 2021 16:59
To: Steve Saner
Cc: nanog at
Subject: Re: CGNAT

On Feb 18, 2021, at 8:38 AM, Steve Saner wrote:

> We are starting to look at CGNAT solutions. The primary motivation at the moment is to extend current IPv4 resources, but IPv6 migration is also a factor.

IPv6 Migration is generally not aided by CGNAT.

In general, the economics today still work out to make purchasing or leasing addresses more favorable than CGNAT.

It’s a bit dated by now, but still very relevant, see Lee Howard’s excellent research presented at the 2012 Rocky
mountain v6 task force meeting:


We've been in touch with A10. Just wondering if there are some alternative vendors that anyone would recommend. We'd probably be looking at a solution to support 5k to 15k customers and bandwidth up to around 30-40 gig as a starting point. A solution that is as transparent to user experience as possible is a priority.


Steve Saner
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