MAP-T (was: Re: V6 still not supported)

Vasilenko Eduard vasilenko.eduard at
Fri Mar 25 14:59:27 UTC 2022

Hi Jared,
Theoretically, MAP is better. But 

1. Nobody has implemented it for the router.
The code for the CGNAT engine gives the same cost/performance.
No promised advantage from potentially stateless protocol.

2.MAP needs much bigger address space (not everybody has) because:
a) powered-off subscribers consume their blocks anyway
b) it is not possible to add "on the fly" additional 64 ports to the particular subscriber that abuse some Apple application (and go to 1k ports consumption) that may drive far above any reasonable limit of ports per subs.
Design should block a big enough number of UDP/TCP ports for every subs (even most silent/conservative).

-----Original Message-----
From: NANOG [ at] On Behalf Of Jared Brown
Sent: Friday, March 25, 2022 4:49 PM
To: nanog at
Subject: MAP-T (was: Re: V6 still not supported)

Most IPv6 transition mechanisms involve some form of (CG)NAT. After watching a NANOG presentation on MAP-T, I have a question regarding this.

Why isn't MAP-T more prevalent, given that it is (almost) stateless on the provider side?

Is it CPE support, the headache of moving state to the CPE, vendor support, or something else?

NANOG 2017
Mapping of Address and Port using Translation MAP T: Deployment at Charter Communications

- Jared

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