On Feb 3, 2025, at 17:03, Amos Rosenboim via NANOG <nanog@nanog.org> wrote: The requirement for state full traffic flow is given by the customer. Organizations sometimes state that they’ve requirements in specializesd contexts which are in fact counterproductive; in such cases, they can often benefit from education in order to make contextually optimal decisions. The logic behind it is to avoid unnecessary paging procedures for idle mobile devices. ‘Paging procedures’? It protects both signaling resources of the network and also battery life of devices. There are other ways to accomplish this. This was very relevant in the early 2000s, not sure if it’s relevant for today. It was a huge mistake in the late 1990s and early 2000s, as the early GPRS and EDGE wireless broadband networks which were implemented in the same fashion as poorly-designed, state-ridden enterprise networks constantly experienced severe operational problems until they were remediated, one way or another. However it remains a customer requirement. See above. As for clients recovery from flow interruption - from incidents we had in the last few years and observing how fast connection ramp up on the alternate devices it seems that clients are recovering very quickly. Introducing stateful firewalls in front of a population of Internet broadband clients is a Very Bad Idea. DDoS attacks are attacks agains capacity and/or state; and outbound/crossbound attacks can be just as disruptive as inbound attacks. This precise scenario has played out many times, over the years. Networks which were suboptimally designed in this fashion were either completely re-designed in order to be scalable and resilient, removing unnecessary and harmful state; were acquired and their brittle, fragile, non-scalable state-ridden infrastructure was decommissioned; or went out of business. The few holdouts in the present day inevitably experience the problems described above, and then proceed through the same evolution as other network operators with similar architectures. My main concern is that this customer has pretty traditional mind set and never like being the first deployment of any technology. NAT64/DNS64 with 464XLAT or something along these lines isn’t new technology; on the contrary, it’s quite mature, and deployed around the world. It isn’t stateless, but it’s much more scalable than sticking stateful firewalls everywhere, heh. Designing and implementing a broadband access network with this sort of architecture isn’t going to end well. It isn’t beyond the realm of possibility that these ‘requirements’ are largely driven by a supplier of stateful firewalls, or an internal advocate for same.

On Mon, Feb 3, 2025 at 12:15 PM Amos Rosenboim via NANOG <nanog@nanog.org> wrote:

Roland,

Thanks for your comments.

As much as I love to be a network purist who hates state maintenance in the core of the network, the sad reality is that these devices are there and will remain there for the foreseeable future.

Mobile operators need IPv4 address sharing and many of them choose to do it with CGNAT.

Even with IPv6, many of the operators I know of do not allow internet initiated traffic towards their subscribers. Some of their reasons are even surprisingly valid, such as avoiding unnecessary paging in the network.

Regardless of this, my original message as looking to get some deployment feedback on NPTv6 in service provider networks. Any such feedback is appreciated.

I do not think any service providers have deployed NPTv6 at any scale. That’s my feedback. You are building something quite bespoke , not best practice, and should anticipate novel problems.

Cheers,

Amos Sent from my iPhone

On 3 Feb 2025, at 14:41, Dobbins, Roland <Roland.Dobbins@netscout.com> wrote:

 *External sender - pay attention*

On Feb 3, 2025, at 17:03, Amos Rosenboim via NANOG <nanog@nanog.org> wrote:

The requirement for state full traffic flow is given by the customer.

Organizations sometimes state that they’ve requirements in specializesd contexts which are in fact counterproductive; in such cases, they can often benefit from education in order to make contextually optimal decisions.

The logic behind it is to avoid unnecessary paging procedures for idle mobile devices.

‘Paging procedures’?

It protects both signaling resources of the network and also battery life of devices.

There are other ways to accomplish this.

This was very relevant in the early 2000s, not sure if it’s relevant for today.

It was a huge mistake in the late 1990s and early 2000s, as the early GPRS and EDGE wireless broadband networks which were implemented in the same fashion as poorly-designed, state-ridden enterprise networks constantly experienced severe operational problems until they were remediated, one way or another.

However it remains a customer requirement.

See above.

As for clients recovery from flow interruption - from incidents we had in the last few years and observing how fast connection ramp up on the alternate devices it seems that clients are recovering very quickly.

Introducing stateful firewalls in front of a population of Internet broadband clients is a Very Bad Idea. DDoS attacks are attacks agains capacity and/or state; and outbound/crossbound attacks can be just as disruptive as inbound attacks.

This precise scenario has played out many times, over the years. Networks which were suboptimally designed in this fashion were either completely re-designed in order to be scalable and resilient, removing unnecessary and harmful state; were acquired and their brittle, fragile, non-scalable state-ridden infrastructure was decommissioned; or went out of business.

The few holdouts in the present day inevitably experience the problems described above, and then proceed through the same evolution as other network operators with similar architectures.

My main concern is that this customer has pretty traditional mind set and never like being the first deployment of any technology.

NAT64/DNS64 with 464XLAT or something along these lines isn’t new technology; on the contrary, it’s quite mature, and deployed around the world. It isn’t stateless, but it’s much more scalable than sticking stateful firewalls everywhere, heh.

Designing and implementing a broadband access network with this sort of architecture isn’t going to end well. It isn’t beyond the realm of possibility that these ‘requirements’ are largely driven by a supplier of stateful firewalls, or an internal advocate for same.

If you have received this e-mail in error, please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the content of this information is strictly prohibited.

On Feb 4, 2025, at 12:26, Amos Rosenboim <amos@oasis-tech.net> wrote: What other problems do you anticipate ? All the issues mentioned earlier in this thread. There are multiple techniques available to ameliorate the side-effects of aggressive scanning in a network using NAT64/DNS64 with 464XLAT.

I feel like you are conflating two things, stateful firewalls and NPTv6 or any form of NAT, they are often done at the same box together, but they are not inherently linked. I dislike NAT in an IPv6 environment as I've generally not found a use for it not better served by something else, but also IPv6 things are not used to NAT being used, I'd expect much more breakage given that most IPv6 stacks are likely not well tested in the presence of NAT. IPv4 things have learned how to accept ans handle NAT and some of that I'm sure carries over to IPv6, but in IPv6 it's very much an edge case, where it's the norm in IPv4. I do understand the desire for a stateful firewall in the IPv6 context and see them deployed at home/business/enterprise network edge pretty much for every IPv6 enabled network, often with a carve-out for icmp, but otherwise blocking all inbound traffic not matching an existing connection initiated by the device behind the firewall. You may have some reason you can't just employ a stateful firewall without NAT, but if so you haven't said so and seem to have linked them as if they were inseparable, a stateful firewall will block internet initiated traffic, which seems to be the main goal you have, and it will not have the negative side effects of NAT, though you do have the need to force symmetrical routing at the point of the firewall and carry state (though as long as routing symmetry is maintained a user's traffic can freely use multiple firewalls for different traffic, say one for traffic headed towards a content provider cache box and a different one for traffic heading onto the general public internet, which may help with some scaling considerations) On 2/3/2025 3:14 PM, Amos Rosenboim via NANOG wrote:

Roland,

Thanks for your comments.

As much as I love to be a network purist who hates state maintenance in the core of the network, the sad reality is that these devices are there and will remain there for the foreseeable future.

Mobile operators need IPv4 address sharing and many of them choose to do it with CGNAT.

Even with IPv6, many of the operators I know of do not allow internet initiated traffic towards their subscribers. Some of their reasons are even surprisingly valid, such as avoiding unnecessary paging in the network.

Regardless of this, my original message as looking to get some deployment feedback on NPTv6 in service provider networks. Any such feedback is appreciated.

Cheers,

Amos Sent from my iPhone

...

On 3 Feb 2025, at 14:41, Dobbins, Roland <Roland.Dobbins@netscout.com> wrote:

 *External sender - pay attention*

...

On Feb 3, 2025, at 17:03, Amos Rosenboim via NANOG <nanog@nanog.org> wrote:

The requirement for state full traffic flow is given by the customer.

Organizations sometimes state that they’ve requirements in specializesd contexts which are in fact counterproductive; in such cases, they can often benefit from education in order to make contextually optimal decisions.

...

The logic behind it is to avoid unnecessary paging procedures for idle mobile devices.

‘Paging procedures’?

...

It protects both signaling resources of the network and also battery life of devices.

There are other ways to accomplish this.

...

This was very relevant in the early 2000s, not sure if it’s relevant for today.

It was a huge mistake in the late 1990s and early 2000s, as the early GPRS and EDGE wireless broadband networks which were implemented in the same fashion as poorly-designed, state-ridden enterprise networks constantly experienced severe operational problems until they were remediated, one way or another.

...

However it remains a customer requirement.

See above.

...

As for clients recovery from flow interruption - from incidents we had in the last few years and observing how fast connection ramp up on the alternate devices it seems that clients are recovering very quickly.

Introducing stateful firewalls in front of a population of Internet broadband clients is a Very Bad Idea.  DDoS attacks are attacks agains capacity and/or state; and outbound/crossbound attacks can be just as disruptive as inbound attacks.

This precise scenario has played out many times, over the years.  Networks which were suboptimally designed in this fashion were either completely re-designed in order to be scalable and resilient, removing unnecessary and harmful state; were acquired and their brittle, fragile, non-scalable state-ridden infrastructure was decommissioned; or went out of business.

The few holdouts in the present day inevitably experience the problems described above, and then proceed through the same evolution as other network operators with similar architectures.

...

My main concern is that this customer has pretty traditional mind set and never like being the first deployment of any technology.

NAT64/DNS64 with 464XLAT  or something along these lines isn’t new technology; on the contrary, it’s quite mature, and deployed around the world.   It isn’t stateless, but it’s much more scalable than sticking stateful firewalls everywhere, heh.

Designing and implementing a broadband access network with this sort of architecture isn’t going to end well.  It isn’t beyond the realm of possibility that these ‘requirements’ are largely driven by a supplier of stateful firewalls, or an internal advocate for same.

If you have received this e-mail in error, please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the content of this information is strictly prohibited.

On 2/3/25 15:14, Amos Rosenboim via NANOG wrote:

Even with IPv6, many of the operators I know of do not allow internet initiated traffic towards their subscribers.

Address translation is not required for this function. A stateless ACL can do a lot to limit it especially combined with assigning IPv6 addresses that are not easily guessed or otherwise probed (i.e. use all of that entropy in the least significant 64-bits of the address to your advantage). If you must fully inhibit all unsolicited inbound traffic including that which could, upon stateless inspection, be part of a valid flow, a stateful filter at the appropriate point can accomplish this again without address translation. I don't know if any major mobile networks actually do this on IPv6. I can't imagine it's really necessary on IPv6. Of course, address (and port) translation is a fact of life on consumer access networks for IPv4, these days. There are ways to make much of the stateful part live in places where failure will result in limited damage, and I'm fond of using them where possible. I really don't see a compelling argument for NPTv6 based on what you've described, and all the usual arguments against it still apply.

avoiding unnecessary paging in the network.

While a laudable goal, is this really THAT big of a deal these days? I'd wager the legitimate non-interactive traffic on a typical consumer mobile device (social media, instant messaging services, etc.) probably causes plenty of "paging" anyway and likely quite a bit more than you'd get from unsolicited traffic on a high-entropy IPv6 address with absolutely zero filtering. I was of the impression that modern LTE/5G-NR networks had lots of mitigations for the handset-side power implications of this, too. -- Brandon Martin