[neelc]

When I had CenturyLink, I replaced the ONT via a JTAG cable on the new ONT. The stock CL ONT (Calix 716GE-I R2) had a 16384 connection limit, which prevented me from running high-bandwidth Tor relays. The new ONT (Calix 803G) did not.

Calix for some reason makes it easy to clone some models.

I have a post on this: https://www.neelc.org/posts/clone-calix-ont/

Now I'm in NYC with Verizon Fios where I don't need a cloned ONT. Woo! The Verizon ONT is big and has a huge power brick, presumably because of RFoG alongside GPON.

[ImSorryButWho]

That's very cool, but just to point out: that's not JTAG, it's serial (UART).

JTAG is a much lower level protocol, typically used for hardware or low-level software debugging. Serial/UART gives you a command-line interface to the software that's running.

Using a JTAG interface is a lot more complicated. If you're interested in playing with it, check out OpenOCD.

[muppetman]

How is the ONT, a Layer2/Ethernet device, involved in L3 sessions? Was it also the default gateway/router all rolled up into one?

[neelc]

There is a mis-feature on the ONT called "Broadcom Packet Flow Cache". It apparently speeds up TCP sessions but at the expense of allowing a large amount of then.

Lumen fortunately moved off these ONTs. However, the new Smart NIDs have their fair share of issues from what I heard. I moved out of Lumen territory so have no experience with them.

[bauruine]

Consumer routers are all extremely limited when it comes to many connections. Even an Ubiquiti UDM Pro only allows 65536 by default.