| 1 Jun 2025 |
 K900 | E X C E P T | 12:00:01 |
| K900 | The part where this PON thing lies to you | 12:00:11 |
 emily | okay so like | 12:00:18 |
| K900 | And it's not actually 2500base-x | 12:00:22 |
| emily | here's something from the amazon description of a transceiver i was looking at | 12:00:36 |
| emily |
Set to the X position: Ethernet ports only support 1000/2500M autonegotiation.
a:When connected at 1000M: HOST interface is forced into 1000Base-X mode
b:When connected at 2500M speed: HOST interface is forced into 2500Base-X mode
| 12:00:45 |
| emily | I guess this isn't autoneg? | 12:00:49 |
| K900 | And it's really a computer pretending to be a transceiver plugged into fiber plugged into a transceiver plugged into a computer | 12:00:49 |
| emily | it's just the transceiver only advertising one rate? | 12:00:54 |
| K900 | Yes | 12:01:05 |
| K900 | As you should | 12:01:08 |
| emily | okay but hmmm | 12:01:14 |
| K900 | Except my PON thing advertises FIVE | 12:01:16 |
| emily | let's say I'm a manufacturer trying to make the best 10G/5G/2.5G/1000BASE-T transceiver ever | 12:01:31 |
| K900 | Because unlike the lantiq ones that do the arguably as sane as possible thing | 12:01:36 |
| emily | I know that some things will only support up to 2500BASE-X, but some things will only support 10000BASE-X | 12:01:51 |
| emily | and I want to support plugging in 2.5GBASE-T and using it with either of those devices | 12:01:58 |
| K900 | And actually change their SFP identification bits depending on how they're configured | 12:02:08 |
| emily | don't I really wish I could advertise both 2500BASE-X and 10000BASE-X to the thing I'm plugged into? | 12:02:08 |
| emily | and let it pick based on what it supports? | 12:02:14 |
| K900 | This thing just has a singular literal EEPROM | 12:02:21 |
| K900 | Hardwired to the pins | 12:02:31 |
| K900 | So it can't POSSIBLY advertise itself correctly | 12:02:41 |
| K900 | Becuase the EEPROM does not know what the fuck the rest of the thing is doing | 12:02:52 |
| K900 | In reply to @emilazy:matrix.org
don't I really wish I could advertise both 2500BASE-X and 10000BASE-X to the thing I'm plugged into? That's the fun part you don't | 12:03:11 |
| emily | : ( | 12:03:22 |
| K900 | The "right" way is to just do SGMII | 12:03:23 |
| K900 | And UXSGMII | 12:03:27 |
| emily | okay but like | 12:03:32 |
| K900 | Which both have in-band negotiation | 12:03:33 |
