| Quote from: danludlow |
| Thanks for your reply AndyH. So you're saying that DLM does not worry about CRC errors at all? I notice that the SNR Down is 10.1, whilst Up is 6.0, when my connection was reset at the cabinet about 3 weeks ago, both were at 6.0 and speeds down were higher, I assume that's DLM? Why does it affect Down, but not up? I can only think its because there are CRC's down (14K in 6 days) but there are "Never" any up (I have not seen an up CRC in months). |
DLM looks are three things - ES/SES and retrains.
| Quote from: danludlow |
| If the ASUS modem fails OR testing, why is it sold as a solution and why do reviews highlight it as a modem with higher performance worth consideration? it is far from cheap. Also, if it's a software issue and it doesn't communicate with BTO equipment, why haven't ASUS already addressed this? Furthermore, with BTO and presumably PlusNet ending supply of "free" modem and router, why have cabinets that don't "gel" with other equipment? |
The problem is more that router/modem manufacturers are producing their devices for global markets - but each country has different network setups. Compared to ADSL2/2+, VDSL2 uses higher frequencies and is a lot more sensitive.
The process with Openreach is that an ISP can submit a modem for conformance testing. It's a lengthy process and it's my understanding that most manufacturers have to tweak and update their firmware to make the router/modems pass all the tests.
I can tell you immediately that there are certain features that end users can control on Asus DSL-x modem/routers which would cause a fail under Openreach's conformity testing. In some countries, this might be useful features but in the UK they can cause issues to other lines on the same DSLAM.
Asus routers aren't cheap, but they are good quality. I think the problem is more the chipset they use for their modems (Trendchip) are not as good as the likes as Broadcom or Lantiq.
| Quote from: danludlow |
| I'm no expert by any means, but DLM seems set to restrict quickly, return to normal ultra slowly. Far too one-sided in my ignorant opinion, if it can react quickly (and it does) what is the harm in attempting to return speeds bit by bit starting 24 hours after the restriction? To wait a week before attempting (as seems to be the case, judging by posts here and on other sites, "speed should hopefully return after about a week" is not an uncommon response). |
Most people blame DLM - but all it is doing is reacting to the information that is sent to it on a daily basis.
Lines are rate adaptive, so they will go as fast as they can to meet the target SNr of 6dB. For the first 48 hours after a new line is installed, it's on an open profile (i.e. DLM is doing nothing) but not every line will sync at 80/20Mbps.
DLM is only restricting a sync speed if someone has their line banded and it is synced at the upper end of the banded profile. This doesn't happen too often though.
In terms of the reactiveness of DLM to make positive changes, it's been designed to act on the side of caution - perhaps too much caution. It does prefer stability over speed, as this is what most end users want. The introduction of retransmission (aside from the ECI issues...) has further reduced errors and given most people a speed increase.
