Kitz Forum

Broadband Related => Broadband Hardware => Topic started by: Barwell1992 on January 25, 2021, 04:19:07 PM

Title: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: Barwell1992 on January 25, 2021, 04:19:07 PM
Hi everyone,

first post, sorry if this is going over old ground but i can't find anything using the search that quite matched my issue.

The background info:

So i've had a Unlocked HG612 purchased from ebay running in bridge mode for a while now previously used with a Asus AC3200 Router however that started to die with random wifi drops and getting quite hot, i do have a fair amount of devices on the network circa 25-30wifi and 3 wired, so anyway decided to order a Amplifi Alien to replace the asus and basically decided to tidy up everything else and see if i can get any more speed out of the system, this coincided with me upping my BT subscription to fibre 2 FTTC.

First thing i noticed a nice upload speed bump effectively doubling my speed to 17.5Mbps however i noticed my download speed was basically the same at around 42Mbps, so jumped onto BT and reported and issue and they did the online line check as i obviously can't do the speed test without their HH plugged in, all said it was fine, then as if by magic my speed jumped up to 52Mbps (still under the speed guarantee) great i thought, but thought i best check the modem....

The Issue:

So today i decide to log into the HG612 and check the line speeds etc, and i noticed my Line rate download speed is showing as 58672 kbit/s and upload showing at 18627 kbit/s and the attainable rate showing as 58212kbit/s download and 18627kbit/s upload, thats on average 6Mbps down and 1Mbps up faster than i'm seeing at the router using the routers built in speed test.

Does anyone have an idea as to why that might be ? I'm using the supplied amplifi cable to connect from modem to router.

Does anyone have a list of ideal modem settings for a BT VDSL2 line?

modem info/settings below. (sorry about photos)

Any help would be appreciated.
Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: burakkucat on January 25, 2021, 05:38:17 PM
Hi everyone,

first post, sorry if this is going over old ground but i can't find anything using the search that quite matched my issue.

Welcome to the kitz forum.  :)

Quote
So today i decide to log into the HG612 and check the line speeds etc, and i noticed my Line rate download speed is showing as 58672 kbit/s and upload showing at 18627 kbit/s and the attainable rate showing as 58212kbit/s download and 18627kbit/s upload, thats on average 6Mbps down and 1Mbps up faster than i'm seeing at the router using the routers built in speed test.

Does anyone have an idea as to why that might be ?

Please do not look at the HG612 GUI for the status of the VDSL2 circuit, it is muddled and does not display the values in the correct fields. For the correct values, either use telnet or ssh to connect to the modem and issue the following commands --

xdslcmd info --stats
xdslcmd info --pbParams
xdslcmd info --vendor
xdslcmd info --vectoring


Quote
Does anyone have a list of ideal modem settings for a BT VDSL2 line?

There's nothing you really need to change. All VDSL2 (ITU-T G.993.2) circuits, using Openreach cabinet DSLAMs, are provisioned the same. The HG612 modem is, essentially, "plug and play".
Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: Barwell1992 on January 25, 2021, 07:07:46 PM
Hi burakkucat thanks for the welcome and info!

i've run the commands you've listed and get what looks like comparable results to the inbuilt down/up stream?

The stats command output for some reason doesn't like been copied and pasted so its a bit of a mess, i've grabbed the top bit of the command as it also exceeds the character count.

Most of this is way over my head i'm afraid.

# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status:   0
Max:    Upstream rate = 18627 Kbps, Downstream rate = 58212 Kbps
Bearer: 0, Upstream rate = 18627 Kbps, Downstream rate = 58672 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
                  VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:           18627 kbps              58212 kbps
Actual Aggregate Tx Power:             7.4 dBm               12.4 dBm
====================================================================================
        VDSL Band Status                U0              U1              U2              U3              U4
D1              D2              D3
  Line Attenuation(dB):  6.2     24.0    35.1     N/A     N/A    12.1    29.2    45.5
Signal Attenuation(dB):  6.2     23.3    34.0     N/A     N/A    16.7    28.9    45.4
                SNR Margin(dB):  5.9     6.0     6.0      N/A     N/A    5.2     5.2     5.2
                 TX Power(dBm): -0.5    -19.9    6.7      N/A     N/A    8.1     7.8     6.9
# xdslcmd info --vendor
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status:   0
Max:    Upstream rate = 18627 Kbps, Downstream rate = 58212 Kbps
Bearer: 0, Upstream rate = 18627 Kbps, Downstream rate = 58672 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
ChipSet Vendor Id:      BDCM:0xa4a1
ChipSet VersionNumber:  0xa4a1
ChipSet SerialNumber:   XDMJ4600189_01
# xdslcmd info --vectoring
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status:   0
Max:    Upstream rate = 18627 Kbps, Downstream rate = 58212 Kbps
Bearer: 0, Upstream rate = 18627 Kbps, Downstream rate = 58672 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Vectoring state: 5
VCE MAC Address: 0:0:0:0:0:0
Total error samples Ethernet pkts sent: 0
Total error samples Ethernet pkts discarded: 0
Total error samples statuses sent: 0
Total error samples statuses discarded: 0
#

Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: burakkucat on January 25, 2021, 09:48:49 PM
i've run the commands you've listed and get what looks like comparable results to the inbuilt down/up stream?

The stats command output for some reason doesn't like been copied and pasted so its a bit of a mess, i've grabbed the top bit of the command as it also exceeds the character count.

Most of this is way over my head i'm afraid.

Let's see if some of our more knowledgable members can spot anything odd in those statistics and can also give you a rundown on what they see.
Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: Barwell1992 on January 26, 2021, 12:14:32 AM
Just to make sure there wasn’t something I was missing with the alien I contacted amplifi’s support, they told me to run a speed test with a laptop connected direct to modem in bridge mode with PPPoE configured on windows and run the test on Speedtest.net, then do the same again on all the lan ports on the Alien. Guess what... there almost indistinguishable.

Top test in the image below is laptop direct to modem, the other 4 are the ports on the alien.

Modem is still reporting 58Mbps down over telnet and GUI  :shrug2:
Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: Alex Atkin UK on January 26, 2021, 02:48:42 AM
I'm confused nobody has mentioned this already, the line rate is the RAW data rate.  Real-world throughput is ALWAYS considerably less than that because of protocol overheads.

Getting 52Mbit out of a 58Mbit sync is pretty much in line with what I'd expect.  Likewise I can upload at around 17Mbit when synced at 20Mbit up.  Its pretty safe to assume you will get at LEAST 10% less than the line rate if you are on fast-path, even less if you are Interleaved.
Title: Re: HG612 paired with Amplifi Alien, speed discrepancy, settings advice.
Post by: Barwell1992 on January 26, 2021, 10:56:43 AM
I'm confused nobody has mentioned this already, the line rate is the RAW data rate.  Real-world throughput is ALWAYS considerably less than that because of protocol overheads.

Getting 52Mbit out of a 58Mbit sync is pretty much in line with what I'd expect.  Likewise I can upload at around 17Mbit when synced at 20Mbit up.  Its pretty safe to assume you will get at LEAST 10% less than the line rate if you are on fast-path, even less if you are Interleaved.

Thanks for the info!