dslreports logo
 
    All Forums Hot Topics Gallery
spc
Search similar:


uniqs
1665
danboghiu
join:2007-03-17
North York, ON

danboghiu

Member

[Other] TP-Link TD-8840T ADSL2+ modem not achieving 24Mbps8207;

Hi folks,

I currently use a TP-Link TD-8840T modem with a DSL line configured to deliver speeds 24Mbps down / 1.4 Mbps up, however the modem only achieves a maximum speed of ~13 Mbps down / 0.85 Mbps up.

I already contacted the ISP (FibreStream) to troubleshoot the problem and here is the outcome of our investigation:
- the DSL line is correctly set up, as I am able to get 21 Mbps down / 1.1 Mbps up when using the ISP modem (ComTrend CT-5361T)
- resetting the TP-Link modem to factory settings and re-configuring it did not help
- changing the ADSL mode from "Auto Sync-up" to "ADSL2+" did not make a difference
- changing the annex mode did not make any difference

I attached:
- the recommended parameters provided by the ISP, along with a sample configuration for their modem (ComTrend CT-5361T)
- the output of "wan adsl diag" from the TP-Link TD-8840T modem

Clearly the TP-Link modem does not achieve the advertised speed of 24Mbps - it currently syncs with the ISP at a data rate of only 15334 kbps.

Need your help to figure out what what changes I need to make to get the TP-Link up to the wire speed......

Thanks,
Dan
HELLFIRE
MVM
join:2009-11-25

HELLFIRE

MVM

Is this output from the TPLINK or the ComTrend?

wan adsl l n =>
relative capacity occupation: 100%
noise margin downstream: 22.7 db
output power upstream: 11.3 dbm
attenuation downstream: 1.3 db
 

PMD Parameters:
---------------
LATNus      = 32 dB
SATNus      = 29 dB
SNRMus      = 91 dB
ATTNDRus    = 1018 kbps
ACTATPus    = 123 dBm
TRELLISus   = 1
Reserved1   = 0(Should be 0)
 

wan dmt2 show rparams =>
 
**********************
R-PARAMS
**********************
PMD Parameters:
---------------
LATNds      = 13 dB
SATNds      = 0 dB
SNRMds      = 200 dB
ATTNDRds    = 25928 kbps
ACTATPds    = 136 dBm
TRELLISds   = 1
Reserved1       = 0(Should be 0)
 

Don't know about the output above, but I'd DEFINATELY have that reviewed by the ISP, especially about
the noise margins and the "relative capacity occupation." According to this DSLReports FAQ item

Percentage of your overall available bandwidth used to obtain your service ATM rate. For example; if your max line synch rate was 5888Kbps and you were provisioned on a 1472Kbps service you would be using 25% capacity. 1472/5888=25% capacity. The lower the relative capacity the better, but you can still get maximum speeds (although a less stable connection) even with a very high relative capacity. In other words you could be synching at 1472Kbps with 98% relative capacity and achieve maximum speeds, but you may experience more disconnects.

wan hwsar disp =>
 
[ SAR Counters ]
inPkts         = 0x00002080, inDiscards     = 0x00000000
inF4Pkts       = 0x00000000, inF5Pkts       = 0x00000000
inDMATaskEnd   = 0x00000000, inBufErr       = 0x00000000
inCrcErr       = 0x00000000
inBufOverflow  = 0x00000000, inBufMaxLenErr = 0x00000000
inBufLenErr    = 0x00000000, inBufDescrOV   = 0x00000000
outPkts        = 0x0000236e, outDiscards    = 0x0000003c
outF4Pkts      = 0x00000000, outF5Pkts      = 0x00000000
softRstCnt     = 0x00000000
inCrc10Err     = 0x00000000
inMngBufOV     = 0x00000000, inCcBufOV      = 0x00000000
inMngBufDescrOV= 0x00000000, inCcBufDescrOV = 0x00000000
inMpoaErr      = 0x00000000, inVlanHit      = 0x00000000
inCcUDoneErr   = 0x00000000, inCcUBDURErr   = 0x00000000
outAckDiscards = 0x00000000
 

This stuff I can make heads and tails of... about the only field of concern is the outDiscards which has hex 3c / dec 60 packets.

A couple questions

- is the TP-Link TD-8840T giving your computers a 192.168.x.x address?

- If so, any possibility of putting the TPLINK into what's called "bridged mode" ?

- how are you testing your speeds exactly? via online speedtest? some other means?

- are you doing this via a wired or wireless connection to the TPLINK? If over 802.11 wireless, ALL BETS ARE OFF! (I cannot stress this enough).

- are both the ComTrend and the TPLINK issued by the ISP? Either case, if the ComTrend works at the advertised speeds,
I'd say stick with it, unless you have a pressing need to go with the TPLINK.

My 00000010bits

Regards