ADSL Trouble Shooting & Tweaking

The NDSC provides a level 2 support role in Big Pond Advance ADSL activation and assurance for the AATC and field staff involved. Most of the information on this page has been found by research and much experimentation with the authors home service.

The service is offered in several different speed plans 256/64, 512/128, and 1536/256kbps. The speeds referred to are expressed as RX/TX, ie. the higher speed downstream towards the customer. As part of the installation, a NIC (Network Interface Card) is installed in the PC and Big Pond client software installed. See the ADSL installation guide for more information.

The Big Pond client software uses PPPoE (Point to Point Protocol over Ethernet) protocol to provide dial-up like connectivity. The current client software NTS Enternet 1.3 as supplied on the version 2.1 installation CD. This client is supported on Windows 95/98/ME/NT4/2000 and Mac OS 8.1 and later platforms. Linux is not officially supported by Big Pond however roaring penguin is a excellent PPPoE client that works with Big Pond.

Newer operating systems such as Windows XP and Mac OS X support PPPoE natively. With these OS's there is no need to install a 3rd party PPPoE client such as Enternet.

The standard NTS Enternet client installation has a number of bugs that may cause the following problems.

1. (a) A regular stalling/freezing/pausing of internet browser for up to 30 seconds every 5 minutes.

(b) Inability to surf the internet or check mail for 5-6 minutes after successful authentication and connection.

This is caused by the the network adaptor card being set for a server assigned IP address. So every 5-6 minutes throughput will hang while a broadcast message is sent out looking for a DHCP server. I would recommend that new services are installed with a static IP address assigned to the NIC (Network Interface Card). To fix see below.

Windows 2000: Click Start/Settings/Network and Dial-up Connections. Right click on the "Local Area Connection" icon applicable to the physical network adaptor, usually "Local Area Connection". The name of the adaptor should be displayed in the "Connect using" box, this should be something like SMC EZ xxx Card. If the NTS Enternet PPPoE adapter is shown you have the wrong "Local Area Connection" icon, try the other. Now double click on Internet Protocol (TCP/IP). Change the radio button to "Use the following IP address". Type in 10.0.0.1 as the "IP address" and 255.255.255.0 as the "Subnet mask", leave "Default gateway" blank. Click "OK", then "OK" again.

Windows 95/98/ME: Click Start/Settings/Control Panel, then double click the "Network" icon. Double click on "TCP/IP->SMC EZ xxx Card". Change the radio button to "Specify an IP address". Type in 10.0.0.1 as the "IP address" and 255.255.255.0 as the "Subnet mask". Click "OK", then "OK" again, the computer will now want to restart.

A secondary advantage of this setup is now the ADSL modem can be pinged directly from the customers PC. This may be helpful in diagnosing hardware problems relating to the customers PC.

To ping the modem, bring up a DOS box and type in ping 10.0.0.138. You should get response times 2ms or less at this point if all is well.

To ping the NIC in the PC, bring up a DOS box and type in ping 10.0.0.1. You should get response times 1ms or less at this point if all is well.

2. (a) Inability to load some web sites with browser, these are sites that usually employ SSL (secure sockets layer) and Java.

(b) Random stalling/freezing/pausing when using using browser or checking e-mail/news.

It probably doesn't hurt to check AWS first, make sure the line has low occupancy figures and plenty of noise margin to rule out any line problems. Make sure MTU path discovery and MTU black hole detection is enabled. If not, IP packets may become fragmented by routers along the path. Web pages will fail to load under the PPPoE protocol when this occurs. A maximum MTU size of 1454 is currently recommended, this is the Enternet default, see here for more information on a optimising MTU size.

Windows 2000: Click Start/Settings/Network and Dial-up Connections. Right click on the "Local Area Connection" icon applicable to the NTS Enternet adaptor, usually "Local Area Connection 2". The name of the adaptor should be displayed in the "Connect using" box. Now click on the "Configure" button, then click the "Advanced" tab. Click on "MaxFrameSize", check the value is set to 1454. Click "OK", then "OK" again, restart the computer for the settings to take effect.

Windows 95/98/ME: Click Start/Settings/Control Panel, then double click the "Network" icon. Double click on the "Network Telesystems PPPoE Adapter", then click the "Advanced" tab. Click on "MaxFrameSize", check the value is set to 1454. Click "OK", then "OK" again, restart the computer for the settings to take effect.

RASPPPOE is another PPPoE widely used client unsupported by Big Pond. This client has a MTU size of 1492 by default, refer to the RASPPPOE documentation for information on changing this.

To check MTU size, path discovery and black hole detection settings, visit this page http://www.dslreports.com/tweaks and perform the test. Check the results and note the findings.

We usually can fix this in Windows 98/ME by running the PMTU registry patch file available for download below. Note this is not for Windows NT/2000. After you have run the patch reboot the PC and re-run the test above again. If the path MTU discovery is still shown off, the registry may need manual editing, this is beyond our scope. Advise the customer of the problem and the need to have fixed or their ADSL service may have problems.

This may just be internet congestion but unlikely in my experience. Usually this is caused by too small a TCP receive window size (likely) or a small MTU size (less likely). The Windows default TCP receive window size is simply inadequate for broadband services. Especially when you consider typical latency we encounter accessing overseas sites from Australia. I performed some experiments downloading a large file from a typical US based site (Adobe) and noted the following results with a 1536/256kbps service, draw your own conclusions !!

RWIN size and notes	Transfer speed (kbyte/sec)
8k (Windows 95/98/ME default)	22
16k (Windows 2000 default)	43
32k	86
96k	155

Recommended MTU size is 1454, receive window size recommendation vary depending on what speed service the customer is using. Modem accelerator software tends to mess these settings up big time !!!. Significant performance gains can be made by tweaking these settings. Use the tweak test on this page http://www.dslreports.com/tweaks to check existing settings. Receive window size should be a multiple of the MSS for maximum effectiveness, the tweaks below are all multiples of a MSS size of 1414.

For MTU set at 1454 (see item 2 above)		Windows RWIN patch files (windows defaults shown in brackets)
Service Speed	Recommended Receive Window Size	Windows 98/ME (8k)	Windows 2000 (16k)	Windows NT4 (???)
256kbps	16k	rw98-16.reg	rw2k-16.reg	rwnt-16.reg
512kbps	32k	rw98-32.reg	rw2k-32.reg	rwnt-32.reg
1.536Mbps	96k	rw98-96.reg	rw2k-96.reg	rwnt-64.reg (largest)
Download PMTU registry patch if needed		PMTU registry patch file (Windows 98/ME only)

This seems to be related to the Enternet v1.3 software and Windows 2000 only. Advise customer to remove Enternet v1.3 then reboot and install Enternet v1.4.

ADSL customers can download directly from the Big Pond update site at ftp://update-server.vic.bigpond.net.au/dist/enternet/. Save this to disk and make sure you remove version 1.3 and reboot before installing 1.41.

Some Windows 2000 users experience a problems where they authenticate but cannot browse or ping anything after upgrading to 1.41. Try changing the advanced settings from "Private API" to "DHCP". To get display this setting, from the "Profiles" box click on "Connections", "Settings", then "Advanced".

5. Windows 98 second edition locks up or fails to shutdown correctly after PPPoE client has been installed.

6. "Error 43P Server Communications Error" and "Failed on Create Device" error messages.

These errors seem to be caused by NTS PPPoE adapter failing to bind properly during installation. To fix follow the directions here in the NTS Enternet FAQ.

The installation of a PCI NIC (network interface card) may be problematic in some customer PC's. The PCI specification allows for IRQ (interupt request line) sharing for devices on this bus, however poorly written drivers of one device may interfere with the other device. As a rule avoid sharing IRQ's with video card and hard drive controllers as these devices are often most troublesome. Also avoid having more than 2 devices sharing the one IRQ.

You can view the hardware PCI device listing and IRQ assignments on most PC's just prior to boot. Pressing the pause/break key at the right moment when the table is displayed will allow you to view it. Alternately insert a non-bootable floppy disk (the NIC driver disk is a good choice) in the floppy drive. This will also stop the PC at the point where you can view the PCI device listing table.

On most motherboards the first PCI slot shares the same IRQ as the AGP (graphics card) slot. Try avoiding changing bios settings on customers PC's as this creates a precedent for Telstra having to support the customer's hardware.

In order to overcome a hardware conflict the options are in order of preference.

(c) Install alternate ethernet hardware if possible - the four options are the SMC 1211TX card, 3COM PCMCIA card, SMC USB Adaptor or ISA card. The ISA NIC card is reported to have a very good strike rate in fixing these problems (in boards that have an ISA slot!).

PCI NIC card installation can sometimes be problematic in Windows 95 due to a less than complete implementation of plug and play. Installation of a ISA NIC card is often a better choice when working with a Windows 95 PC.

Remember USB is not supported on Windows 95 and NT4. The SMC USB adapter is also not supported on Apple PC's.

We have noticed problems with the USB ethernet adapter when used with some VIA technologies motherboard chipsets. The problem causes the USB adapter and other USB devices to stop functioning at random. If the customer is using a VIA Technolgies chipseted motherboard, install the VIA USB filter driver patch to fix this.