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| | | | FAQ Revisions | Editors: Flippant  , d_l , lev
Last modified on 2009-08-07 20:46:13
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3.1 Speedstream 5100b & 4100·What do the hybrid numbers mean and what do they tell you about your line?
·How do I access the modem GUI thru a router - advanced methods?
·How can I fix the broken power switch on my 4100 modem?
·How can I access the Speedsteam modem's CLI?
·How can I use the cfg command on the Speedstream modem?
| | | Hybrids explained.
The hybrid numbers reported in the log for the 5100b/4100 modems, »192.168.0.1/log.htm, indicate which hybrid of four choices the modem has chosen to complete its sync. A hybrid is an electrical circuit that acts as an analog echo canceller. It subtracts the locally transmitted signal (the upstream side) from the receive path. By using multiple hybrids that can be switched in or out, or combined, the modem can more closely match the impedance of various in-home wiring topologies and bridged tap conditions resulting in improved echo rejection.
The modem makes its signal to noise measurements for each of the four hybrids during the sync training period to determine the optimum hybrid for the loop conditions. Within a fraction of a second the best hybrid is chosen.
Although the switchable hybrid technology can significantly improve performance under bridged tap conditions, it cannot completely cancel out the adverse affects of bridged taps. The reason is that bridged taps also can cause impedance nulls in the middle of the downstream spectrum where the hybrid circuitry is not effective. These impedance nulls result in reduced bit loadings in those tone bins and greatly reduce the maximum attainable sync speeds.
The loop conditions detected by the hybrids.
The Texas Instruments AR5 was the multi-chip predecessor to the AR7 chipset that is used in the Siemens 5100b/4100 modems. The AR7 chipset has the four hybrids directly integrated into the chipset circuitry unlike the AR5 in which they had to be added to the modem motherboard as separate chips. The following direct quote is from a white paper on the Westell 2200 modem which uses the AR5 chipset:
The 4 hybrids optimize performance on the following loop topologies:
• Hybrid #1 - Standard Hybrid: Straight Cable without bridged taps
• Hybrid #2 - 0-1000' Bridged taps or in home wiring tap located 0 to 50' from modem
• Hybrid #3 - 0-1000' Bridged taps or in home wiring tap located 50'-250' from modem
• Hybrid #4 - 0-1000' Bridged taps or in home wiring tap located 250'-1000' from modem
Note that the explanations for hybrid numbers 3 and 4 have been swapped from their original order as published by Westell. Several lines of evidence including this thread: »[Line Problem] Cant upgrade but im close enough suggests that they were erroneously transposed in the white paper. It is unlikely that inside wiring could separate an in-home bridged tap 250'-1000' from a modem, but separation of 50'-250' seems possible.
So what could this mean about my line?
Note: The following information is not valid for the 4100b modem. The revision of the printed circuit board and components in the 4100b and/or the change to a7.00.02.00 firmware in the 4100b has modified the operation of the various hybrids with respect to the line conditions and impairments. Hybrid #3 seems to indicate normal line conditions on a 4100b modem.
The interpretation of hybrids depends on whether the modem is plugged inside or at the NID jack, so if your modem is reporting:
Hybrid #1 - The line is a straight loop and has no detectable bridge taps. This is the normal hybrid.
Hybrid #2 - Usually due to in-home wiring. This hybrid reading is commonly seen in newer homes with star topology wiring (multiple CAT5 wiring runs connected to the NID) without a POTS splitter. It can also be caused by older, daisy-chained, inside wiring if the modem is connected to a jack in the middle of the chain.
Hybrid #3 - May be caused by a bridge tap(s) outside of the building; however, there have been instances of a hybrid #3 bridged tap located within in-home wiring. Note: Inside hybrid #3 readings have also been caused by microfilters, POTS splitters, and alarm filters in the NID.
Hybrid #4 - May be caused by a bridge tap(s) on the loop.
Hybrid numbers 3 and 4 are relatively rare conditions, and if caused by a bridged tap, the line's attenuation would be increased and its maximum attainable speeds severely reduced. In one instance, an inside hybrid #3 bridged tap reduced the loop's potential speed down to 35% or less of its maximum attainable level.
What should you do if you have a DSL line problem?
The hybrid used by the modem should only be a concern if there are problems such as excessive CRC error rates, abnormally low maximum sync capacity, or low noise margins (below 8.0 dB). If the DSL line is problem free, then the hybrid used really doesn't matter.
If you are having a line problem (low sync speeds, sync instability, high CRC rates, etc.) AND the modem is reading any hybrid other than #1 in the log, you MUST run a NID test with your modem connected directly to the test jack to see if the hybrid number changes from the inside readings. See the following FAQ for additional information concerning NID tests: »AT&T Southeast Forum FAQ »How to check modem stats, synch rates & speeds from test jack at the NID.. A change in hybrid numbers indicates that the bridged tap condition is due to in-home wiring complexity and may need to be fixed by a POTS splitter-home run installation if the inside wiring is reducing sync speeds or causing line errors.
If the hybrid number is the same at the NID as inside, then the line condition is outside the residence. In some rare instances, the modem will report a hybrid #3 at the NID due to other line conditions (wire gauge changes, splices?) and not due to bridged taps. These non-bridged tap, hybrid #3 readings are not accompanied by any other line problems.
Once you have completed the NID test, the techs in the AT&T Direct forum should be contacted about your line problems. You can post your hybrid numbers and line stats for both the inside and NID tests there. They will verify the modem's readings and possibly schedule a tech visit.
If the modem reports alternating use of Hybrid #1 and #2 between repeated sync drops, this would indicate that your line has an intermittently failing POTS splitter: »[General] HYBRID 2 and HYBRID 1. When a POTS splitter fails, the modem will see the home run as an in-home bridged tap and report Hybrid #2 if it is even capable of syncing.
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by d_l
last modified: 2009-04-06 14:20:04 | | | The simplest and cheapest method of accessing the 5100b/4100/4100b modem GUI through a router is explained in the section "Let the modem do the PPP and issue a public/private IP to wan/internet port of router" at the bottom of the page here: »Ameritech - SBC FAQ »Funhouse 5100b Setup and Reference Info and for the Motorola 2210 modem the explanation is here: »Ameritech - SBC FAQ »Modem GUI access with a router ; however, sometimes there can be disadvantages to allowing the modem to make the PPPoE connection such as problems with some on-line games or P2P traffic.
An alternate method of accessing the modem's GUI when a router makes the PPPoE connection can be set up by inserting an inexpensive five-port switch (or hub) between the modem and the router. This works because the PPPoE-encapsulated traffic "tunnels" directly from the router through the switch to the modem without problems, but any other non-PPPoE-encapsulated traffic on the the 192.168.0.x subnet will be directed by the switch to the modem's GUI. Note: That this arrangement with appropriate IP adjustments can also be used for modem models other than the 5100b/4100/4100b or 2210.
So what other type of ethernet connections can be made to the switch to access the modem?:
Method 1: A computer off the LAN and dedicated to the collection of modem stats could be set up.
Method 2: A computer on the LAN, but with a second NIC set to the 192.168.0.x subnet could be connected to the switch.
Method 3: A second router in parallel with the primary router that bridges the 192.168.0.1 traffic.
This secondary router can be an old unused unit or it could be a wireless router that also adds wireless connectivity to the LAN. Both routers are assigned IPs on a subnet that isn't 192.168.0.x or 192.168.1.x. The DHCP function on the second router must be disabled. A patch cable connects a LAN port on the primary router with a LAN port on the secondary router.
In the following diagram, the primary router is set to make the PPPoE connection. The secondary router should be set to "Obtain an IP automatically" if the modem is in "PPP on the computer" mode or set to the static IP of 192.168.1.64 as stated at the bottom of this FAQ: »Ameritech - SBC FAQ »Funhouse 5100b Setup and Reference Info if the modem is in the "Bridged Mode".
From the command prompt, you must then run the following command for each LAN computer that is to access the modem GUI:
route -p add 192.168.0.1 mask 255.255.255.255 A.B.C.Y metric 5
The "-p" option make this routing persistent even after a computer reboot. The A.B.C.Y IP is the secondary router's IP. This command line could also be placed in a BAT file to be run as necessary.
The command: route delete 192.168.0.1 will erase the routing from the computer permanently if needed.
The background for this portion of the FAQ was derived from the discussions in this thread: »Viewing Modem Stats? Thanks to Bill_MI for the router set up details.
Method 4a: A connection from the router's switch to the five-port switch without the secondary bridging router.
The router is set to make the PPPoE connection. A patch cable connects a LAN port on the router with a port on the five-port switch. The computer's NIC is set to a wider mask than the typical 255.255.255.0 mask. The diagram shows it set to 255.255.0.0, but this could be restricted to 255.255.252.0 if there is some need to do so such as to allow connections through a VPN to other 192.168.x.x subnets.
Note: This method should only be used with static IPs on the LAN or with the modem's DHCP server disabled. The modem's DHCP server can be disabled by bridging or by accessing the CLI: »SBC DSL FAQ »How can I use the cfg command on the Speedstream modem?. Unintended routing results occur if the router is set up as a DHCP server and the modem's DHCP server is still active. For example, a DHCP client device on the LAN can end up with the 192.168.1.64 address issued by the modem's DHCP server instead of the intended address.
Although this method requires less equipment than the other methods, it does produce slightly more traffic activity on the LAN. All the LEDs on all the equipment that show ethernet activity will blink simultaneously and the router logs might show false "intrusion" attempts on the WAN from the computer and modem broadcast traffic.
On occasion certain LAN devices can lose the path through the switches to the gateway router, 192.168.2.1, and packets will end up attempting to pass into the WAN port of the router. A router logging program could record this as an "attack" by your LAN device on your router. If this happens, either temporarily unplug the patch cable connecting the router port with the 5-port switch or disable the port through the router's GUI (if this option is available), then reboot the problem device and/or 5-port switch as necessary to restore the proper path to the router's switch side.
The method was modified from the discussions in this thread: »switching to dslextreme - question on setup. Thanks to sded for the ideas.
Method 4b: A connection through the router's switch without requiring the separate five-port switch of Method 4a.
Follow the directions and note given for Method 4a. The one drawback of this method, of course, is that it uses more wired ports, but if a wireless router is used, this may not be such a problem. The packet path stability of this method is unknown and it may require some manual attention on router reboots.
The method was suggested by S_D .
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by d_l
last modified: 2009-06-08 14:29:52 | | | First of all if your modem is less than one year old, it is under warranty and you should contact AT&T for a replacement.
This FAQ is only for off-warranty 4100 modems with broken power switches that would otherwise be useless paperweights. If it is dead, then nothing you do to it will damage it any more, right? This is desperation modem surgery.
1. With the modem totally unplugged, remove the Phillips screw on the bottom of the modem. Then insert a thin screwdriver or knife blade between the top and bottom halves of the case and gently pry them apart. There are four corner tabs clipping the modem halves together and a plastic hinging latch and tabs on the front that must be separated. It is best to work from the back corners to the front unhooking the four tabs. Once the four tabs have been unclipped, the modem halves will hinge open and the front latch and tabs will unhook easily.
2. Then remove the modem printed circuit board (PCB) from the bottom half of the case by lifting the front corners of the PCB with the blade.
3. Flip the PCB over and locate three pins in a row soldered to the opposite side of the PCB from the power switch. The three pins are circled in red on the photo.
4. These pins must be bridged with solder to short-circuit the broken switch as shown below.
For the first test of this revival method, the power switch was gently pulled from and twisted off the PCB with needle-nosed pliers as shown below, but this step is believed to be unnecessary for reviving the modem.
5. Then replace the PCB back in the case, snap the halves together, and insert the screw. Your modem should work properly once it is powered up.
Since you have shorted the power switch, the DC-power supply, barrel connector can now be used to power cycle the modem.
A special thanks to guhuna for beta testing this modem revival method and providing the photos of the soldered switch pins and the pulled switch.
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by d_l
last modified: 2007-11-12 19:38:02 | | | This command line interface (CLI) access method can be used on AT&T-versioned 5100b, 4100, and 4100b modems.
1. You need to download a copy of ICGabe 's password injector applet: SpeedStream5200FTP.exe at »www.gabrielstrong.com/. Read the instructions carefully. The applet requires an installation of WinPcap to work: »www.winpcap.org/install/default.htm. If you have ever used Wireshark (formerly known as Ethereal), then you already have a version of WinPcap installed.
2. The use of SpeedStream5200FTP.exe with the Speedstream CLI must be made with a direct connection to the modem and after either a hard reset or a GUI reset (not a GUI restart) has been performed. This will reset the modem back to factory default settings. The reset should be done without a phone line connected to the modem. After the reset, you should test for telnet access to the modem. This is just a functionality test. You won't be able to get past the log-in password.
Exit telnet and run SpeedStream5200FTP.exe with the MAC from your NIC and modem and a short ID and password. The applet will "inject" a temporary ID/password of your choosing using SNAP into the modem. Your new ID/password has a short time limit (a few minutes) on it and after that time limit expires, you will be locked out of any new telnet log-in sessions on the modem. The applet may be re-run to provide another interval of temporary access if you are ever locked out.
Run telnet once again and this time you should be able to log-in using your chosen ID and password and reach the command line prompt (xsh>).
3. If you plan on doing any repeated telnet sessions, you will need to replace that temporary log-in ID/password with a more "permanent" ID/password. The commands to do so are listed in line-by-line notation. Enter them at the command line prompt (xsh>):
cfg upro#0{usr{un="logon"
cfg upro#0{usr{pw="password"
cfg upro#0{usr{per=0xffffffff
cfg save
do reboot
... or they can be entered in combined-line notation as:
cfg upro#0{usr{un="logon",pw="password",per=0xffffffff
cfg save
do reboot
Substitute your own ID/password for "logon" and "password". The ' " 's should be used to enclose your entries. You can re-use the same ID and password as you used in the SpeedStream5200FTP.exe applet. The modem responds to the "cfg save" entry with a note that the settings are written to NVRAM. The "do reboot" entry reboots the modem. Hyperterminal can be used instead of telnet for its accurate entry, cut-n-paste, capabilities to enter the commands one line at a time.
After the modem has rebooted, you can now telnet back into it repeatedly for an unlimited time with your new ID/password.
Remember, once you actually use the modem, e.g. transfer anything through the ATM circuitry, your access to the CLI is then locked out. All setting changes you have made will be retained until you make another hard or GUI reset. Also your new password is now your new modem access code.
Now that you can access the command line prompt, you will want to read »SBC DSL FAQ »How can I use the cfg command on the Speedstream modem?.
**** If you don't like any settings you've changed after a reboot, a hard reset erases all changes, and restores the standard AT&T factory settings. ****
A special thanks to ICGabe , Doctor Olds , odinb , wayjac , and many others for originally working out and posting many aspects of this access method. This FAQ would not have been possible without their work in this thread: »Difference between 4100 and 5100
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by d_l edited by lev
last modified: 2008-06-10 11:35:36 | | | The AT&T Speedstream modems retain the full router functionality of the generic-version modems, but the user is "shielded" from this functionality by the AT&T-versioned GUI software. The 5100b/4100/4100b modems have hidden tricks that can be unleashed by use of the CLI. Any setting changes you have made at the CLI are retained until you either hard reset or GUI reset the modem back to factory defaults. So it is a set-once-and-forget situation. Remember, after you use the modem, e.g. transfer anything through the ATM circuitry, your access to the CLI interface will be locked out.
So if you decide that you want to change a CLI setting slightly after you have made a DSL connection, all custom settings will be erased by another hard reset before you can re-gain CLI access. The exceptions to this "use the modem and have to reset to change CLI settings rule" are any CLI settings that correspond to those on the AT&T GUI setting pages. If you have changed those settings at the CLI and you later decide that you want to alter them, you may use the GUI pages to make changes.
After the command line prompt (xsh>) has been accessed: »SBC DSL FAQ »How can I access the Speedsteam modem's CLI?, the four main command categories: do, clear, show, and cfg, may be listed by entering a "?". This FAQ will only deal with the "cfg" sub-commands.
No user manual has been published for the functions or operations of the CLI commands. The commands listed in this FAQ have been worked out by trial-and-error. Many of the "cfg" commands directly correspond to GUI functions listed in the generic 4100/4200 user manuals so their functions can be inferred by cross checking with that user guide.
The entire modem configuration (cfg) command set and the current settings of the first choice of any multiple sub-command may be listed or dumped out at any time by entering just the "cfg" command at the CLI prompt (xsh>). You can drill down to the current settings for any level by entering the entering just the first portion of the sub-command for that layer, e.g. entering "cfg upro#0{usr{per=" would list the current password.
To change any setting, simply enter the "cfg" sub-command at the command line prompt, followed by "cfg save". The modem will acknowledge the command with a note that the settings have been saved to NVRAM. Then enter a "do reboot" command and the modem will enter the reboot cycle and use the new command.
Finally after you have finished all setting changes that you plan to make, you may have to access the modem GUI and change the PPP location to fit your situation. It will always be set to the default "PPP on the modem" after the hard reset/GUI reset you originally performed to enable the CLI access. Also your new password is now your new modem access code.
Some useful "cfg" sub-commands
Change the modem's IP: The following example lists the commands necessary to change the modem IP, gateway IP, and the DHCP-issued IP. At the command prompt, enter the following commands with your chosen IPs changed from the listed default values:
cfg host#0{ip{addr=192.168.0.1},dhcp{ip1=192.168.1.64,ip2=192.168.1.64,gw=192.168.0.1}
cfg ipfw{dip=192.168.1.64}
...and remember to follow up by entering:
cfg save
do reboot
After the reboot, you will have to use the new IP to access the modem with telnet or HyperTerminal. Also the IP settings in your NIC and any software firewall that you use might have to be changed/adjusted to allow access to the modem on the new IP.
Change the timeservers to AT&T-maintained servers:
cfg sntp{psrv="ntp1.sbcglobal.net",bsrv="ntp2.sbcglobal.net",tz=0
The "tz" setting adjusts the timezone offset from GMT and is specified in minutes, e.g. PST equals -480
Enable the built-in DDNS client:
cfg ddns{sn="members.dyndns.org",spo=443,hn1="test.homeip.net",un="test",pw="test",en=y
The hostname (hn1), username (un), and password (pw) are set to a DynDNS testing account provided for client testing during the client development process. You should substitute your own name, ID and password and retain the ' " 's around your entries.
Warning: This client will update DynDNS, but could engage in abusive updating which could result in your hostname being temporarily blocked by DynDNS. The client for this modem is not on their certified list; however, Doctor Olds has used the built in-DDNS updater on the generic version of the 5100b modem at DynDNS without problems.
Send the syslog to port 514 of a designated IP:
cfg slog{ip#0=xxx.xxx.xxx.xxx,esl=y
xxx.xxx.xxx.xxx is the IP of the computer that is to monitor the port 514 output. You will then need to run a syslog analysis program on the monitoring computer. The idea for using this command originated with Frobozz here: »SpeedStream 4200 Syslog Output Method
Write DSL statistics into the modem log every X+1 seconds:
cfg dsl{log=X
X is the number of seconds between write intervals. One extra second will be added to the X interval time by the modem. If X is set to zero (the default setting), this extra logging function is disabled.
The modem log eventually will fill up and the oldest stats will be pushed out of memory to make way for the newest. This command set could be useful to spot fast changing DSL problems. A sample of the statistics written to the log each sample interval are as follows:
+000 days 00:02:00 E |DSL |Connection : UP
+000 days 00:02:00 E |DSL |Re-sync Count: 1
+000 days 00:02:00 E |DSL |Mode: G.dmt
+000 days 00:02:00 E |DSL |DS Bit Rate: 6016000
+000 days 00:02:00 E |DSL |US Bit Rate: 768000
+000 days 00:02:00 E |DSL |DS Attain Rate: 6016000
+000 days 00:02:00 E |DSL |DS SNR: 13.5
+000 days 00:02:00 E |DSL |DS Atten: 31.5
+000 days 00:02:00 E |DSL |DS Output Power: -
+000 days 00:02:00 E |DSL |US Attain Rate: -
+000 days 00:02:00 E |DSL |US SNR: -
+000 days 00:02:00 E |DSL |US Atten: -
+000 days 00:02:00 E |DSL |US Output Power: -
Force the RT to sync up in ANSI mode:
cfg dsl{mode=ansi
CO DSLAMs can not be forced into ANSI mode. This command does not work for 4100b modems.
Disable the modem DHCP server:
cfg host#0{dhcp{en=n
This will disable the DHCP server even when in PPP on modem or PPP on computer mode and is necessary when accessing the modem by Method 4 of »SBC DSL FAQ »How do I access the modem GUI thru a router - advanced methods?.
More useful commands will be added to this FAQ as they are discovered.
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by d_l
last modified: 2009-03-19 12:21:25 |
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