Problems with the V.FC protocol and upgrading to V.34 using the Rockwell RC288ACL/VFC Chipset Compiled by BWANA 12/24/94 There is come confusion about what exactly the problem is upgrading to V.34 if you have a modem that was built with the Rockwell Chipset. This Chipset is indentified as either one of Following RCL288ACL/VFC RCL288ACI/VFC This text was not compiled to tell the V.FC users waiting for a ROM upgrade they are DICKED. This text is for information and an explination of why some people can't get a respectable connect to some Bulletin Boards. It will also deture confusion about what is happening with the V.FC rom upgrades. There is a file cirrculating that contains a message from a Ronald Jones to a Paul Haake that is a part of a captured thread running on the USR and HAYES mother boards. I have followed this disscusion with great interest and was in agreement with Paul until his last statement. The problem is not with RETRAINING as he suggest. All MODEMS from V.32, V.32bis etc all the way up the line to the V.FC and V.34 RETRAIN. This is a FACT because it is a requirement of the ITU-T study group which was set in the V.32 standard in April of 1988 The group known then as the CCITT sets the standards for all of the telecommunication industry. Any deveation from this standard means you have a PROPRIETARY modem. Examples are the HST 14.4/16.8, the Trail Blazer, The Compucom SPEEDY modem, and the Hayes V Series. All of these companies designed modems that worked pretty well. There was just one catch. They would only communicate with another modem EXCACTLY the same kind. Any attempt for a HAYES V Series to communicate with a HST (not the Dual) would result in a 2400bd ARQ/MNP connection In August 1994 the ITU-T set the standard for the newest and probably the LAST standard, at least on normal phone lines, the V.34 standard. This standard is backward compatable down to Bell 103 or 300bd. It includes communication with V.FC or the F.Fast Class standard as proposed by Hayes and Rockwell Int. back in July of 1993. The problem is not RETRAINING but the LINKING of a V.FC calling a V.34. The problem occurs because the Rockwell chip sets do not support the Spilt Speed at the initial link. When a V.FC calls a V.34 the answering modem will determine which link gets the higher speed coming or going no matter what. A V.34 modem will see a dual link speed such as 26400/28000 meaning a connection of 26400 recieve and a 28000 transmit. A V.FC may see a 24000 connect but the recieving V.34 is seeing a 24000/19200. Here is where the problem comes in. The Rockwell chipset has no way to use the split channel with the exception of the back channel select which must be done before the call is made with the %Fn command. The RC288ACL/VFC chipset does not support the modulation of the V.34 requirement. If the V.34 choses the slower speed, even though the V.FC is transmitting at a higher rate, too bad. This problem is compounded if the phone lines are not the best they can be. Another problem is the support hardware, firmware of some of the V.FC modems. A Hayes ACCURA is not the same as a Hayes OPTIMA. Just as a Hayes OPTIMA is not the same as a Hayes ULTRA. This also stands true for other modem manufactures. A USR Courier, either a DUAL or a plain courier is not the same as the Sportster. There is extra filtering and support firmware in the higher end modems. Comparing a ZOOM 28.8 V.FC to a Courier or a ULTRA is like comparing a FORD ESCORT to a MUSTANG COBRA GT 500. **************** V.34 Handshaking The modem defaults to V.34 and tries for the highest possible speed when it attempts to connect with another modem, 28.8K bps. The entire V.34 range comprises 28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K, 9600, 7200, 4800, and 2400 bps. If the remote modem is not V.34 capable, a connection is made using the highest compatible modulation scheme (V.FC, V.32 terbo, V.32 bis, and so on, down to as low as Bell 103, or 300 bps). If the remote modem has V.34 capability, the two modems use a line probing technique to determine the highest speed possible under current line conditions, and complete the connection. If the remote modem does not have V.34 capability, a calling V.34 modem listens to the other modem's answer tones to identify what standard rate the remote modem is operating at, and adjusts to that rate. An answering V.34 modem sends out a series of answer tone signals until both modems can negotiate the best connection rate. ******************************** V. Fast Class (V.FC) Handshaking The modem defaults to V.Fast Class and tries for the highest possible speed when it attempts to connect with another modem, 28.8K bps. The entire V.FC range comprises 28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, and 14.4K bps. If the remote modem is not V.FC capable, a connection is made using the highest compatible modulation scheme (V.32 terbo, V.32 bis, and so on, down to as low as Bell 103, or 300 bps). If the remote modem has V.FC capability, the two modems use a line probing technique to determine the highest speed possible under current line conditions, and complete the connection. If the remote modem does not have V.FC capability, a calling V.FC modem listens to the other modem's answer tones to identify what standard rate the remote modem is operating at, and adjusts to that rate. An answering V.FC modem sends out a series of answer tone signals until both modems can negotiate the best connection rate. **************************************************** INFO taken from the Rockwell V.FC RC288ACL/VFC programers referance manual %Fn - Split-Speed Direction Select Determines which direction (transmit or receive) has the 75 bps channel, and which has the 1200 bps channel. This command is only valid if the \W1 command has been executed. BPS speeds are referance only %F1 Selects 75Tx/1200Rx. Resets S28 bits 1 and 2. (Default.) %F2 Selects 1200Tx/75Rx. Sets S28 bit 1 and resets S28 bit 2. ------------------------------------------------------------------------------- **************************************************** INFO taken from the ITU-T V.34 specification TECH manual The V.34 specificication implies that the modem DYNAMICALLY reverse channels during a transmission when the need occurs. The Rockwell chip set does not have this ability above 9600bd. It is not listed anywhere in the RC288ACL/VFC programers referance manual. With out this ability the modem will have to maintain an equal back channel. If the slower channel is the Proprietary channel this is what you will live with. There is no way to determine which will be the faster channel. ------------------------------------- The following are USERSTAT PPE PCBOARD captures from the USR BBS. 1 is a V.FC user and the other is my own modem. Look at the differances in the coding and carrier frequency. Also note the Trellis modulation of a V.34 modem as compared to a V.FC. I beleive this user has a Hayes Accura. The Hayes users are using the USR BBS just to get these results from the USERSTAT PPE. The Hayes series modems do not have the ability to perform this line diagnostic while online. This V.FC user has about the same line noise etc as I do so he should get a similar connect. However he is at 19.2 with out the split channel. If DA-BONE gets this PPE operational on the DNTA board you can see just how it is in REAL LIFE. =============================================================================== Date: 10-12-94 Time: 03:41p Number: 54099 From: USRSTATS PPE Refer: 0 To: MIKEJ RYAN Board ID: USR-USA Recvd: Yes Subject: Modem Status Report 0: Main Board Status: Public ------------------------------------------------------------------------------- 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � Protocol LAPM � Modulation V.FC � � Compression V42BIS 2048/32 � Speed 19200 � � Link Timeouts 0 � Carrier Freq (Hz) 1920/1920 � � Link Naks 0 � Symbol Rate 3200/3200 � � Blers 0 � Retrains Requested 0 � � Blocks resent 0 � Retrains Granted 0 � � Chars lost 0 � Fallback Enabled � � Chars sent 9216 � HST Line Reversals 0 � � Chars Received 0 � HST Equalization Long � � Blocks sent 437 � Trellis Code 32S-2D/32S-2D � � Blocks Received 60 � Nonlinear Encoding OFF � � Octets sent 5705 � Precoding ON � � Octets Received 69 � Shaping OFF � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Preemphasis Index 4/3 � � USRSTATS Version 3.04A � Rx/Tx Level (-dB) 33/17 � � Current Call 00:04:07 � Roundtrip Delay mS 32 � � 10-12-94 15:40 Caller 335730/1 � SV: 09/15/94 DSP: 09/09/94 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 旼컴컴컴컴컴컴컴컴컴커 � -26 � � � � � � � � � -28 � � � � � � � � � -30 � � � � � � � � � -32 � � � � � � � � � -34 � � � � � � � � � -36 � � � � � � � � � -38 � � � � � � � � � -40 � � � � � � � � � -42 � � � � � � � � � -44 � � � � � � � � � -46 � � � � � � � � � -48 � � � � � � � � � 읕컴컴컴컴컴컴 � � 1 3 3 3 3 3 � � 0 0 3 3 4 6 � � 2 2 2 7 7 2 � � 5 5 5 5 5 5 � 읕컴컴컴컴컴컴컴컴컴켸 =============================================================================== Date: 12-23-94 Time: 11:01p Number: 65115 From: USRSTATS PPE Refer: 0 To: TIM SCOTT Board ID: USR-USA Recvd: Yes Subject: Modem Status Report 0: Main Board Status: Public ------------------------------------------------------------------------------- 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � Protocol LAPM � Modulation V.34 � � Compression V42BIS 2048/32 � Speed 26400/28800 � � Link Timeouts 0 � Carrier Freq (Hz) 1959/1959 � � Link Naks 0 � Symbol Rate 3429/3429 � � Blers 0 � Retrains Requested 0 � � Blocks resent 0 � Retrains Granted 0 � � Chars lost 0 � Fallback Enabled � � Chars sent 3072 � HST Line Reversals 0 � � Chars Received 0 � HST Equalization Long � � Blocks sent 182 � Trellis Code 64S-4D/64S-4D � � Blocks Received 53 � Nonlinear Encoding ON/ON � � Octets sent 2267 � Precoding OFF/ON � � Octets Received 53 � Shaping OFF/OFF � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Preemphasis Index 6/6 � � USRSTATS Version 3.06 � Rx/Tx Level (-dB) 31/14 � � Current Call 00:00:57 � Roundtrip Delay mS 40 � � 12-23-94 23:01 Caller 412135/8 � SV: 12/02/94 DSP: 12/02/94 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � -24 � � � � � � � � � � � � � � � � � � � � � � � � � � � 0 � � -26 � � � � � � � � � � � � � � � � � � � � � � � � � � � 2 � � -28 � � � � � � � � � � � � � � � � � � � � � � � � � � � 4 � � -30 � � � � � � � � � � � � � � � � � � � � � � � � � � � 6 � � -32 � � � � � � � � � � � � � � � � � � � � � � � � � � � 8 � � -34 � � � � � � � � � � � � � � � � � � � � � � � � � � � 10 � � -36 � � � � � � � � � � � � � � � � � � � � � � � � � � � 12 � � -38 � � � � � � � � � � � � � � � � � � � � � � � � � � � 14 � � -40 � � � � � � � � � � � � � � � � � � � � � � � � � � � 16 � � -42 � � � � � � � � � � � � � � � � � � � � � � � � � � � 18 � � -44 � � � � � � � � � � � � � � � � � � � � � � � � � � � 20 � � -46 � � � � � � � � � � � � � � � � � � � � � � � � � � � 22 � � -48 �*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*�*� 24 � 쿗evel읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�Atten� � 0 0 0 0 0 0 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 � � 1 3 4 6 7 9 0 2 3 5 6 8 9 1 2 4 5 7 8 0 1 3 4 6 7 � � 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 � � 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� SUMMATION: I won't bag on HAYES, ZOOM, or any of the other modems using the Rockwell Chipset. I make these simple observations that can be validated There are at least 5 people that call DNTA that have USR V.34 modems We all get a 26400/26400 connect or at least a 24000/24000 connects all the time. I call LD more than anyone else and I get as good or better connects than I do here. There is a definate problem with all the modem manufactures that used the RC288ACL/VFC or the RC288ACI/VCF chipset. I agree that if it were a simple ROM upgrade it would have been done by now. Supposing that it can be done with a ROM upgrade I think those of you that own a HAYES modem need to open it up. I can't speak for the ACCURA but the ROM on a OPTIMA is under a SOLDERED METAL SHIELD and is NOT USER upgradable. I can't picture anyone at Hayes attempting to let a NORMAL everyday user attempt this.