Multiple PVC's with Conexant PCI ADSL Modem

Posted on 2004-08-14
Last Modified: 2013-12-14
We use a Windows 2000 machine as our primary gateway to the internet and this server has a simple PCI ADSL modem whose chipset is made by the so-called vendor Conexant. It says that the device supports multiple PVC's (Up to eight) and I believe it could, however; when this theory is put onto practice, I could not see a "means" of establishing that.

We have PVC 0/35 assigned for us, to connect to internet over PPP. We asked the service provider if they could assign another PVC for us from which we could directly connect to our branch office. They told us that they assign PVC 8/32 for LAN emulation (Classical IP over ATM), and we agreed on that.

Now we have two PVC's; one for PPP and the other for LAN emulation. When we configure the ADSL modem with the new settings, it adds a ADSL LAN adapter which works fine, however; the former PPP conection now is uninstalled.

This way we cannot use multiple PVC's at the same time with our Taicom Mc8000p PCI ADSL modem which uses standard AccessRunner Conexant chipset.

Any help would be appreciated...
Question by:pheriplex
LVL 12

Expert Comment

ID: 11804972
Since your telco is offering ethernet emulation why do you want ppp?
I have not seen a SOHO class dsl modem capable of different encapsulation service at the same time. DSLAM configuration does not allow this either.

Author Comment

ID: 11811611
Indeed many DSL routers offer having up to 8 different PVC's each with different encapsulation at the same time. While one PVC is used for internet transmission, the other PVC will connect us to our branch office through a local network (LAN emulation over ATM):

- The PVC 0/35 is the "standard" PVC that is assigned for public. PPP over Ethernet encapsulation is required to connect to internet and the IP is assigned dynamically.

- The PVC 8/32 will connect us to our branch office directly, which is located in the same DSLAM area. Through this channel, no other host will interfere with our connection. It is the same approach of getting a leased line service from one area to the other although it is much less expensive, since the communication takes place through standard telephone lines.

The problem is that, we do not want to deploy an ADSL router, since our we do all routing through our Windows 2000 server. Instead, the internal ADSL modem is used for uplink connection.

Since many PCI ADSL modems use the same Conexant chipset, I thought it would easy for us to set it up, however; neither Conexant nor the modem manufacturer helps us anyway. We will use two PVC's "concurrently" and the modem "has" support for it. Here is the part which deals with ATM PVC's in the configuration file which is used to install the modem:

;0 = Independent PVC connection(s)
;1 = Multiple PVCs with bridge learning
;2 = SVC
;3 = Concurrent PVCs and SVCs

;max number of defined PVC's (0-16)
MaxPVC=1 ** We set this to "2"

;max number of concurrently active PVC's
ConcurrentPVC=1  **Also this to "2"

And we supply the correct PVC and encapsulation information this way;



;0 = PPP over ATM VCMUX (RFC 2364) (PPPOA)
;1 = PPP over ATM LLC (RFC 2364) (PPPOA)
;2 = Bridged IP over ATM LLCSNAP (RFC 1483)
;3 = Routed IP over ATM LLCSNAP (RFC 1483)
;4 = Bridged IP over ATM VCMUX (RFC 1483)
;5 = Routed IP over ATM VCMUX (RFC 1483)
;6 = Classical IP over ATM (RFC 1577) (IPOA)
;7 = Native ATM
;8 = RFC_PPPOE_VCMUX PPP over Ethernet VCMUX (RFC2516)
;9 = RFC_PPPOE_LLC PPP over Ethernet LLCSNAP (RFC2516)
;-1 = Proprietary


With this configration, the wizard normally should install one "LAN adapter" for PVC2, and one PPPoE connection for PVC1. However; the wizard only installs the first and leaves the second.

A modem which supports "multiple PVC's" concurrently should do what we want, and each and every modem in the market features this option. However; no vendor has written any detailed information about how to set-up concurrent PVC's thinking that no "one" would ever wish to use this feature they "proudly" advertise in technical specifications.

Certainly, the vendors are not lying, but the drivers they supply are so low-quality that without enough information, it is impossible to configure the modem correctly.

Until we decide to send the modem to trash and purchase a new ADSL router, and painstakingly reconfigure our ethernet environment, I hope that I will be able to find a solution...


Accepted Solution

byteria earned 140 total points
ID: 11827167
I think this configuration posted here is a broadband INS definition that contains the info about the DSL provider. Conexant-chipsetted modems normally use a wizard that first installs a device named "PCI arbitration device" and then binds a network adapter to it, which is either Conexant ADSL LAN adapter or Conexant ADSL WAN adapter. So in no way can both be installed at the same time.

Even if it says more than one PVC can be installed at a time, the problem lies not in the hardware device itself but the device drivers. I can only recommend you to purchase a 4-port ADSL router which contains the feature you request at this point.

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