Using PPPoE with Alcatel STHome on Bezeq ADSL Network

21 November 2002, Doron Shikmoni

v1.02

The Problem

Bezeq (the Israeli PTT) has published ADSL installation instructions which require a PPTP VPN setup. This setup is easily configurable with various flavours of MS-Windows, but has its drawbacks. Among them are:

• It is typically viewed as an MS-Windows "thing" rather than standard (although it has been made into an IETF informational document - RFC2637).
• Reportedly, it is not always trivial to deploy a PPTP client in non-Windows systems.
• Perhaps most irritatingly, many of the low-cost gateway devices (home routers, LAN / WLAN broadbadnd gateway combos etc.) - particularly those brought in from the US - only have PPPoE (PPP over Ethernet, RFC2516) client support, and no PPTP client, so they appear to be unusable in the Bezeq scene.
  

I was mainly annoyed with this last issue. I got me a cute little gadget for pennies, which does WiFi and NAT and some lame firewalling and whatnot. Then I realized that it can't do PPTP, as Bezeq's installation instructions require. So apparently it can't be used in Israel?

Curiously, it turned out that common wisdom has it that the PPTP tunnel is required by Bezeq's gear. "Bezeq does not support PPPoE, maybe they will at some unknown point in the future", and there's actually little hope.

The problem appeared to be quite painful, so much that some agile dealers actually sold, for considerable amounts of money, "specialized" firmware updates for some of those boxes, only to add PPTP support to them "so they can work in Israel".

A simple solution is offered here, with which you can do away with PPTP, and use PPPoE, with the Alcatel SpeedTouch Home ADSL modem, today. No Bezeq intervention is required, no "hacking" is involved, and the process is quite straightforward.

Linux / D-Link / Linksys / Netgear / (other) users - I think you're gonna like this.

Basic assumptions:

• Bezeq ADSL Network
• Alcatel SpeedTouch Home

1. I don't know how to do this on the older Orckit box - I have the STHome. If I'll get the information, I'd be happy to add it to this page.
2. The Samsung AHT-E300 modems recently supplied by Bezeq are preconfigured to do PPPoE, out of the box, and do not need the receipe that's following (they apparently just do not support PPTP).
   

Obligatory Short Technical Explanation (skip to next section if not inclined)

The recommended setup of Bezeq ADSL uses a PPTP tunnel. This tunnel is used for authentication and traffic encapsulation - to pass the credentials (and IP traffic) of the user to the carrier, and from there to the ISP. The ISP receives the connection via an L2TP tunnel.

If you follow the installation instructions, you will notice that the remote end of this tunnel is 10.0.0.138.

This IP address is in fact the default address of the "modem" (its LAN interface). So, the PPTP tunnel actually terminates at the home device - rather than on the carrier's gear. This is key to understanding what we do here.

From the modem, and upstream into the carrier network, the user's credentials and packets flow over a different protocol - PPPoA (PPP over ATM). On the modem (assuming its default configuration), the PPTP tunnel called "RELAY_PPP1" is gatewayed to VPI/VCI = 8/48, which is the ATM Virtual Circuit where Bezeq does business (ISP long term subscribers). In a nutshell, the modem is the one to gateway PPTP into PPPoA.

Okay, this is interesting. What logically follows is that in order to use PPPoE and not PPTP, all it should take is to have the modem - not the carrier's gear! - gateway PPPoE (from the LAN) into PPPoA, on 8/48, and we'll be there.

This is exactly what the rather simple receipe below guides you through. Networking-wise, gatewaying PPPoE into PPPoA is a very simple task (they're both PPP after all). It's essentially just bridging.

So let's see how we make our modem bridge PPPoE into PPPoA.

Reconfiguring an Alcatel SpeedTouch Home to Work with PPPoE Instead of PPTP

Note 1: this receipe does not require "hacking" the modem, turning it into a "pro" model or anything low level like that. We'll use straightforward, documented features and configurations, and end up with straightforward PPPoE support.

Note 2: Once this procedure is completed, your ADSL connection should be ready to support PPPoE, but you will not be able to connect with PPTP. It is completely reversible, but keep this in mind so as not to lose a heartbeat when it happens.

Disclaimer: although I have successfully implemented the process described below, your mileage may vary, big time. When you try the following, you are doing it at your own risk. If in doubt, don't do it. In fact, if you have a Bezeq-owned modem (leased), I'm not sure how favorably Bezeq will view people reconfiguring it. I own my modem.

We'll assume the machine from which you are doing this is already connected to the modem and properly configured. If it's not, then connect it to the LAN (10Base-T) port of the modem. Let your machine use an address 10.0.0.x where x is not {0, 138, 255}. Any suitable mask will do. We'll further assume that the modem is more or less in its default configuration.

1. Start a browser and access http://10.0.0.138. You should get the Alcatel welcome page.
2. On the left hand selection menu, click PPTP. You should get the PPTP gateway page.

3. On this page, you should see a set of configured connections (usually 4).One of them is called RELAY_PPP1 which is at 8/48. DELETE it.

4. On the left hand selection menu, click PHONEBOOK. You should get the modem "phonebook " entries.

5. Find the entry for RELAY_PPP1 in the phonebook. DELETE it.

6. In the bottom of that screen, you will see an ADD feature. We'll add a new phonebook entry. Name it PPPoE. For VPI/VCI enter 8 and 48, and for type of entry select "bridge". Now click ADD. Click APPLY (top, left).

7. On the left hand selection menu, click BRIDGE. You should see the bridging configuration page.

8. You will probably have a bridge named "br1" already configured (default). DELETE it.

9. Again, use the ADD feature. From the first drop down menu, select PPPoE (the phonebook entry we created above). Leave the encapsulation default of LLC/SNAP. Now click ADD.

10. On left hand selection menu, click SAVE ALL. (You may want to postpone this step for later, when you are sure you want this new configuration to remain permanent. The config changes are applied even if you don't perform this, they are just not saved across a restart).
    

This is it. If you followed everything carefully, you should now have full support for bridging PPPoE into PPPoA, over 8/48 (or, in lower tech jargon, your setup now supports PPPoE into Bezeq). 

Configure your PPPoE client (software or appliance) with your ISP credentials (full user - as in "tooki@IKzahav",  and password).

That's all! PPPoE should now be working.

As mentioned, now that VC 8/48 is allocated for PPPoE, it will not support PPTP (in other words, your previously configured PPTP client will now fail to connect). The process we went through is easily reversible:

• If you skipped the "SAVE ALL" in step 10 - all you have to do is power cycle your modem and the previous configuration will be booted into.
• Otherwise, you will need to go in the reverse order: delete the new bridge allocation you have just created, then delete it also from the phonebook, then create a phonebook entry for RELAY_PPP1 (8/48, PPTP), and then add PPTP gatewaying on RELAY_PPP1, with encap type VCMUX. Don't forget to SAVE ALL when all is done.

Good luck!