<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Xinetd</i>
<br />OK. It is true, all international outgoing traffic is tracked by a RADIUS server ...
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PLUR
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Sort of. Let me give you the low down.
There is only one ADSL infrustructure provider in S.A., yup you guessed it SAIX. Every ISP (except MWeb, more about this later) is simply reselling ADSL. Most of the smaller ISP's don't even have their own radius servers, they let SAIX handle it for them. So the ISP will pay X rands per month for a username/password to SAIX and the sell that username/password to us for X + markup rands per month. That simple. MWeb has installed their own BRAS so that they can use their own bandwidth for their ADSL customers.
Once you have an ADSL connection at home you can use any ISP you wish. You can even be connected to 4 different ISP's at once
. Once your username/password is authenticated the traffic counting starts. Every packet that goes up or down your connection is totalled. There is no descrimination between International and local destinations.
Like I said earlier, most ISP's let SAIX handle the traffic management for them, your ISP is one of these if you log into SAIX to check your monthly usage (http://userstats.adsl.saix.net/). The larger ISP's have their own radius servers and maintain their own traffic databases, e.g. Telkom Internet.
These larger ISP's have their own radius servers which do authentication for their user base, so SAIX simply forwards all logon requests to their radius servers. They get a radius start record from SAIX when you logon and a stop record when you logoff. The stop record contains the number of Rx/Tx octets (bandwidth) used for your session. These values are added to your running total. Usually on a daily basis your bandwidth total is checked and if it has exceeded 3GB then your are "capped".
As the radius protocol uses UDP and because there are always problems somewhere the stop records do not always reach the radius servers. In this case some ISP's will then just ignore that session and you score the used bandwidth free. Other ISP's go one step futher and fall back to the last alive record (an alive record is sent every 30 minutes you are logged on) and treat that as a stop record. So if this happens you can score a maximum of the last 30 minutes bandwidth free. If you can determine when this will happen so that you benefit, please let me know
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Once you are "capped" you will notice that your IP adressess 3rd octet is much smaller than normal, i.e. 165.165.x. Traffic with capped IP addressess are routed Internationaly over a different PVC that has very little bandwidth allocated to it while the rest of the ADSL traffic goes over the "larger" PVC. Simple as that.
The only way you can effectively bypass the capping is to route your International traffic via a non-ADSL IP address, like a proxy. Naturally SAIX does not allow connections to cache.saix.net from the 165.165/16 address block so if you can find a badly configured local proxy my advice is to keep it to yourself and reap the benefits.
The next best thing is to have more than one login. You can either use one login at a time until the cap is reached or have multiple connections setup and do policy based routing over these links (very easy with Linux). For example, the latter setup with 4 logins. Policy based routing splitting http,ftp,email,p2p over different links. So when the p2p traffic gets capped it does not affect surfing, email, etc.. If p2p is important to you then you can simply move that particular type of traffic to one of the other less used links. Make sense?
I've rattled on long enough, any questions, just post them to the forum.
Apple // Forever.
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