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Why doesn't Windows support two or more simultaneous PPPoE connections?
Is it because they work at layer 7 and Windows can't have more than one gateway?
What's that reason? Any idea?

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seriously, the network is getting cheaper and cheaper now. there is no point to work further on PPPoE, just image how it is possible handle 10k 1G subscriber with PPPoE, which requires an service providing endpoint. It is useful only in area which network is expensive and slow speed, which actually out of MS major marker. PS: they target the software at profit, which people need 2 PPPoE are just not worth their efforts. –  Antony Lee Sep 12 '13 at 14:43
    
Windows most definitely supports multiple gateways, what it does not support is multiple disjointed networks via default gateways. But it can still do it fine, you just need to manually create the entries using the route command. –  Scott Chamberlain Sep 13 '13 at 15:54
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2 Answers

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+25

The Point-to-point protocol is defined as a connection between two points. Your computer is one point and the remote connection is the other point. PPP operates in the data link layer 2 of the OSI model of computer networking.

There exists a flavor of it called Multilink PPP (RFC 1990), where the remote point is a combination of links consolidated into one point. This is even supported by Windows and called PPP Multilink Protocol. However, it needs multiple modems or a multiple-link router, together with a driver that can handle multiple connections.

These multiple connections must all be to the same destination, and packets are serialized over all the connections. This means that for the case of one-packet-message and one-packet-answer, only one connection is ever used. Only a stream of messages will use more than one connection.

The answer therefore to your question is : two PPPOE connections can connect at same time in Windows. One only needs the right hardware and the right driver. However, transfer speed can only improve for a stream of messages, such as for file transfers, and for the right hardware (for example two modems).

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Multilink PPP has nothing to do with this, and multiple simultaneous PPPoE sessions don't require special hardware. –  Spiff Sep 10 '13 at 17:27
    
@Spiff: Yes they do need hardware : multiple modems or the right router. As written above, nothing in Windows negates having two connections to two different locations. Multilink PPP is a PPP variant that enables using multiple connections to improve the bandwidth of one point-to-point connection, so is surely of interest. –  harrymc Sep 10 '13 at 18:19
    
No, you don't need special hardware. Any device that passes PPPoE (without necessarily being a PPPoE endpoint itself) automatically supports multiple PPPoE sessions. So if he already has a DSL modem that lets Windows make one PPPoE session, he already has all the hardware he needs to make 2^16 PPPoE sessions. –  Spiff Sep 10 '13 at 22:51
    
@Spiff: This means that either the poster's problem is imaginary or that you haven't understood what it was. –  harrymc Sep 12 '13 at 5:31
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The PPPoE protocol is perfectly capable of one machine handling multiple simultaneous PPPoE connections, even over a single standard Ethernet interface. Part of the 8-byte PPPoE header is a session ID that is used to differentiate between separate sessions.

If Windows' built-in PPPoE client doesn't support more than one connection at a time, then the team at Microsoft responsible for that code must have chosen to do it that way for their own reasons. Maybe they figured so few people would ever need more than one PPPoE session at a time, that it wasn't worth doing the code architecture and UI design and SQA effort to support it.

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Apart from the "8-byte" this answer contains nothing new. Microsoft surely would not include such a feature in a generic driver, so what does this add to my answer that says one needs the right driver? –  harrymc Sep 10 '13 at 18:13
    
@harrymc Perhaps you're using the term "driver" differently from me. To me, a "driver" is a hardware device driver. On a PC, the only hardware specifically involved in PPPoE is the Ethernet NIC, so the Ethernet NIC driver is the only driver involved. And since PPPoE traffic just looks like any other Ethernet traffic to the Ethernet NIC, the Ethernet NIC driver doesn't need to be special. I wouldn't call the software that implements PPPoE a "driver". It might be a kernel module or some other piece of operating system software, but I wouldn't call it a driver. –  Spiff Sep 10 '13 at 22:55
    
@harrymc Also, I don't see why Microsoft wouldn't put support for multiple simultaneous PPPoE sessions into Windows 7's default PPPoE software. In Mac OS X, I can easily create several separate PPPoE virtual interfaces on one Ethernet and have them connect simultaneously to separate PPPoE services at my ISP, all passing through my single no-frills DSL modem that I've had since 1999. –  Spiff Sep 10 '13 at 23:00
    
Perhaps your problem is, as wikipedia says : "the term ‘PPPoE’ is used sometimes confusingly to refer to either or both of two things: (i) a modem-to-router protocol; (ii) on the DSL side of things, a part of a protocol stack". In both cases, hardware plays a part, and requires a driver that knows the right protocol. Multiple PPPoE connections are not interesting at all if they cannot be used to improve bandwidth for a single target, which my answer did try to treat. –  harrymc Sep 11 '13 at 5:53
    
As a side-remark, I suggest that you avoid down-voting other answers, even if you are absolutely sure that yours is the only correct one. It is better to let the poster and the community decide on its merits. –  harrymc Sep 11 '13 at 5:55
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