Why do some DSL services use pppoe, which is like using both dialup and ethernet, whereas some DSL services seem to just use ethernet?
Doesn't this affect whether or not DSL connects automatically at startup?
I think SBC DSL uses pppoe.
It gives them more control.
It means you have to establish a pppoe session and, most likely, login.
They do. But there are some customers without it.
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Hi Richard,
You seem to have made an association that is not really there........;-) PPP is not JUST dialup, it is a protocol for authenticating WHO the user is at the other end of a connection, and it sets that connection up to carry IP type traffic. The connection can be any one of Dial-up, DSL, Cable or whatever form of WAN connection you are using. You can even use PPP over a Frame-Relay link or over an ISDN service if you wish, and you can even 'stack" these to create a larger "pipe" using what is known as "Multi-Link PPP".
Some things to think about - 1. PPP stands for "Point-to-Point" Protocol. As such, it is only a SESSION management protocol and it MUST be used over some form of carrier service, be it Dial-up, DSl, Cable, Etc... It replaced what started life as SLIP (Serial Line Internet Protocol), however SLIP had limitations that do not exist in PPP. 2. PPP over Dial-up Modem is the simplest form of PPP service commonly used today. 3. PPPoA (PPP over ATM) is a PPP link over a DSL service. DSL uses ATM technology (Asynchronous Transfer Mode) as its carrier service. 4. PPPoE is an PPP session over an Ethernet Service, however to do this you first need an Ethernet service in place. You could use PPP on an Ethernet link if you wish, however a more common form is to configure a DSL service to provide Ethernet type connectivity, and then use PPP for Authentication. The 2 most common forms of PPPoE are PPPoE over a Cable environment, or PPPoEoA, which is PPPoE over DSL 5. In addition, it is possible to configure a DSL service to deliver pure Ethernet style connectivity, without PPP, however then the ISP then has to work out how the end user is to be Authenticated and managed, and this can pose some problems for them. 6. Lastly, just to be really confusing, in some places a provider may choose to deliver a DSL connection using ISDN services, rather than ATM technology, however these are limited to 128Kbps and are fairly rare and specific to longer run cable distances.
A key thing to remember is that some of the current terminology has been adapted from pre-existing installations, and often you find some DSL service provisioned using PPPoE instead of PPPoA, but the end result is very similar.
Nope, it has nothing to do with it at all. What is important though is to understand the ISO Protocol Layers being used, and to understand where things fit in. A very rough analogy is - 1. ISO layer 1 is the copper cable that goes into your house. it is the PHYSICAL MEDIUM used to deliver the service. 2. ISO layer 2 is the FRAMING or signalling on that cable (layer 1), and it could be either V90 Dial-up Modem, Cable, or DSL (as examples). 3. ISO layer 3 is the PPP session itself. This is the layer that provides a method to authenticate WHO is at the end of the cable, and once successful it provides the base level TCP/IP transport layer that is required to get internet data between YOUR place and your ISP.. 4. ISO layers 4 - 7 are the traffic handling layers that the software on your PC uses.
It is also critical to understand that for any layer to be able to work, you MUST have the layer immediately below it in place first.
This is a very quick intro into all this but I hope it helps.
Cheers...........pk.
Actually it's just a protocol for encapsulating packets. Some of those packets might be for authentication but that's entirely optional.
Personally I find the use of PPP over ethernet to be just plain stupid. Ethernet already has encasulation and doesn't need more overhead stacked on top of it.
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'at's what radius is all about (g).
login _is_ ppp. running it over ethernet is just a twist.
And if they make _any_ changes (even circuit change) to their account they will have to go to pppoe.
No, it isn't.
Most all use PPPoE or similar. When you see the "just use ethernet" they very most likely have given you a modem router and the router is handing you an IP via DHCP.
They use PPPoE, which is not dialup. It uses PPP for authentication and to encapsulate the traffic.
I can't say why some telcos use PPPoE - the reason probably varies between telcos. One advantage is that PPPoE gives them more flexibility.
In an ethernet circuit, the gateway router has to be on the same LAN segment. Either the ISP has to provide each user with a private LAN segment, using 4 IP addresses, or it shares a LAN segment with several users and they see each other's broadcasts, ARP requests, etc. Use of PPP avoids this limitation, since it allows multiple PPP links, each with a private segment, sharing use of a gateway that forwards packets to the internet.
My DSL (using PPPoE) connects automatically at startup. Where is the problem?
Lets them stack more customers per IP.
Interestingly DSL here in Germany is provided by the T-Com (the has been monopolist) but there are several Internet Providers on top of this.
So I can choos my provider by just changing pppoe login. And even more interestingly it is even possible to connect to more than one provider over ONE DSL line at the same time!
Wolfgang
Mine doesn't.
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