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PPPoA (PPP over ATM):
ADSL access via Point-to-Point Protocol (aka Dial-Up Networking). The "FastAccess ADSL" icon is located in the Dial-Up Networking folder. The user authenticates with userid and password, then connects. This is similar to dialup except no actual dialing takes place. Only available with the PCI or USB modems (or various unsupported alternative modems and routers).
PPPoE (PPP over Ethernet):
Another dial-up type connection method. PPPoE client software is from NTS (or various unsupported alternatives). The icon is typically located in a NTS EnterNet 300 folder. (As of EnterNet 1.34, integration with DUN is also possible.) Username, password and then connect as with PPPoA. Note that an additional layer of software is involved here.
Bridged/DHCP (RFC 1483):
Uses a standard DHCP network client which is native to every OS. DHCP should automatically negotiate an IP 'lease' on bootup. No special icons in any folders, no dialup type operations, no username and/or password required to connect, and no specialized software is required. This was the original type of service, but has been phased out in favor of PPPoE/A as of late spring/early summer 2000. This most closely resembles true 'always on'.
All new installations are now PPP. This can be either PPPoE (PPP over Ethernet) or PPPoA (PPP over ATM), two similar yet different protocols. Both use a mechanism similar to a dialup style connection: username and password are required. The server passes a (dynamic) IP address, netmask and other networking details back to the client once authentication has been successful.
The main difference is that with PPPoA, most of the work is done at the hardware level. So a modem that supports PPPoA is required. The Efficient 3060 and 4060 modems both support PPPoA (the Alcatel 1000/STH does not). The appropriate driver then needs to be loaded. The default connection method is via Windows DUN. A separate client ala NTS EnterNet is not required. DSL runs over ATM from the DSLAM to the modem no matter what modem we use. So this would seem to be the 'cleanest' solution for PPP customers.
PPPoE works via the 1483 Bridged driver, and requires client software to manage the session. This means that PPPoE is the only choice for Alcatel 1000/STH modem owners, and also IFITL customers. In fact, PPPoE will work with any of the four modems being offered. The officially supported PPPoE client is NTS's EnterNet, though there are various alternatives. All of which are unsupported, by the way.
PPPoE, by requiring client software, also means there is more overhead due to the additional ethernet layer. And consequently more system resources are used to maintain the connection. This may not be significant depending on your hardware and horsepower.
IFITL users do not need to worry about the modem drivers, since they don't use a modem at all. But still they need the PPPoE client (NTS) software in order to connect.
One of the drawbacks of the current PPP implementations is occasional disconnects. Apparently, the protocols are sensitive to any hiccup in the connection. One consequence here is that your IP address will change each time the connection is re-established. This is not just a BellSouth problem, but seems to be an industry wide issue with PPPoX implementations.
So why PPP? Aren't we trying to get away from dialup type connections?
Well, the answer from any ISP on this is that PPP simplifies a number of things on their end. They can essentially use their same infrastructure as their already well established, and much larger, dialup base. Simpler, means easier, means less costly. In any case, it is here to stay.
DHCP/Bridged service was the original FastAccess ADSL service. This is no longer being offered, as all new installs are now PPPoX.
DHCP (Dynamic Host Configuration Protocol) is a time-tested networking protocol for assigning IP addresses. It allows clients on a TCP/IP network to request and be assigned IP addresses dynamically from a centrally located server, and also to discover other necessary information about the network to which they are connected.
The DHCP server has a fixed pool of IPs, and assigns these when it receives a valid request. In our case, we are assigned 'sticky' IPs. Although these are dynamic (ie, not static), they tend to remain the same for long periods of time -- many months in some cases. The IP is 'leased' from the server's pool of available addresses, and eventually this lease must be renewed, or it will 'expire'.
The client's OS automatically requests a renewal after a predetermined period of time, and the server usually automatically complies. BellSouth.net is using a twelve hour lease. The server also provides other information to the client, such as nameservers, gateway, netmask, and broadcast address. All these are necessary in order to function on any TCP/IP network. The server also sets the maximum, allowed lease period. All this is handled fairly transparently and quietly by most operating systems. The initial request is broadcast during boot and special drivers are required.
The DHCP servers typically have names such as:
This one happens to also double as the local FastAccess primary nameserver. There would also seem to be a secondary, backup server: 'sun01sdf.sdf.BellSouth.net'. Some cities may still be using names such as ns.rdu.BellSouth.net. These seem to also do double duty as nameserver and DHCP server.
How do they know who we are? There has to be method of authenticating the user as a valid customer.
We are recognized by the 'MAC' addresses of our network adaptor. This is a unique hardware address (looks something like: 00 50 04 A8 77 11) that is recorded in a BellSouth database. The 'adaptor' may either be the Network Card as is the case of the Alcatel external, ethernet modems, or in the case of the Efficient Networks USB and PCI modems, the modem itself.
If you buy your own modem, or router, this will likely have its own, unique MAC address. Which means that anytime the network device is changed, BellSouth will need to know about it, or you won't be able to connect. This can be done by calling the FastAccess HelpDesk so they can register your new MAC address.
A recent round of upgrades included a conversion from Cisco to Redback 'termination' routers. And implemented a Redback feature known as 'Secure ARP'. Secure ARP has eliminated the ARP and IP broadcasts that used to be all too common. Nice improvement. It has also taken away the ability to assign ourselves static IPs when the DHCP server was down.
· PPPoE/A are fairly recent protocols. While it is increasingly popular with large ISPs like BellSouth, these are considered less reliable than former DHCP/Bridged set up by many. Occasional disconnects are the biggest complaint. This seems to be the nature of the beast.
· All the Efficient Networks modems supplied by BellSouth have built in diagnostics. Apparently true of the 3Com PCI as well. The Alcatel 1000/SpeedTouch ethernet modems have none unfortunately, and probably is one reason BSIS is reluctant to use these. (Alcatel USB???)
· If you are on Bridged/DHCP service, and you change your Network Card that is connected to the modem, you will have to re-register the new MAC address with tech support, or you won't be able to connect. They can walk you through this. Also true if you are using a PCI or USB modem and change to a different modem. PPPoX does NOT require MAC address registration. It is not used.
· For an alternative OS (Linux, *BSD, OS/2, BeOS, Solaris), your only real hope is the ethernet Alcatel. This connects via ethernet to a NIC, and will work with any OS. Another option is to buy your own modem or router outright. Just make sure it is compatible with BellSouth's DMT (Alcatel compatible) based DSL service. There are other possibilities, notably CAP based service that will not work! Be aware that while there are a number of modems, routers, etc that work just fine with BellSouth, the only ones actually supported are those as provided by BSIS.
· BellSouth does supply the Cayman 3220H router for Business ADSL. By all accounts, this is a good quality combo modem/router. Cost from BellSouth is about $300 (?). Works with PPPoA and Bridged mode, and is NAT ready.
· FastAccess ADSL is 'full rate' ADSL. BellSouth is not offering G.Lite at this time. Also, it is 'non-interleaved' or 'Fast' DMT. This is good for ping times.
One way to simplify the modem/driver/client mess, is to purchase a router. There are any number of models available. Some come with an integrated modem, and all handle the common protocols (DHCP, PPPoX). This takes all the burden off of your computer, since the router 'does it all'. Unfortunately, BSIS does not officially support any routers at this time. (The exception being the Cayman 3220 that is supported under the business plan.)