AOL PPP Information
PPP Overview
Outside the AOL customer base, more than 99% of dial-up users connect to the Internet via PPP. Even though, AOL considers itself a leader in network services, it still rides in the wake of hardware trends set by the ISPs. AOL must adopt its service to synchronous PPP, the greatest common factor of ISDN connection methods. Without this connection facility, AOL will stand at a significant competitive disadvantage in Europe and Asia. Synchronous PPP is a connection method common to more than 90% of all ISDN cards and external TAs. Although most cards or external TAs will support either X.75, V.120 or V.110, these protocols are either slower, or more CPU intensive and thus less popular.
AOL PPP Model (for AOL networks)
Through an ISP, a user connecting via PPP goes through several connection stages: dial up, authentication, IP address allocation, and DNS assignment. AOL works within this standard but adds a number of extra stages. As with P3 dial-in, AOL uses a generic login and password at the hub. True authentication is differed to the application layer at Step 7. Then to prevent a user from skating off into the Internet, the dial-in hub filters the user’s traffic, and only permits communication with AOL TFEPs and Super Tunnels. In the future, the hubs may use T2TP to tunnel users to the TFEPs.
Once the hub has authenticated a user with a generic login and password, the user receives a DNS address. The client will use this first DNS address furnished by the network provider to look up the address of an AOL DNS server, a DNS that distributes users across multiple TFEP IP’s. With the URL of the secondary DNS, the client will request the address of a TFEP and make a TCP/IP connection.
Once connected to the TFEP, the client will also be given the address of a Super Tunnel to which it will connect for web and Internet access. The Super Tunnel provides proxied web access to those connecting with the AOL PPP client. A user cannot access the web tunnels without using the AOL PPP connection engine. If a Supertunnel is not available AOL will use its P3 protocol. The UDP layer encapsulates TCP/IP requests to the web. Ultimately an AOL client will have two connections to the AOL service, one to the TFEPs and another to a prescribed Super Tunnel.
12/14/99 2:54 PM
