Measurements are executed at the xDSL subnetwork of the telecommunication test network. Block diagram of the measuring arrangement and the so called "protocol stack" of the information transmission is shown on the following figure:
In the measuring arrangement we realize an Internet service between the INTERNET and the Internet user(s). In the first part of the exercise we will learn about the elements of the network, and then we will configure them. Then we will execute measurement in the ADSL and Ethernet layers of the network, and evaluate the results. At the end of the exercise we will deepen our obtained knowledge with error searching and improving.
This service is realized through the equipment of the Internet service provider (ISP) (DSLGW, DSLAM, subscriber cable network, modem).
Network of the users a local network with NAT. Distribution of traffic among the users is made by the VLAN switch in the DSLAM. For the quick operation of the switch users are organized to VLANs (virtual LAN) by the provider. The IP address-VLAN ID assignment, and the network address translation are made by the DSLGW.
Connection, dissociation and control of eligibility are made by the PPPoE server.
Internet traffic is forwarded from the provider to the user in the ADSL line section. A line section consists of a subscriber cable pair of tracks, and of a modem in both of the ends. We can simulate the subscriber pair of tracks in the measuring arrangement, together with the generated noises. The modems of the line section side (LTU) can be found in the DSLAM. There are further network elements in the box of the modem (NTU) from the users' side (router, several (100BASE-T, WLAN) interfaces).
In the measuring arrangement the terminal of the user is connected to the modem through WLAN (Wireless LAN) interface.
Theoratical summary: In general the related chapters of Tutorial!
Note: To perform this laboratory exercise it is not required to accomplish the partially ADSL-related TTMER6 before!