Siemens CL-010-I User Manual

Chapter 7: Glossary 

configured and mapped to a private workstation address when accesses are made through 

the gateway to a public network.   
For example, the ADSL Router is assigned with the public IP address of 168.111.2.1. With 

NAT enabled, it creates a Virtual LAN. Each PC on the Virtual LAN is assigned with a private 
IP address with default value of 192.168.1.2 to 192.168.2.254. These PCs are not 

accessible by the outside world but they can communicate with the outside world through 
the public IP 168.111.2.1. 

Private IP addresses are also LAN IP addresses, but are considered “illegal” IP addresses to 
the Internet. They are private to an enterprise while still permitting full network layer 

connectivity between all hosts inside an enterprise as well as all public hosts of different 
enterprises. 
The ADSL Router uses private IP addresses by assigning them to the LAN that cannot be 
directly accessed by the Internet or remote server. To access the Internet, private network 

should have an agent to translate the private IP address to public IP address. 

Public IP addresses are LAN IP addresses that can be considered “legal” for the Internet, 

because they can be recognized and accessed by any device on the other side of the DSL 
connection. In most cases they are allocated by your ISP.   
If you are given a range of fixed IP addresses, then one can be assigned to the router and 
the others to network devices on the LAN, such as computer workstations, ftp servers, and 

web servers. 

A PVC is a logical point-to-point circuit between customer sites. PVCs are low-delay circuits 

because routing decisions do not need to be made along the way. Permanent means that 
the circuit is preprogrammed by the carrier as a path through the network. It does not 

need to be set up or turned down for each session. 

RIP is a routing protocol that uses the distance-vector routing algorithms to calculate 

least-hops routes to a destination. It is used on the Internet and is common in the NetWare 
environment. It exchanges routing information with other routers. It includes V1, V2 and 

V1&V2, which controls the sending and receiving of RIP packets over Ethernet. 

UDP is a connectionless transport service that dispenses with the reliability services 

provided by TCP. UDP gives applications a direct interface with IP and the ability to address 
a particular application process running on a host via a port number without setting up a 

connection session. 

You can designate virtual servers, e.g., a FTP, web, telnet or mail server, on your local 

network and make them accessible to the outside world. A virtual server means that it is 
not a dedicated server -- that is, the entire computer is not dedicated to running on the 

public network but in the private network. 

A VPI is a 8-bit field while VCI is a 16-bit field in the ATM cell header. A VPI identifies a link 

formed by a virtual path and a VCI identifies a channel within a virtual path. In this way,