ZyXEL Communications 650HW Manual Do Utilizador

                                                                                     Prestige 650HW ADSL Router User’s Guide 

Internet Access 

 

3-19 

DNS Server 
Address 
Assignment 
 

Primary DNS server 
Secondary DNS server  
Enter when using RFC 1483 Encapsulation or a static 
IP address. 

 

ENET ENCAP 
Gateway 
 

IP Address 
Gateway IP Address  
Enter when using ENET ENCAP Encapsulation. 

 

Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate and 
“burstiness” or fluctuation of data transmission over an ATM network. This agreement helps eliminate 
congestion, which is important for transmission of real time data such as audio and video connections. 

Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may be lower 
(but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a maximum speed of 
832 Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed because it is dependent on 
the line speed. 

Sustained Cell Rate (SCR) is the mean cell rate of a bursty, on-off traffic source that can be sent at the peak 
rate, and a parameter for burst-type traffic.

 

 SCR may not be greater than the PCR; the system default is 0 

cells/sec.  

Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS is 
reached, cell rates fall below SCR until cell rate averages to the SCR again.  At this time, more cells (up to 
the MBS) can be sent at the PCR again.

  

The following figure illustrates the relationship between PCR, SCR and MBS.