ZyXEL Communications 200 Series User Manual

Chapter 27 Application Patrol

ZyWALL USG 100/200 Series User’s Guide

Server A has a configured rate that equals the total amount of available bandwidth and a 
higher priority. You should regard extreme over allotment of traffic with different priorities 
(as shown here) as a configuration error. Even though the ZyWALL still attempts to let all 
traffic get through and not be lost, regardless of its priority, server B gets almost no bandwidth 
with this configuration.    

• See 

 for related information on these screens.

• See 

 for an example of how to set up web surfing policies with 

bandwidth restrictions.

Bandwidth management is very useful when applications are competing for limited 
bandwidth. For example, say you have a WAN zone interface connected to an ADSL device 
with a 8 Mbps downstream and 1 Mbps upstream ADSL connection. The following sections 
give some simplified examples of using application patrol policies to manage applications 
competing for that 1 Mbps of upstream bandwidth. 

Here is an overview of what the rules need to accomplish. See the following sections for more 
details.

• SIP traffic from VIP users must get through with the least possible delay regardless of if it 

is an outgoing call or an incoming call. The VIP users must be able to make and receive 
SIP calls no matter which interface they are connected to. 

• HTTP traffic needs to be given priority over FTP traffic.

• FTP traffic from the WAN to the DMZ must be limited so it does not interfere with SIP 

and HTTP traffic.

• FTP traffic from the LAN to the DMZ can use more bandwidth since the interfaces 

support up to 1 Gbps connections, but it must be the lowest priority and limited so it does 
not interfere with SIP and HTTP traffic.

Table 136   Priority and Over Allotment of Bandwidth Effect

A

1000 kbps

Yes

1

999 kbps

B

1000 kbps

Yes

2

1 kbps