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Chapter 25 Bandwidth Management
ISG50 User’s Guide
401
Priority and Over Allotment of Bandwidth Effect
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 ISG50 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.
Finding Out More
•See Section 7.5 on page 116 for an example of how to set up web surfing policies with bandwidth
restrictions.
•See DSCP Marking and Per-Hop Behavior on page 291 for a description of DSCP marking.
25.1.3 Bandwidth Management Examples
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.
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.
Table 132 Priority and Over Allotment of Bandwidth Effect
POLICY CONFIGURED RATE MAX. B. U. PRIORITY ACTUAL RATE
A 1000 kbps Yes 1 999 kbps
B 1000 kbps Yes 2 1 kbps