Chapter 28 Bandwidth Management

Maximize Bandwidth Usage Effect

With maximize bandwidth usage enabled, after each server gets its configured rate, the rest of the available bandwidth is divided equally between the two. So server A gets its configured rate of 300 kbps and server B gets its configured rate of 200 kbps. Then the ZyWALL divides the remaining bandwidth (1000 - 500 =

500)equally between the two (500 / 2 = 250 kbps for each). The priority has no effect on how much of the unused bandwidth each server gets.

So server A gets its configured rate of 300 kbps plus 250 kbps for a total of 550 kbps. Server B gets its configured rate of 200 kbps plus 250 kbps for a total of 450 kbps.

Table 129 Maximize Bandwidth Usage Effect

POLICY

CONFIGURED RATE

MAX. B. U.

PRIORITY

ACTUAL RATE

A

300 kbps

Yes

1

550 kbps

 

 

 

 

 

B

200 kbps

Yes

2

450 kbps

 

 

 

 

 

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 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.

Table 130 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

 

 

 

 

 

Finding Out More

•See Section 7.5 on page 120 for an example of how to set up web surfing policies with bandwidth restrictions.

•See DSCP Marking and Per-Hop Behavior on page 299 for a description of DSCP marking.

28.1.3Bandwidth 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.

 

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ZyWALL USG 20/20W User’s Guide