ZyXEL Communications ZyWALL 2 Plus - Manual (Page 356)

Chapter 19 Bandwidth Management
ZyWALL 2 Plus User’s Guide
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Refer to the product specifications in the appendix to see how many class levels you can
configure on your ZyWALL.
• The Administration class can borrow unused bandwidth from the Root class because the
Administration class has bandwidth borrowing enabled.
• The Sales class cannot borrow unused bandwidth from the Root class because the Sales
class has bandwidth borrowing disabled.
19.9 Maximize Bandwidth Usage With Bandwidth Borrowing
If you configure both maximize bandwidth usage (on the interface) and bandwidth borrowing
(on individual sub-classes), the ZyWALL functions as follows.
1 The ZyWALL sends traffic according to each bandwidth class’s bandwidth budget.
2 The ZyWALL assigns a parent class’s unused bandwidth to its sub-classes that have
more traffic than their budgets and have bandwidth borrowing enabled. The ZyWALL
gives priority to sub-classes of higher priority and treats classes of the same priority
equally.
3 The ZyWALL assigns any remaining unused or unbudgeted bandwidth on the interface
to any class that requires it. The ZyWALL gives priority to classes of higher priority and
treats classes of the same level equally.
4 If the bandwidth requirements of all of the traffic classes are met and there is still some
unbudgeted bandwidth, the ZyWALL assigns it to traffic that does not match any of the
classes.
19.10 Over Allotment of Bandwidth
It is possible to set the bandwidth management speed for an interface higher than the
interface’s actual transmission speed. Higher priority traffic gets to use up to its allocated
bandwidth, even if it takes up all of the interface’s available bandwidth. This could stop lower
priority traffic from being sent. The following is an example.
Table 106 Bandwidth Borrowing Example
BANDWIDTH CLASSES AND BANDWIDTH BORROWING SETTINGS
Root Class: Administration: Borrowing Enabled
Sales: Borrowing Disabled
Marketing: Borrowing Enabled
Research: Borrowing Enabled
Table 107 Over Allotment of Bandwidth Example
BANDWIDTH CLASSES, ALLOTMENTS PRIORITIES
Actual outgoing bandwidth available on the interface: 1000 kbps
Root Class: 1500 kbps (same
as Speed setting)
VoIP traffic (Service = SIP): 500 Kbps 7
NetMeeting traffic (Service = H.323): 500 kbps 7
FTP (Service = FTP): 500 Kbps 3