Chapter 17 Bandwidth MGMT

17.1.8 Bandwidth Borrowing

Bandwidth borrowing allows a sub-class to borrow unused bandwidth from its parent class, whereas maximize bandwidth usage allows any bandwidth class to borrow any unused or unbudgeted bandwidth on the whole interface.

Enable bandwidth borrowing on a sub-class to allow the sub-class to use the parent class’s unused bandwidth. The parent class’s unused bandwidth is given to the highest priority subclass first (see Section 17.1.8.1 on page 209).

The total of the bandwidth allotments for sub-classes cannot exceed the bandwidth allotment of the parent class. The ZyXEL Device uses the scheduler to divide the parent class’s unused bandwidth among the sub-classes that have bandwidth borrowing enabled.

17.1.8.1 Bandwidth Borrowing Example

Here is an example of bandwidth management with classes configured for bandwidth borrowing. The classes are set up based on departments and individuals within certain departments.

Table 96 Bandwidth Borrowing Example

BANDWIDTH CLASSES AND BANDWIDTH BORROWING SETTINGS

Root Class:

Administration: Borrowing Enabled

 

 

 

Sales: Borrowing Disabled

 

 

 

Marketing: Borrowing Enabled

 

 

 

Research: Borrowing Enabled

 

 

•The Sales class cannot borrow unused bandwidth from the Root class because the Sales class has bandwidth borrowing disabled.

17.1.8.2Maximize Bandwidth Usage With Bandwidth Borrowing

If you configure both maximize bandwidth usage (on the interface) and bandwidth borrowing (on individual sub-classes), the ZyXEL Device functions as follows.

1The ZyXEL Device sends traffic according to each bandwidth class’s bandwidth budget.

2The ZyXEL Device assigns a parent class’s unused bandwidth to its sub-classes that have more traffic than their budgets and have bandwidth borrowing enabled. The ZyXEL Device gives priority to sub-classes of higher priority and treats classes of the same priority equally.

3The ZyXEL Device assigns any remaining unused or unbudgeted bandwidth on the interface to any class that requires it. The ZyXEL Device gives priority to classes of higher priority and treats classes of the same level equally.

4If the bandwidth requirements of all of the traffic classes are met and there is still some unbudgeted bandwidth, the ZyXEL Device assigns it to traffic that does not match any of the classes.

 

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P-2302HWUDL-P1 Series User’s Guide