Vivint SR1410, Инструкция по установке и эксплуатации, Страница: 21 / 38

SR1410 Installation and User Guide Page 21
SR1410 Installation & User Guide Ver. 0.01
The Hierarchical Token Bucket[HTB] creates a hierarchy of software queues called qdiscs which
represent the flow of traffic on a network interface. A parent (base) qdisc can have multiple child qdiscs
which in turn can be parents to other qdiscs. A leaf qdisc is the one which has no children.
The HTB is a classfull qdisc which means that traffic flowing through the interface can be classified into
flows. The classification can be performed using various filters assigned to the qdisc. The parameter
"rate" in the above command specifies the base or guaranteed bit rate of the qdisc corresponding to the
class. The parameter burst corresponds to the amount of data in bytes that will be processed at a time for
that qdisc. For an ingress qdisc it represents the bytes send up to the network stack for processing. For an
egress qdisc it represents the amount of data sent to the hardware for transmitting out. The parameter
"ceil" or ceiling represents the maximum bit rate for the qdisc. HTB qdiscs have the capability to borrow
bandwidth from peers which will be explained in the subsequent sections.
Example: tc class add dev eth0 parent 1:1 classid 1:10 htb rate 50mbit burst 1mbit ceil 60mbit
tc class add dev eth0 parent 1:1 classid 1:11 htb rate 20mbit burst 1mbit ceil 40mbit
The above commands create qdiscs of class labeled "1:10" and "1:11" for the qdisc "1:1". The parameter
"rate" represents the guaranteed or base bit rate for the qdiscs. The parameter "burst" is the amount of
data transmitted/received for the qdisc in a given time period. The parameter "ceil" is the maximum bit
rate for the qdisc. As mentioned before peer qdiscs can borrow bandwidth from each other if one of the
qdiscs is using less than base bandwidth or there is unused bandwidth available. Suppose qdisc 1:10 uses
50mbits but requires a total of 60mbps due to the bandwidth intensive nature of the application.. On the
other hand class 1:11 is using 10mbits out of the assigned 20mbits base bandwidth. In this case class
1:10 can borrow the additional 10mbps from 1:11 and use up its maximum assigned bandwidth of
60mbps.