1. CCUCOMM 網路前瞻實驗室 Yi-Chi Cheng 鄭伊騏
期中報告
CCUCOMM 網路前瞻實驗室 Yi-Chi Cheng 鄭伊騏
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2. Outline
Introduction
HTB
Future Work
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3. Hierarchical Token Bucket (1/2)
HTB is one of the packet scheduler. It is currently included in stock Linux kernels from
Control the use of the outbound bandwidth on a given link.
Using one physical link to simulate several slower links.
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4. Hierarchical Token Bucket (2/2)
Send different kinds of traffic on different simulated links.
Ensures that the amount of service provided to each class is at least the minimum of the amount it requests and the amount assigned to it.
Allow “lower” priority queue to borrow the bandwidth form the higher priority queue when it’s idle.
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5. Traffic control for Linux (1/3)
Consist of Queuing disciplines (Qdisc) , classes and filters.
filter
queuing discipline
class
packet
filter
class
queuing discipline
filter
queuing discipline function
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6. Traffic control for Linux (2/3)
Filter
依據封包的來源不同(IP或port)，來決定其Class
Class
依據Application及Data type不同，分送到不同的Queuing Discipline
Queuing Discipline
不同的Qdisc會有不同的排程方式，如：FIFO
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7. Traffic control for Linux (3/3)
Classful qdisc : CBQ, HTB
Classless qdisc : FIFO, TBF, RED
Application Aware:
固定port
Dynamic port:依據signaling內容來處理
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8. Introduction AR: Assure rate CR: ceil rate Mode:
Red：R>CR [HTB_CANT_SEND]
Yellow：R ≦ CR and R > AR [HTB_MAY_BORROW]
Green：otherwise [HTB_CAN_SEND]
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14. Future Work
Measure the performance of the VoIP transmission with HTB and without HTB.
Find out why HTB can’t run so precisely?
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