參數(shù)資料
型號: MVTX2802AG
廠商: ZARLINK SEMICONDUCTOR INC
元件分類: 網(wǎng)絡(luò)接口
英文描述: Managed 4-Port 1000 Mbps Ethernet Switch
中文描述: DATACOM, LAN SWITCHING CIRCUIT, PBGA596
封裝: 40 X 40 MM, 2.33 MM HEIGHT, MS-034, HSBGA-596
文件頁數(shù): 27/154頁
文件大小: 1936K
代理商: MVTX2802AG
MVTX2802
Data Sheet
27
Zarlink Semiconductor Inc.
loss, and the first to be discarded will be high-drop. Of course, if this is insufficient to resolve the congestion,
eventually some low-drop frames are dropped as well.
Table 1 shows that different types of applications may be placed in different boxes in the traffic table. For
example, web search may fit into the category of high-loss, high-latency-tolerant traffic, whereas VoIP fits into
the category of low-loss, low-latency traffic.
7.2 Four QoS Configurations
There are four basic pieces to QoS scheduling in the MVTX2802AG: strict priority (SP), delay bound, weighted
fair queuing (WFQ), and best effort (BE). Using these four pieces, there are four different modes of operation,
as shown in Table 2.
The default configuration is six delay-bounded queues and two best-effort queues. The delay bounds per class are
0.16 ms for P7 and P6, 0.32 ms for P5, 0.64 ms for P4, 1.28 ms for P3, and 2.56 ms for P2. Best effort traffic is only
served when there is no delay-bounded traffic to be served. P1 has strict priority over P0.
We have a second configuration in which there are two strict priority queues, four delay bounded queues, and
two best effort queues. The delay bounds per class are 0.32 ms for P5, 0.64 ms for P4, 1.28 ms for P3, and
2.56 ms for P2. If the user is to choose this configuration, it is important that P7-P6 (SP) traffic be either
policed or implicitly bounded (e.g. if the incoming SP traffic is very light and predictably patterned). Strict priority
traffic, if not admission-controlled at a prior stage to the MVTX2802AG, can have an adverse effect on all other
classes’ performance. P7 and P6 are both SP classes, and P7 has strict priority over P6.
The third configuration contains two strict priority queues and six queues receiving a bandwidth partition via
WFQ. As in the second configuration, strict priority traffic needs to be carefully controlled.
In the fourth configuration, all queues are served using a WFQ service discipline.
7.3 Delay Bound
In the absence of a sophisticated QoS server and signaling protocol, the MVTX2802AG may not be assured of
the mix of incoming traffic ahead of time. To cope with this uncertainty, our delay assurance algorithm
dynamically adjusts its scheduling and dropping criteria, guided by the queue occupancies and the due dates of
their head-of-line (HOL) frames. As a result, we assure latency bounds for all admitted frames with high
confidence, even in the presence of system-wide congestion. Our algorithm identifies misbehaving classes and
intelligently discards frames at no detriment to well-behaved classes. Our algorithm also differentiates between
high-drop and low-drop traffic with a weighted random early drop (WRED) approach. Random early dropping
prevents congestion by randomly dropping a percentage of high-drop frames even before the chip’s buffers are
completely full, while still largely sparing low-drop frames. This allows high-drop frames to be discarded early,
as a sacrifice for future low-drop frames. Finally, the delay bound algorithm also achieves bandwidth partitioning
among classes.
P7
P6
P5
P4
P3
P2
P1
P0
Op1 (
default)
Delay Bound
BE
Op2
SP
Delay Bound
BE
Op3
SP
WFQ
Op4
WFQ
Table 2 - Four QoS configurations per port.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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MVTX2803A 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Unmanaged 8 port Gigabit Ethernet switch
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MVTX2803AG2 制造商:Microsemi Corporation 功能描述:
MVTX2804 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:8-Port 1000 Mbps Ethernet Distributed Switch