参数资料
| 型号： | KSZ8999 |
| 厂商： | Micrel Inc |
| 文件页数： | 15/52页 |
| 文件大小： | 0K |
| 描述： | IC SWITCH 10/100 9PORT 208PQFP |
| 标准包装： | 24 |
| 系列： | * |
| 类型： | * |
| 应用： | * |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 208-MQFP，208-PQFP |
| 供应商设备封装： | 208-PQFP（28x28） |
| 包装： | 托盘 |
| 产品目录页面： | 1081 (CN2011-ZH PDF) |
| 配用： | 576-1644-ND - BOARD EVALUATION FOR KSZ8999 |
| 其它名称： | 576-1044 |
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KS8999
Micrel
KS8999
22
January 2005
Functional Overview: Switch Core
Address Look-Up
The internal look-up table stores MAC addresses and their associated information. It contains 1K full CAM with 48-bit address
plus switching information. The KS8999 is guaranteed to learn 1K addresses and distinguishes itself from hash-based look-
up tables which, depending on the operating environment and probabilities, may not guarantee the absolute number of
addresses it can learn.
Learning
The internal look-up engine will update its table with a new entry if the following conditions are met:
The received packet’s SA does not exist in the look-up table.
The received packet is good; the packet has no receiving errors, and is of legal length.
The look-up engine will insert the qualified SA into the table, along with the port number, time stamp. If the table is full, the last
entry of the table will be deleted first to make room for the new entry.
Migration
The internal look-up engine also monitors whether a station is moved. If it happens, it will update the table accordingly.
Migration happens when the following conditions are met:
The received packet’s SA is in the table but the associated source port information is different.
The received packet is good; the packet has no receiving errors, and is of legal length.
The look-up engine will update the existing record in the table with the new source port information.
Aging
The look-up engine will update time stamp information of a record whenever the corresponding SA appears. The time stamp
is used in the aging process. If a record is not updated for a period of time, the look-up engine will then remove the record from
the table. The look-up engine constantly performs the aging process and will continuously remove aging records. The aging
period is 300 seconds. This feature can be enabled or disabled by external pull-up or pull-down resistors.
Forwarding
The KS8999 will forward packets as follows:
If the DA look-up results is a “match”, the KS8999 will use the destination port information to determine where the
packet goes.
If the DA look-up result is a “miss”, the KS8999 will forward the packet to all other ports except the port that received
the packet.
All the multicast and broadcast packets will be forwarded to all other ports except the source port.
The KS8999 will not forward the following packets:
Error packets. These include framing errors, FCS errors, alignment errors, and illegal size packet errors.
802.3x pause frames. The KS8999 will intercept these packets and do the appropriate actions.
“Local” packets. Based on destination address (DA) look-up. If the destination port from the look-up table matches
the port where the packet was from, the packet is defined as “local”.
Switching Engine
The KS8999 has a very high performance switching engine to move data to and from the MAC’s, packet buffers. It operates
in store and forward mode, while the efficient switching mechanism reduces overall latency.
The KS8999 has an internal buffer for frames that is 32Kx32 (128KB). This resource could be shared between the nine ports
and is programmed at system reset time by using the unmanaged program mode (I/O strapping).
Each buffer is sized at 128B and therefore there are a total of 1024 buffers available. Two different modes are available for
buffer allocation. One mode equally allocates the buffers to all the ports (113 buffers per port). The other mode adaptively
allocates buffers up to 512 to a single port based on loading. Selection is achieved by using LED[7][1] in the unmanaged
programming description.
MAC Operation
The KS8999 strictly abides by IEEE 802.3 standard to maximize compatibility.
Inter Packet Gap (IPG)
If a frame is successfully transmitted, the 96 bit time IPG is measured between the two consecutive MTXEN. If the current
packet is experiencing collision, the 96 bit time IPG is measured from MCRS and the next MTXEN.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| KSZ8999-EVAL | 功能描述:以太网开发工具 KSZ8999 Evaluation Board RoHS:否 制造商:Micrel 产品:Evaluation Boards 类型:Ethernet Transceivers 工具用于评估:KSZ8873RLL 接口类型:RMII 工作电源电压: |
| KSZ8999-EVAL | 制造商:Micrel Inc 功能描述:BOARD EVALUATION FOR KSZ8999 |
| KSZ8999I | 功能描述:以太网 IC 8 Port 10/100 Switch plus MII with PHY and Frame Buffers I-temp (Lead Free) RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
| KSZ9021GN | 功能描述:以太网 IC Gigabit Ethernet Transceiver with GMII/MII, Lead Free RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
| KSZ9021GN TR | 功能描述:以太网 IC Gigabit Ethernet Transceiver with GMII/MII RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
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