参数资料
| 型号： | KSZ8995FQI |
| 厂商： | Micrel Inc |
| 文件页数： | 22/89页 |
| 文件大小： | 0K |
| 描述： | IC SWITCH 10/100 5PORT 128-PQFP |
| 标准包装： | 66 |
| 系列： | * |
| 产品目录页面： | 1081 (CN2011-ZH PDF) |
| 配用： | 576-3872-ND - BOARD EVALUATION FOR KSZ8995FQ |
| 其它名称： | 576-3300 |
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Micrel, Inc.
KS8995MA/FQ
October 2011
29
M9999-102611-3.0
Functional Overview: Switch Core
Address Look-Up
The internal look-up table stores MAC addresses and their associated information. It contains a 1K unicast address table
plus switching information. The KS8995MA/FQ is guaranteed to learn 1K addresses and distinguishes itself from a hash-
based look-up table, 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 updates its table with a new entry if the following conditions are met:
The received packet’s source address (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 inserts the qualified SA into the table, along with the port number and time stamp. If the table is full,
the last entry of the table is deleted first to make room for the new entry.
Migration
The internal look-up engine also monitors whether a station is moved. If this occurs, it updates 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 the 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 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 + 75 seconds. This feature can be enabled or disabled through Register 3 or by external
pull-up or pull-down resistors on LED[5][2]. See “Register 3” section.
Forwarding
The KS8995MA/FQ will forward packets using an algorithm that is depicted in the following flowcharts. Figure 6 shows
stage one of the forwarding algorithm where the search engine looks up the VLAN ID, static table, and dynamic table for
the destination address, and comes up with “port to forward 1” (PTF1). PTF1 is then further modified by the spanning tree,
IGMP snooping, port mirroring, and port VLAN processes to come up with “port to forward 2” (PTF2), as shown in Figure
7. This is where the packet will be sent.
KS8995MA/FQ 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 KS8995MA/FQ will intercept these packets and perform 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 KS8995MA/FQ features a 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 KS8995MA/FQ
has a 64kB internal frame buffer. This resource is shared between all five ports. The buffer sharing mode can be
programmed through Register 2. See “Register 2.” In one mode, ports are allowed to use any free buffers in the buffer
pool. In the second mode, each port is only allowed to use 1/5 of the total buffer pool. There are a total of 512 buffers
available. Each buffer is sized at 128B.
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| KSZ8995M | 功能描述:以太网 IC 5 Port 10/100 Switch with PHY and Frame Buffers (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 |
| KSZ8995MA | 功能描述:以太网 IC 5 Port 10/100 Switch with PHY and Frame Buffers (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 |
| KSZ8995MA4 | 功能描述:IC SWITCH 5-PORT 10/100 128PQFP RoHS:是 类别:集成电路 (IC) >> 专用 IC 系列:* 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:调帧器 应用:数据传输 安装类型:表面贴装 封装/外壳:400-BBGA 供应商设备封装:400-PBGA（27x27） 包装:散装 |
| KSZ8995MAB3 | 功能描述:IC SWITCH 5-PORT 10/100 128PQFP RoHS:是 类别:集成电路 (IC) >> 专用 IC 系列:* 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:调帧器 应用:数据传输 安装类型:表面贴装 封装/外壳:400-BBGA 供应商设备封装:400-PBGA（27x27） 包装:散装 |
| KSZ8995MA-EVAL | 功能描述:以太网开发工具 KSZ8995MA 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: |
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