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| 型号： | GT-48001A |
| 厂商： | Galileo Technology Services, LLC |
| 英文描述： | Switched Ethernet Controller For 10BaseX(10BaseX交换式快速以太网控制器) |
| 中文描述： | 交换式以太网控制器10BaseX（10BaseX交换式快速以太网控制器） |
| 文件页数： | 11/101页 |
| 文件大小： | 1235K |
| 代理商： | GT-48001A |
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GT-48001A Switched Ethernet Controller
Revision 1.6
17
4.3
Address Aging
The GT-48001A includes hardware support for address aging, which requires the use of a CPU to be implemented.
The GT-48001A gives an indication to the CPU of the relative “age” of an address by setting the Aging bit in the
address table when it receives a packet. The CPU reads the Aging bit each aging period (the default from the 802.12d
specification is 300 seconds) and clears the bit. If in the next period, the bit remains clear, the CPU knows that this sta-
tion didn't transmit any packet in this period of time and the address can be removed from the table.
Note that the aging bit is set only in the GT-48001A device that received the packet; other GT-48001A’s in the system
are not notified since, by definition, the receiving device “owns” the address.
The only time the GT-48001A will delete an entry by itself is when a user changes the location of a station. The GT-
48001A will then automatically learn the new location of the station the next time the station sends a packet.
4.4
Static Addresses
The GT-48001A includes support for “static” MAC addresses. IEEE 802.1d chapter 3.9.1: "Static entries may be added
to and removed from the filtering database under explicit management control. They are not automatically removed by
any timeout mechanism". This means that when an address is selected to be static, it will not be removed from the
address table during aging.
During normal address recognition, if an address is static, the GT-48001A will not update its address table parameters
and will not send a NEW_ADDRESS message over the PCI (if the address has changed ports.)
4.5
Address Recognition Failure
It is possible that an address recognition cycle will fail when more than 8K addresses have already been entered into
the address table. In the case of an address recognition failure the packet will be treated as unknown and forwarded to
all ports. An interrupt is also generated to the CPU (if any.)
Address recognition failures are not fatal and do not need to be handled (e.g. designers of unmanaged systems need
not worry about them.) Managed systems may want to “clean” the address table of old addresses when such a failure
occurs (see Section 4.4).
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| GT-48208 | Advanced Switched Ethernet Controllers for 10+10/100 BaseX(高级交换式 10+10/100 BaseX以太网控制器) |
相关代理商/技术参数 |
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| GT482 | 制造商:CORNELL DUBILIER ELECTRONICS 功能描述:Cap Ceramic 82pF 3000V SL 5% (12 X 6mm) Radial 9.5mm 85°C |
| GT48212-A6-PBB1C000 | 制造商:Marvell 功能描述: |
| GT48212-A6-PBB-C000 | 制造商:Marvell 功能描述:12 PORT E + 2 PORT FE SWITCH (MANAGED) - Trays |
| GT48300-A1-BBE1C083 | 制造商:Marvell 功能描述:Marvell GT48300-A1-BBE1C083 |
| GT48300-A1-BBE-C000 | 制造商:Marvell 功能描述:Marvell GT48300-A1-BBE-C000 |
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