参数资料
型号: ZL50408GDC
厂商: CONEXANT SYSTEMS
元件分类: 网络接口
英文描述: DATACOM, LAN SWITCHING CIRCUIT, PBGA208
封装: 17 X 17 MM, 1.40 MM HEIGHT, MO-192, LBGA-208
文件页数: 78/144页
文件大小: 1779K
代理商: ZL50408GDC
ZL50408
Data Sheet
39
Zarlink Semiconductor Inc.
and CPU ports, to map the 8 transmit priorities into 4 multicast queues, the LSB is discarded. The priority mapping
can be modified through memory configuration command. The multicast queue that is in FIFO format shares the
space in the internal memory block. The size and starting address can also be programmed through memory
configuration command.
During scheduling, the TxQ manager treats the unicast queue and the multicast queue of the same class as one
logical queue. The older head of line of the two queues is forwarded first. The port control requests a FCB release
only after the EOF for the multicast frame has been read by all ports to which the frame is destined.
4.3
Frame Forwarding To and From CPU
Frame forwarding from the CPU port to a regular transmission port is nearly the same as forwarding between
transmission ports. The only difference is that the physical destination port must be indicated in addition to the
destination MAC address.
Frame forwarding to the CPU port is nearly the same as forwarding to a regular transmission port. The only
difference is in frame scheduling. Instead of using the patent-pending Zarlink Semiconductor scheduling algorithms,
scheduling for the CPU port is simply based on strict priority. That is, a frame in a high priority queue will always be
transmitted before a frame in a lower priority queue. There are four output queues to the CPU and one receive
queue.
5.0
Search Engine
5.1
Search Engine Overview
The ZL50408 search engine is optimized for high throughput searching, with enhanced features to support:
Up to 4 K of Unicast/Multicast MAC addresses and IP Multicast addresses
Up to 4 K VLANs
Up to 8 groups of port trunking
Traffic classification into 2 (or 4 for GMAC) transmission priorities, and 2 drop precedence levels
Packet filtering based on MAC address, Protocol or Logical Port number
Security
Up to 4 K IP Multicast groups
Individual Flooding, Broadcast, Multicast Storm Control
MAC address learning and aging
5.2
Basic Flow
Shortly after a frame enters the ZL50408 and is written to the Frame Data Buffer (FDB), the frame engine generates
a Switch Request, which is sent to the search engine. The switch request consists of the first 64 bytes of the frame,
which contain all the necessary information for the search engine to perform its task. When the search engine is
done, it writes to the Switch Response Queue, and the frame engine uses the information provided in that queue for
scheduling and forwarding.
In performing its task, the search engine extracts and compresses the useful information from the 64-byte switch
request. Among the information extracted are the source and destination MAC addresses, the packet’s VLAN ID,
and whether the frame is unicast or multicast or broadcast. Requests are sent to the SRAM to locate the associated
entries in the MCT table.
When all the information has been collected from the SRAM, the search engine has to compare the MAC address
on the current entry with the MAC address for which it is searching. If it is not a match, the process is repeated on
the internal MCT Table. All MCT entries other than the first of each linked list are maintained internal to the chip. If
the desired MAC address is still not found, then the result is either learning (source MAC address unknown) or
flooding (destination MAC address unknown).
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ZL50409 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 9-Port 10/100M Ethernet Switch
ZL50409GDC 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 9-Port 10/100M Ethernet Switch
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ZL50410 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 8-Port 10/100M + 1-Port 10/100/1000M Ethernet Switch