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参数资料
| 型号： | ZL50408GDG2 |
| 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, LEAD FREE, MO-192, LBGA-208 |
| 文件页数： | 91/144页 |
| 文件大小： | 1779K |
| 代理商： | ZL50408GDG2 |
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ZL50408
Data Sheet
50
Zarlink Semiconductor Inc.
See Programming Flow Control Registers application note, ZLAN-44, for more information.
7.7.1
Unicast Flow Control
For unicast frames, flow control is triggered by source port resource availability. Recall that the ZL50408’s buffer
management scheme allocates a reserved number of FDB slots for each source port. If a programmed number of a
source port’s reserved FDB slots have been used, then flow control Xoff is triggered.
Xon is triggered when a port is currently being flow controlled, and all of that port’s reserved FDB slots have been
released.
Note that the ZL50408’s per-source-port FDB reservations assure that a source port that sends a single frame to a
congested destination will not be flow controlled.
7.7.2
Multicast Flow Control
Flow control for multicast frames is triggered by a global buffer counter. When the system exceeds a programmable
threshold of multicast packets, Xoff is triggered. Xon is triggered when the system returns below this threshold.
Note:
If per-port flow control is on, QoS performance will be affected.
7.8
Mapping to IETF Diffserv Classes
The mapping between priority classes discussed in this chapter and elsewhere is shown below.
As the table illustrates, the classes of Table 9 are merged in pairs— P3 is used for network management (NM) and
expedited forwarding service (EF) frames. Classes P2 and P1 correspond to an assured forwarding (AF) group of
size 2. Finally, P0 is for best effort (BE) class.
Features of the ZL50408 that correspond to the requirements of their associated IETF classes are summarized in
the table below.
7.9
Failover Backplane Feature
The ZL50408 implements a hardware assisted link failure detection mechanism utilizing a Link Heart Beat (LHB)
packet. The LHB packet format is defined as a 64-byte MAC control frame with a user defined opcode. The packet
format is illustrated below:
ZL50408
P3
P2
P1
P0
IETF
NM+EF
AF0
AF1
BE
Table 9 - Mapping to IETF Diffserv Classes for
GMAC & CPU Ports
Network management (NM) and
Expedited forwarding (EF)
Global buffer reservation for NM and EF
Shaper for traffic on uplink port
No dropping if admission controlled
Assured forwarding (AF)
Global buffer reservation for two AF classes
Shaper for traffic on uplink port
Random early discard, with programmable levels
Best effort (BE)
Service only when other queues are idle means that QoS not
adversely affected
Shaper for traffic on uplink port
Random early discard, with programmable levels
Traffic from flow control enabled ports automatically classified as BE
Table 10 - ZL50408 Features Enabling IETF Diffserv Standards
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| ZL50409GDC1 | 制造商:Microsemi Corporation 功能描述: |
| 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 |
| ZL50410GDC208 | 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 |
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