zl50404 Zarlink Semiconductor, zl50404 Datasheet - Page 40

• Manufacturer Part Number: zl50404
• Description: Lightly Managed/unmanaged 5-port 10/100m Ethernet Switch
• Manufacturer: Zarlink Semiconductor

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 ZL50404 that correspond to the requirements of their associated IETF classes are summarized in
the table below.
7.9
The ZL50404 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:
Where “xx-xx-...” is the source port MAC address and “yy-yy” is the special opcode defined by register setup
(LHBReg0,1). The opcode “00-01” is reserved for the flow control packet. We recommend opcode “00-12” for the
LHB packet.
The LHB is done between two compatible MACs providing this function. A timer parameter will be set for both the
receiver and transmitter (LHBTimer).
On the transmission side, the MAC will monitor the transmission activities. If there is no activity for more than the
set period, a LHB packet will be sent to its link partner. Therefore, there should always be at least one packet
transmitted from the MAC for every period specified.
On the receiving side, the MAC will also monitor the activity. If there is no good packet received for more than 2X
the set period, an alarm will be raised to the CPU. The LHB packet is only used by the ZL50404 to reset the timeout
counter, it is ignored otherwise (i.e. not passed on within the system).
See the Failover Protection Application Note, ZLAN-43, for more information.
Network management (NM) and
Expedited forwarding (EF)
Assured forwarding (AF)
Best effort (BE)
Failover Backplane Feature
01-80-c2-00-00-01
Table 9 - Mapping to IETF Diffserv Classes for MMAC & CPU Ports
Table 10 - ZL50404 Features Enabling IETF Diffserv Standards
ZL50404
IETF
xx-xx-xx-xx-xx-xx
Global buffer reservation for NM and EF
Shaper for traffic on uplink port
No dropping if admission controlled
Global buffer reservation for two AF classes
Shaper for traffic on uplink port
Random early discard, with programmable levels
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
NM+EF
P3
Zarlink Semiconductor Inc.
ZL50404
40
AF0
P2
88-08
AF1
P1
yy-yy
00-00-...
BE
P0
CRC
Data Sheet