ZL50405GDC ZARLINK [Zarlink Semiconductor Inc], ZL50405GDC Datasheet - Page 47

• Manufacturer Part Number: ZL50405GDC
• Description: Managed5-Port 10/100 M Ethernet Switch
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

7.9
The ZL50405 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-xx-xx-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 ZL50405 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.
8.0
See Port Trunking application note, ZLAN-48, for more information.
8.1
A port group (i.e. trunk) can include up to 4 physical ports to form a fault tolerant link. There are eight trunk groups
total.
Load distribution among the ports in a trunk for unicast is performed using hashing based on source MAC address
and destination MAC address. Three other options include source MAC address only, destination MAC address
only, and source port (in bidirectional ring mode only). Load distribution for multicast is performed similarly.
If a VLAN includes any of the ports in a trunk group, all the ports in that trunk group should be in the same VLAN
member map.
Network management (NM) and
Expedited forwarding (EF)
Assured forwarding (AF)
Best effort (BE)
Failover Backplane Feature
Features and Restrictions
Port Trunking
01-80-C2-00-00-01
Table 11 - ZL50405 Features Enabling IETF Diffserv Standards
xx-xx-xx-xx-xx-xx
Global buffer reservation for NM and EF
Shaper for traffic on uplink port
No dropping if admission controlled
Shaper for traffic on uplink port
Random early discard, with programmable levels
adversely affected
Shaper for traffic on uplink port
Random early discard, with programmable levels
Traffic from flow control enabled ports automatically classified as BE
Global buffer reservation for two AF classes
Service only when other queues are idle means that QoS not
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ZL50405
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Data Sheet