3Com PathBuilder S200 Series Owner's Manual page 54

Transparent Bridging for Ethernet LANs
Forwarder/
Hardware
Accelerator and
LAN/WAN Handlers
Hardware
Accelerator
Functions
50
Figure 28 shows the relationship of the Forwarder and Hardware Accelerator to the
LAN and WAN Handlers.
LAN
1
Handler
Figure 28. Relationship of Forwarder and Hardware Accelerator to LAN
and WAN Handlers
The Hardware Accelerator performs these functions:
• Discards local traffic before it reaches the node
• Participates in the learning process for LAN traffic
• Participates in the aging process for LAN traffic
The Hardware Accelerator applies the aging process to the learned addresses on a
LAN port. It needs to:
• Set the aging timer bit for each address learned on the LAN link.
• Reset the aging timer bit for the entry whenever a frame with the same source
address passes through the bridge
• Decrement the aging timer bit when it receives periodic timeout notification
from the Forwarder
• Remove all the aged-out entries from the Hardware Accelerator database
The statistics which show the number of local traffic frames discarded by the
Hardware Accelerator are displayed on the LAN port Statistic CTP menu.
5
TB
Forwarder Handler
36
HW
Accelerator
1
WAN
32
Bridging