User Guide: PTP 600 Series
Ethernet bridging
phn-0896_012v000
Jul 2010
1-39
Source address learning
If Local Packet Filtering is enabled, the PTP 600 learns the location of end stations
from the source addresses in received management frames. The agent filters
transmitted management frames to ensure that the frame is transmitted at the
Ethernet port, or over the wireless link as appropriate. If the end station address is
unknown, then management traffic is transmitted at the Ethernet port and over the
wireless link.
Wireless link down alert
The PTP 600 Series provides an optional indication of failure of the wireless link by
means of a brief disconnection of the Copper data port or the Fiber data port. The
Wireless link down alert can be used to trigger protection switching by Spanning Tree
Protocol (STP) or Ethernet Automatic Protection Switching (EAPS) in a redundant
network.
Back-to-back links
PTP 600 will not operate correctly if a direct cabled connection is made between two
PIDUs. Where two or more links are deployed in a chain, always use an Ethernet
switch or router to interconnect the links at the relay points.
Protocol model
Ethernet bridging behavior at each end of the wireless link is equivalent to a two-port,
managed, transparent MAC bridge where the two ports are:
•
Ethernet Port
•
Wireless Port
Frames are transmitted at the Wireless port over a proprietary point-to-point circuit-
mode link layer between ends of the PTP 600 link. Ethernet frames received at the
Ethernet port, or generated internally within the management agent, are encapsulated
within a lightweight MAC layer for transmission over the wireless link.
Protocol layers involved in bridging between Ethernet and wireless interfaces are
shown in
Figure 1-20
. Protocol layers involved in bridging between external interfaces
and the management agent are shown in
Figure 1-21
. In these figures, the layers have
the meanings defined in IEEE 802.1Q-2005.
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