User's Guide Part 1

Chapter 1: Product description Ethernet bridging
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 a wired Ethernet port allocated to
the Data Service, Second Data Service, Out-of-Band Management Service, and the Wireless
port.
Frames are transmitted at the Wireless port over a proprietary point-to-point circuit-mode link
layer between ends of the PTP 700 link. The Wireless Port provides two distinct service access
ports (SAPs) where the first is always used for the Data Service, while the second is used by
either the Second Data Service or Out-of-Band Management Service.
Ethernet frames received at the Ethernet ports, 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 3. Protocol layers involved in bridging between external interfaces and the management
agent are shown in Figure 4. In these figures, the layers have the meanings defined in IEEE
802.1Q-2005.
Figure 3
Protocol layers between Ethernet and wireless interfaces
Wireless PortEthernet Port
IEEE 802.3
Media Access Method
Independent
Functions
Media Access Method Dependent
Convergence Functions
Media Access Method
Specific Functions
Ethernet Wireless
PTP Medium Access
Method
PTP Security
(Optional)
PTP Physical Layer
MAC Relay Entity
D-SAP = Data Service Access Point
2D-SAP = Second Data Service Access Point
M-SAP = Management Service Access Point
Page 1-29