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Chapter 10 Bridge Configuration
Confidential and Proprietary Information of ZTE CORPORATION 151
ATM Interface Bridge
ATM Interface Bridge consists of following topics which are in
below table.
Topic Page No
ATM Interface Bridge 151
Configuring ATM Bridge 152
ATM Interface Bridge
Bridge function of the ATM interface is same as that of the POS
interface, covering layer 3 functions and transparent
transmission function of the bridge interface.
Layer 3 function of the bridge interface indicates that the ATM
link is directly connected with the Ethernet with encapsulation in
the RFC2684B message format. The ATM layer 3 interface
encapsulated in the RFC2684B message format can serve as an
Ethernet interface and has attributes of the Ethernet interface,
such as ARP learning.
The transparent transmission function of the ATM bridge
interface is implemented through V_Switch functions. With the
V_Switch forwarding table, transparent transmission is available
between the ATM interface and the Ethernet and POS interfaces.
ATM is the transmission mode in which the cell serves as the
basic carrier. It is required to segment the user information of
different lengths into short cells with the fixed length or form the
user information of different lengths again through short cells
with the fixed length.
RFC2684 does not specify a new method for segmentation and
reassembly (SAR) to route and bridge the protocol data unit
(PDU) but makes the load area of the Common Part
Convergence Sublayer (CPCS) of ATM Adaption Layer 5 (AAL5)
to carry the PDU. RFC2684 describes two methods to carry
connectionless network interconnection service information,
route and bridge PDUs on the ATM network.
In the first method, multiple protocols can be reused on the
single ATM virtual circuit. The protocol type carrying the PDU is
identified by adding a Logic Link Control (LLC) title specified in
the IEEE802.2 standard to the PDU. This method is called “LLC
encapsulation”. Using this method needs a few virtual circuits in
the multi-protocol environment.
The second method is to imply higher-layer protocols to ATM
virtual circuits. This method is called “VC-based multi-channel
reuse”. To use multiple protocols, configure virtual circuits for
each protocol.
Bridge
Function
Layer 3
Function
Transport
Transmission
Common Part
Convergence
LLC
Encapsulation
ATM Virtual
Circuits