Overview of the Model 5782 ATM Virtual Network Router
119557-A Rev. 00
1-9
Figure 1-3.
SVC/PVC Signaling Protocol Stack
Data Encapsulation
Bay Networks ATM routers support multiprotocol encapsulation (as defined in
RFC 1483), enabling the router to multiplex (combine) and demultiplex (separate)
bridged or routed protocol data units (PDUs).
For transmission, the encapsulation process adds a header from 2 to 8 octets in
length to the PDU to allow decoding. The decoding process determines the proper
service access point (SAP).
When receiving information, the encapsulation method evaluates the header to
determine whether the PDU is a valid routed or bridged cell. If it is valid, the
encapsulation method then strips the header from the cell and passes it to the
appropriate SAP for routing or bridging.
You can choose from four data encapsulation types:
•
LANE 802.3
•
LANE 802.5
•
LLC/SNAP
•
NLPID
•
NULL
6786
Q.2931
Q.SAAL
Adaptation layer
(AAL 5)
ATM layer
Physical layer
Protocol
Data
encapsulation
