Ericsson MINI-LINK BAS User Manual

4-5 MINI-LINK BAS
EN/LZB 111 0542 P2B Technical Description
In the LLC multiplexing option the LLC and SNAP fields are inserted
to identify the type of bridged protocol data unit. In the VC
multiplexing these fields are not required, as indicated in the figure, as
the protocol data unit type is associated to a specific VC. This option
allows therefore to decrease the encapsulation overhead and is
recommended whenever supported by the equipment terminating the
RFC1483 protocol, such as the external router shown in the Figure
4-2.
The ATM Adaptation Layer 5 (AAL5) is used to segment the frames
in cells and insert also an FCS field additional to the one available in
the Ethernet frames. The Ethernet FCS field can therefore be omitted
in the encapsulated frame to save bandwidth. In this case it is
reinserted when the Ethernet frame is rebuilt. The presence of the FCS
field can be set by the EM.
6 bytes
5
Dest. Mac
Address
Preamble
Start
Frame
7 bytes 1 bytes 6 bytes
Source
Address
Type
2 bytes 46-1500 bytes
Data
FCS
4 bytes
Ethernet
LLC
3 bytes
5 bytes
2 bytes
0-47 bytes
RFC 1483 Encapsulation
SNAP Pad Data
FCS encapsulation
is a provisonable
options.
LLC or VC based
multiplexing is a
provisonable option
AAL-5 CPCS-PDU
1 bytes 1 bytes 2 bytes 4 bytes
CPCS-PDU Payload Pad CPCS-UU CPI Length FCS
A
U
U
=0
A
U
U
=0
A
U
U
=0
A
U
U
=0
A
U
U
=1
ATM-cells
5 bytes 48 bytes 5 bytes 5 bytes 5 bytes 5 bytes48 bytes 48 bytes 48 bytes 48 bytes
Figure 4-3. Ethernet Frame Encapsulation on ATM in the AT

Ericsson MINI-LINK BAS Specifications

General

Brand	Ericsson
Model	MINI-LINK BAS
Category	Wireless Access Point
Language	English