
ABM-3G
PXF 4333 V1.1
Functional Description
Data Sheet
58
2001-12-17
3.3.1
LCI Translation in Mini-Switch Configurations
In Uni-directional applications, the ABM-3G can be programmed to make a minimum
header translation. This is necessary in a Mini-Switch configuration as both the forward
and backward direction of a connection traverse the devices in the same direction. The
OAM functions in the Infineon ALP (PXB 4350) or AOP (PXB 4340) devices need the
same LCI for forward and backward direction of a connection.
This is clarified by the example shown in
Figure 3-13
in which a connection is set up
from PHY
1
to PHY
2
. VPI/VCI
1
is the identifier on the transmission line where PHY
1
is
connected. The terminal sends ATM cells with this identifier and expects cells in the
backward direction from PHY
2
with the same identifier. The ALP in the upstream
direction translates VPI/VCI
1
into LCI
1
, the unique local identifier for this connection in
the upstream direction. Similarly, for the backward connection from PHY
2
to PHY
1
, the
ALP receives ATM cells from PHY
2
with the identifier VPI/VCI
2
and translates them into
LCI
2
.
Figure 3-13
Connection Identifiers in Mini-Switch Configuration
For minimum complexity, the header translation of the ABM-3G is done by inverting the
Least Significant Bit (LSB) of the LCI. This measure divides the available LCI range into
two parts:
odd
LCI values for forward connections and
even
LCI values for backward
connections (or vice-versa). That is, it reduces the available number of connection iden-
tifiers to 8192, because two LCI values are used per connection.
This is not a restriction in the case of arbitrary address reduction modes as, for example,
ABM-3G Uni-directional mode)
ALP
PXB
4350
AOP
PXB
4340
VPI/VCI
1
LCI
1
LCI
1
VPI/VCI
2
LCI
2
LCI
2
LCI
1
LCI
1
LCI
2
LCI
2
Cores
HT = Header Translation
LCI = Local Connection Identifier
HT
HT
LCI=
LCI+/-1
Phy 1
Phy 2