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Description of Connection Types on the FRSM
PVC Status Management
The management of ATM layer and FR PVC status management can operate independently. The
PVC status from the ATM layer is used when determining the status of the FR PVC. However, no
direct actions of mapping LMI A bit to OAM AIS is performed.
Frame Relay-to-ATM Service Interworking
By specifying a service interworking (SIW) channel type when you add a Frame Relay PVC to an
FRSM, all data is subject to SIW translation and mapping in both the Frame Relay-to-ATM and
ATM-to-Frame Relay directions. A BPX 8620 network with SIW connections appears in Figure 6-3.
Figure 6-3
ATM FUNI CPE
ATM UNI CPE
In Figure 6-3, an MGX 8850 node on the right has three Frame Relay SIW connections terminating
on an FRSM. Three far-end terminations for these connections appear in other parts of Figure 6-3:
•
ATM FUNI (framed UNI) port on an FRSM
•
ATM UNI port on an RPM
•
ATM UNI port on a BPX 8600-series BXM card
In addition to frame-to-cell and DLCI-to-VPI/VCI conversion, SIW maps cell loss priority and
congestion data between the Frame Relay and ATM formats and is FRF.8-compliant. It provides full
support for routed and bridged PDUs, transparent and translation modes, and VP translation.
Cell Loss Priority
In addition to frame-to-cell and DLCI-to-VPI/VCI conversion, the SIW feature maps cell loss
priority (CLP) and congestion information from Frame Relay-to-ATM formats.
You can modify the CLP and congestion indicators for individual connections. On the CLI., use the
cnfchanmap command. In the Frame Relay-to-ATM direction, you can specify one of the following
discard eligibility (DE)-to-cell loss priority (CLP) schemes for an individual SIW connection:
•
DE bit in the Frame Relay frame is mapped to the CLP bit of every ATM cell generated by frame
segmentation.
•
CLP is always 0.
6-24
Cisco MGX 8850 Installation and Configuration, Release 1.1.00, Part Number 78-6186-02
BPX 8600-Series Network with SIW Connections
T1 or E1
FRSM
MGX 8850
RPM
T1 or E1
BPX 8620 network
PVCs
BPX 8620
B
X
M
T3, E3, OC3
ATM-UNI CPE
FR UNI
MGX 8850
FRSM
CPE
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