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Cisco MGX 8230 Edge Concentrator Installation and Configuration
Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
Chapter 2 Module and Service Descriptions
Frame Relay Service Modules
Congestion Indication
The FRSM maps congestion indication in both directions:
Congestion Indication mapping is provided in both directions
FUNI-to-ATM Direction
EFCI is set to 0 for every ATM cell generated by the segmentation process.
ATM-to-FUNI Direction
If the EFCI field in the last ATM cell of a received segmented frame is set to 1, the CN bit in the FUNI
header is set to 1. The two reserve bits (the same positions as C/R and BECN in Frame Relay header)
are always set to 0.
Types of Frame Service Modules
There are three types of FRSMs:
• FRSMs for T1 and E1 Lines, page 2-27.
• FRSMs for T3 and E3 lines, page 2-32.
• FRSMs for Serial Connections, page 2-38.
Note For hardware and other specifications on the FRSMs, refer to Appendix A, “Technical
Specifications.” For descriptions of how to configure the card, lines, and ports and add Frame Relay
connections, refer to Chapter 6, “Card and Service Configuration”
FRSMs for T1 and E1 Lines
The eight-port FRSMs for T1 or E1 lines support channelized or unchannelized service. These cards
include the following:
• AX-FRSM-8T1: supports up to eight fractional T1 line interfaces.
• AX-FRSM-8E1: supports up to eight fractional E1 line interfaces.
• AX-FRSM-8T1-C: supports up to eight channelized T1 line interfaces.
• AX-FRSM-8E1-C: supports up to eight channelized E1 line interfaces.
FRSM for T1 features
The FRSM-8T1 and FRSM-8T1-C each provide eight T1 interfaces for full-duplex communications at
up to 1.544 Mbps.
Each T1 line consists of an RJ-48, along with three LED indicators for line status. The FRSM-8T1
supports fractional and unchannelized T1 port selection on a per-T1 basis. The FRSM-8T1-C allows full
DS0 and n x DS0 channelization of the T1s, for a maximum of 192 ports per FRSM-8T1-C.
Key Features include:
• Eight T1 (1.544 Mbps +/-50 bps or 32 ppm) lines
• B8ZS or AMI line coding
• ANSI T1.408 extended superframe format line framing