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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Frame Relay Service Modules (FRSMs)
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.
FRSMs for T1 and E1 lines
There are two types of FRSM modules for T1 and E1 lines—Franctional (unchannelized) modules and
channelized modules. Both these module types offer 1:N redundancy via the optional SRM (see Service
Resource Modules, page 2-22).
Fractional FRSMs
Each interface of a fractional FRSM supports a single port at 56 kbps or nx64 kbps.
Each port can be independently configured to run Frame Relay UNI (FR-UNI), Frame Relay NNI
(FR-NNI), ATM-FUNI, or frame forwarding as described in FRSM Connection Types, page 4-2.
Fractional FRSM cards include
• AX-FRSM-4T1/E1: four E1 or T1 interfaces. The 4-port FRSM supports up to a maximum of 256
connections (virtual circuits), which can be allocated across the T1 or E1 lines in any manner.
• AX-FRSM-8T1/E1: eight E1 or T1 interfaces. The 8-port FRSM supports a maximum of 1,000
connections. The maximum frame size is 4510 bytes for Frame Relay and 4096 for ATM-FUNI.
Channelized FRSMs
Each interface of a channelized FRSM supports multiple ports at 56 kbps or nx64 kbps.
Each port can be independently configured to run Frame Relay UNI (FR-UNI), Frame Relay NNI
(FR-NNI), ATM-FUNI, or frame forwarding as described in FRSM Connection Types, page 4-2.
Channelized FRSM cards include
• MGX-FRSM-8T1-C—eight channelized T1 interfaces support 24 ports per interface.
• MGX-FRSM-8E1-C—eight channelized E1 interfaces support 31 ports per interface.
The 8-port channelized FRSM supports a maximum of 1,000 connections.
Figure 4-3 is an illustration of 4-port and an 8-port FRSM front cards for T1 or E1 lines.