Qsim/Hsim/Fam Module Overview - 3Com 3C63100-AC-C - PathBuilder S600 Bridge/router Reference Manual

82 C 4: P B
HAPTER ATH UILDER
QSIM/HSIM/FAM
Module Overview
S600 M A
ODULE AND PPLICATION
The PathBuilder S600 supports three Frame Relay modules: QSIM, HSIM, and FAM.
These modules are port, or application, modules for connecting non-ATM devices
to ATM services. Typical device applications include FRADs (Frame Relay Assembler
and Disassembler or Frame Relay Access Devices), channel extenders, FEPs
(Front-End Processors), and routers.
The HSIM module is used to interconnect terminals to DCE devices that must
operate between 3 and 20Mbps.
Table 24 summarizes the basic features of the three Frame Relay modules.
Table 24 PathBuilder S600 Frame Relay Modules
Module Acronym
Quad Serial Interface QSIM
Module
HSSI Module HSIM
Frame Access Module FAM
Each of the Frame Relay modules provides a number of serial interfaces and an
ATM SAR and is able to perform cell-to-frame as well as frame-to-cell conversion.
Frames received from the HDLC serial interfaces are segmented in to cells by SAR
and passed to the ATM backplane. In the other direction, cells received from ATM
backplane will be reassembled into frames and passed to the HDLC serial
interfaces.
A RISC processor on the Frame Relay module performs these functions:
management CPU (MCPU) communication
n
hardware device configuration
n
frame/cell conversion
n
permanent virtual circuit management
n
alarm generation
n
statistical data collection.
n
The SAR contains 15 traffic shapers, each of which can be programmed for
sustained cell rate of transmission, peak cell rate, and maximum burst size.
The traffic shapers work as follows:
The packet is segmented using a dual leaky buffer algorithm, whereby the cells
n
are transmitted from each connection in the shaper at an average rate until the
bucket of tokens fills up (a token is given to the connection at an average rate
if it has no cells to transmit at that moment).
The shaper then turns the burst mode on and transmits at the peak rate for a
n
burst length. Note that the shaper serves every connection independently.
PCR, SCR, and MBS settings are available.
n
O
VERVIEW
# of ports
4
1
8
Type of ports
V.35, RS449, EIA 530, X.21
(64K to 8 Mbps)
HSSI (20 Mbps)
T1 (64K to 1.5 Mbps)