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5-5
Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Setting up a Frame Relay Connection
Minimum Cell Rate (MCR) is only used with ForeSight (ATFST).
MCR and Peak Cell Rated (PCR) should be specified according to the following formula:
MCR = CIR * 3/800 cells per second
PCR = AR * 3/800 cells per second but less than or equal to 6000
AR = Frame Relay port speed in bps.
The above MCR and PCR formulae assume a fairly pessimistic frame size of 100 octets, however even
smaller frame sizes can result in worst-case scenarios. For example,
The % Util should normally be set to the same value as that used for the Frame Relay segments of the
connection.
FRSM Service Interworking Connections
FRSM service interworking connections are made in the same manner as the network interworking
connections except that chan_type in the MGX 8220 addchan command is specified as service
interworking (transparent or translation) and the connection end that is remote from the MGX 8220 is
an ATM UNI.
FUNI and Frame Forwarding
These services are setup the same as Frame Relay except the for port_type in the addchan command,
which is set as 2 for FUNI or 3 for frame forwarding.
Table 5-1 addcon Parameters
Parameter Description
MCR Minimum Cell Rate
PCR Peak Cell Rate
% Util Percentage utilization of channel
For example, AR equals 64K, PCR = 237, or
AR speed equals 256K, PCR = 950, or
AR speed equals 1536K, PCR = 5703
For a frame size of 64 octects the PCR formula becomes PCR = AR * 2/512 cells per sec
For a frame size of 43 octects the PCR formula becomes PCR = AR * 2/344 cells per sec