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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
Chapter6 Card and Service Configuration
Eight-Port Circuit Emulation Service Modules
Cell Delay Treatment
For each connection, you can co n figur e a to le rable variation in the cell arrival tim e ( CDVT) acc or d in g
to the expected reliability of th e route. The CDVT applies to the receive bu ffer. After an un d er r un, t he
receiver places the contents of the firs t cel l t o arrive in a receive buffer then plays it ou t at least one
CDVT value later. For each VC, the maximum c ell delay and CDVT (or jitter) are:
•For T1
–
Cell delay of 48 msec
–
CDVT of 24 msec in increments of 125 microseconds
•For E1
–
Cell delay of 64 msec
–
CDVT of 32 msec in increments of 125 microseconds
Redundancy Support for the Eight-Port CESM
The AX-CESM-8T1 and AX-CESM-8E1 can have 1:N redundancy support but with some variations
between the T1 and E1 modes of operation. The type of redundancy and the type of back card are
interdependent. See “Service Resource Module” for more details. I n ge neral:
•With an RJ48-8T1, an MGX-SRM-3T3 can provide 1:N redundancy through the distribution bus or
the redundancy bus.
•With an RJ48-8E1, an MGX-SRM-3T3 can provide 1:N redundancy through the redundancy bus.
Back card requirements for the MGX-SRM-3T3 and service modules vary, as follows:
•If you are using the MGX-SRM-3T3 for bulk distribution of T1 channels, the CESMs do not use
back cards, but each MGX-SRM-3T3/C must have an MGX-BNC-3T3-M back card. (Bulk
distribution is not availab l e for E1 operation.)
•If the MGX-SRM-3T3/C supports T1 or E1 1:N redundancy through the redundancy bus (no bulk
distribution), the MGX-SRM-3T3/C does not require a back card, but the N CESM primary cards
must have one redundant version of the back card.
Error and Alarm Response
When it detects a loss of sign al ( LO S) ala rm, the CESM notifies the conn ect ed C P E i n t he u pst r eam
direction after an integratio n period. The CESM continu es t o em i t c ells but sets the ATM cell payload
with an appropriate data pattern as spec ified by the ATM Forum CES V2.0 specification. Also, an OAM
cell with RDI code goes to th e far en d to indicate out of service. See Ta ble 6-4 .
Table6-4 CESM Errors and Alarms
Error Alarm
Type Down
stream Up Stream Comments
Link Failure
(RX) Blue (LOS) AIS—OAM
cells none Data cells According to ATM-Forum
CES-IS V 2.0
Receive RAI Yellow None None