Specifications
6-44
Cisco MGX 8230 Edge Concentrator Installation and Configuration
Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
Chapter 6 Card and Service Configuration
Eight-Port Circuit Emulation Service Modules
Cell Delay Treatment
For each connection, you can configure a tolerable variation in the cell arrival time (CDVT) according
to the expected reliability of the route. The CDVT applies to the receive buffer. After an underrun, the
receiver places the contents of the first cell to arrive in a receive buffer then plays it out at least one
CDVT value later. For each VC, the maximum cell 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. In general:
• 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 available 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 signal (LOS) alarm, the CESM notifies the connected CPE in the upstream
direction after an integration period. The CESM continues to emit cells but sets the ATM cell payload
with an appropriate data pattern as specified by the ATM Forum CES V2.0 specification. Also, an OAM
cell with RDI code goes to the far end to indicate out of service. See Table 6-4.
Table 6-4 CESM Errors and Alarms
Error
Alarm
Typ e
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