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Circuit Pack Descriptions
7-56 Issue 3 June 2001
— MAC Frame Check Sequence (FCS) Preservation - enable or
disable
— ATM Virtual Path ID and Virtual Channel ID
— IMA group ID
— IMA Frame Length - 32, 64, 128, 256
— ATM scrambler - on/off
— ATM polynomial - on/off.
The IMA link IDs are assigned automatically by the system in the range 0 to
7. The IMA protocol operates in symmetric configuration with common
clock.
â– Alarms:
Local LAN port failures are detected by monitoring for the presence of
either MAC frames or Link Pulses per IEEE 802.3. From the SONET
direction, failures are detected by monitoring for VT1.5 (AIS, LOP), DS1
LOF, Loss of IMA frame, Loss of IMA Delay Synchronization (LODS), Loss
of Cell Delineation (LCD) and excessive AAL5 CRC errors. The alarm level
for a local LAN port failure is user provisionable (Major, Minor, Not
Alarmed).
Control Circuitry 7
The IMA LAN circuit pack interfaces with the SYSCTL via the intra-shelf control
bus. It provides maintenance elements for reporting the status of the circuit pack
and the incoming VT1.5 signal, as well as the circuit pack inventory information
(
CLEI
code, date of manufacture, etc.). The status of the 10/100 BaseT or
100BaseFx LAN signal is also reported as well as data protocol errors at the
MAC, ATM and AAL5 levels. These maintenance elements are used by the
SYSCTL for fault detection and isolation. Conversely, the DS1 responds to control
signals from the SYSCTL (such as FAULT LED control).
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