Alcatel Carrier Internetworking Solutions 6648 - Manual (Page 348)

Roma
page -24 OmniSwitch Troubleshooting Guide September 2005
Flow Control
Coupon and paycheck thresholds are set for unicast and IPC queues (multicast is limited by Coronado for
fabric ingress). These thresholds are used to generate ingress backpressure and paycheck messages. Each
Roma ASIC participating as an operational bit slice is responsible for 2 NIs according to the scheme: bit
slice n is responsible for NI slots 2(n+1) and 2(n+1)-1. Bit slices are zero-based (0 - 7); NI slots are one-
based (1 - 16).
In order to support basic system operation, the Roma driver must maintain the correct destination port
mapping on the Roma ASIC chips, including any required multicast and IPC port mapping; appropriate
internal flow control thresholds should be maintained as well. These form a small but significant part of
the initialization process and the Roma driver needs to adapt in case of changes to NI slot configuration.
However, the high level sequencing and selection of Roma Driver activity is mostly a function of a set of
external events, most of which can be termed “hot swap” events. The following 10 scenarios represent
high-level states for the Roma Driver which correspond to its handling of some kind of major.
Initialization
This state is entered when the Roma Driver is first spawned as a task on the primary CMM. Early on, the
fabric slot and NI slot configuration must be completely determined to effectively program the Roma
ASICs. An overview of the ASIC setup follows:
• Bit Slice oriented setup - includes programming chip IDs and master chip selection.
• Fabric Port setup - includes calendar, flow control, and multicast vector setup
• Synchronizing Roma chips - includes starting primary cycle and timer resets
• Manual link acquisition - verify that all links are up, includes retries
• Automatic HW recovery mechanism setup - includes link acquisition and hot swap
• During switch operation, this is the state that the Roma Driver will be in the vast majority of the time.
Remaining in this state implies there are no changes to: physical Fabric slot configuration, NI slot
configuration, the primary CMM slot, or detected framing errors. Processing in this state consists of an
infinite loop where the following tasks are performed:
• Respond to interrupts and use low intensity poll for backup
• Check messages for updates to multicast vector and board changes
• Synchronize the multicast vector shadow table when 2 CMMs are present
• Maintain statistical counts and rates
Fabric Slot Insertion
This state assumes that four operating fabric slots are currently occupied. The state is entered when a fifth
fabric card is inserted into the remaining available slot. This card should not disturb the operational fabric,
and it will assume the role of redundant fabric card.