Altera SerialLite II Protocol - Manual (Page 43)

Altera Corporation 43
SerialLite II Protocol Reference Manual
SerialLite II Specification
Figure 2–22. Packet Nesting Example
Packet Nesting Rules
The following packet nesting rules must be followed:
1. Nested packets must be started on lane number 0 of a new column.
2. Priority packets cannot be nested in other priority packets.
3. Data and priority packets must follow the packet interleaving rules
as defined in
“Packet Interleaving Rules” on page 2–43 .
Interleaved Data Packets
For applications that require bursting and nesting, SerialLite II allows the
the transmission of packets to be suspended and continued. Interleaving
is supported for both priority and data packets. The suspend user packet
(SUP) character interrupts the current packet and continuation of data
packet (CDP) and continuation of priority packet (CPP) identifies the
switch to a different channel address. For more information on channel
multiplexing see
“Channel Multiplexing” on page 2–56 .
There will be an impact on bandwidth efficiency as additional overhead
is associated with suspending and continuing packets. To minimize the
overhead impact, switch between packet channel numbers on large
bursts. Suspending and continuing to the same channel number is
allowed, but it consumes additional bandwidth. The suspension of a
priority packet must be done on the segment size boundary.
Packet Interleaving Rules
The following packet interleaving rules must be followed:
1. The suspend user packet sequence {SUP} must be transmitted on
lane number 0.
SLP Link Management
SPP Prioirity Payload EGP
SDP Data Payload EGP
SDP SPP SUP EGP EGP CDP SLP Link Management Priority Priority Data Data