IBM PowerPRS Q-64G
Preliminary
Packet Routing Switch
Table 3-20. Egress Data Packet and Control Packet, H0 Byte
Information Carried
Byte
Bit 0
Bit 1
Bits 2:3
Bit 4
Bit 5
Bits 6:7
H0
Grant type
Parity
Protection
Best effort
Reserved
Reserved
Packet priority
(high channel)
H0
Memory grant
Parity
Protection
Best effort
Packet priority
(low channel)
Table 3-21. Egress Data Packet and Control Packet, Byte H0 Field Descriptions
Bit(s)
Field Name
Description
Identifies the type of grants carried in byte H1 of the packet header:
0
1
Subport grants (default value)
Multicast grants (set to ‘1’ every 61 packet cycles or when the multicast grant status
changes)
Grant Type
(high channel)
0
These bit settings operate the same as those for egress idle packets (see Table 3-11). Byte H1 is
also formatted the same as it is for egress idle packets (see Tables 3-12 through 3-16).
Memory Grant
(low channel)
Reports the status of the memory grant.
Header parity.
1
Parity
This field is processed without modification. See the ingress data packet and control packet byte H0
field descriptions in Table 3-5 on page 34.
2:3
Protection
This bit is processed without modification. See the ingress data packet and control packet byte H0
field descriptions in Table 3-5.
4
Best Effort
Reserved
Reserved.
This field is processed without modification. See the ingress data packet and control packet byte H0
field descriptions in Table 3-5.
6:7
Packet Priority
3.3.9 Egress Service Packet Format
The egress service packet format for the PowerPRS Q-64G 16-Gbps configuration is presented in Figure 3-7.
The packet qualifier byte (H0) is described in Tables 3-22 and 3-23. Header bytes H1 and H2 of egress data
packets and control packets are identical to those of egress idle packets (see Tables 3-12 through 3-16).
prsq-64g.01.fm
December 20, 2001
Functional Description
Page 45 of 199
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