The CBS and MBS parameters configure the amount of buffers that a queue can use. The CBS parameter specifies the amount of buffer reserved for a queue in the queue buffer pool. The MBS parameter specifies the portion that a queue can contend for in the shared buffer space. When all reserved buffers for a specific queue are used, the queue contends with other queues for additional buffer resources up to the configured MBS.
On the 7210 SAS-Sx/S 1/10GE, 7210 SAS-Sx 10/100GE, and 7210 SAS-T, the CBS parameter for queues is not configurable for access, network, and access-uplink ports. The CBS is set to system-defined values.
On 7210 SAS-Mxp, and 7210 SAS-R6 and 7210 SAS-R12 equipped with IMM-b cards, the CBS and MBS values for the queues are configurable for the service egress and network port queues. The CBS and MBS is set to default values that address the specific FC needs to maintain differential treatment.
On the 7210 SAS-T (network and access-uplink mode), the node can be operated with either a per-port or per-node MBS pool. The decommissioning feature is supported in the per-port MBS pool mode, which increases the per-port MBS pool by taking away packet buffers from other ports. In this case, the maximum MBS per queue, assuming no other queue has traffic on that port, depends on the user configuration. For example, assuming one port is decommissioned and its buffers are allocated to port 1/1/1, the maximum MBS per queue on port 1/1/1, assuming no other queues have any traffic, is 93 Kbytes. The show pools port-id network-egress, show pools port-id access-egress, and show pools port-id access-uplink-egress CLI commands display the values in use depending on the port mode (network, access, and access-uplink).
The following table lists the default CBS and MBS values for the 7210 SAS platforms.
| Platform | CBS (KBytes) | MBS (KBytes) | ||
|---|---|---|---|---|
| Network queue and access-uplink queue | Access queue | Network queue and access-uplink queue | Access queue | |
7210 SAS-T (MBS Pool = Port) 1 |
3.375 |
3.375 |
33 2 |
33 2 |
1.68 |
1.68 |
1458 4 |
1458 4 |
|
7210 SAS-Mxp |
128 |
10 |
256 |
64 |
7210 SAS-R6 (IMM-b) |
128 |
10 |
256 |
64 |
7210 SAS-R12 (IMM-b) |
128 |
10 |
256 |
64 |
7210 SAS-R6 IMM-c 5 |
1.6 |
1.6 |
1255 6 |
1255 6 |
7210 SAS-R12 IMM-c 5 |
1.6 |
1.6 |
1150 6 |
1150 6 |
7210 SAS-Sx/S 1/10GE 24-port variant 5 |
1.6 |
1.6 |
905 6 |
905 6 |
7210 SAS-Sx/S 1/10GE 48-port variant 5 |
1.6 |
1.6 |
698.34 6 |
698.34 6 |
7210 SAS-Sx 10/100GE 5 |
1.6 |
1.6 |
4158.4 6 |
4158.4 6 |
7210 SAS-Sx/S 1/10GE (standalone-VC) 5 |
1.6 |
1.6 |
712.7 6 |
712.7 6 |