Use Of Aggregate Control Buffer Pools - Alcatel-Lucent 7450 Quality Of Service Manual

Use of Aggregate Control Buffer Pools

The aggregate control buffer pools are separated into two sets. The first 16 pools (0 through
15) are used by the provisioned group (group P) port class pools. The second 16 pools (16
through 31) are used by the system group (group S) port class pools.
The first 8 (0 through 7) are used as class based pools. Pool 0 is used by scheduling class 1
(0 internally) and pool 7 is used by scheduling class 8. Agg-Pool-Ptr-1 for port class pools 0,
8, 16, 24, 32, 40, 48, 56, 64 and 72 (all port call pools associated with queues with queue-id
1) is set to aggregate control pool 0. This ensures that all provisioned queues in scheduling
class 1 are limited based on the amount of buffering for class 1 on their port and also the total
buffers used by the class is limited for the XMA or MDA. If either of the pools is exhausted,
the queue will not receive a buffer. In like manner, Agg-Pool-Ptr-1 for all port class pools 1,
9, 17, 25, 33, 41, 49, 57, 65 and 73 is set to pool 1. This is true up to port class pools 7, 15,
23, 31, 39, 47, 55, 63, 71 and 79 having Agg-Pool-Ptr-1 set to pool 7.
The second 8 aggregate control buffer pools (8 through 15) are used as provisioned root
pools. The purpose of the root pools is to allow the class pools to be oversubscribed without
the possibility of the provisioned buffer usage stealing buffers from the system reserved
buffers. Before sizing the provisioned root pools, a portion of the total buffer space is set aside
for system purposes. The remaining buffers are divided between the provisioned root pools
based on a weight parameter in each root pool. The weights may be set between 0 and 100.
A value of zero indicates that a specific provisioned root pool will not receive buffers (pool
size will be 0). Because root pools cannot be oversubscribed, they provide a protection
mechanism for higher level pools. The number of root pools in use is dependent on the
HSMDA pool policy applied to the XMA or MDA (ingress and egress are controlled by
independent policies). The aggregate control class pools are associated with the root pools
through the policy as well.
Quality of Service Guide
Figure 48: Aggregate Control Buffer Pools Table
0 Buffers-Available (21bits)
1 Buffers-Available (21bits)
2 Buffers-Available (21bits)
3 Buffers-Available (21bits)
4 Buffers-Available (21bits)
31 Buffers-Available (21bits)
Figure 49 represents the buffer pool hierarchy.
High Scale Ethernet MDA Capabilities
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