OmniSwitch OS6860/OS6900/OS10K Troubleshooting Guide Part No.032996-00 Rev.A
AOS Release 7.X and 8.X January 2015
Alcatel-Lucent Page 63 of 148
10. Troubleshooting QoS
Checklist
Make sure that the "log" keyword in "policy rule" is realy needed - presense of this keyword is
increasing TCAM usage by 1 entry per rule
Use masks for MAC and IP addresses wherever possible
Prefer actions with "maximum bandwidth" than "cir"
Use manually optimized network group in place of build in "Switch"
Specify source ports where applicable
Summary of the commands in this chapter is listed here:
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show configuration snapshot vfc
show qos slice
show qos slice <slot/port>
tail -f vfc1.log
debug qos internal "slot 1 list 255 verbose"
d chg fp_port_field_sel
d chg fp_tcam
d chg fp_policy_table
d chg fp_meter_table
d chg fp_counter_table
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10.1. Introduction
Trident hardware limitations
Number of meters and counters supported in the Trident's ICAP is 2048. Each meter bucket size can be
programmed from 512B to 64KB. The granularity for the meter ranges from 8Kbps to 10Gbps. These 2K
meters are globally located outside the IFP and grouped into 4 meter pools. Each meter pool has 256 meter
pairs (containing odd and even meter).
Each port supports the egress shaping by using the leaky bucket. The meter bucket size can be programmed
from 256B to 32KB. The granularity for the meter ranges from 8 Kbps to 10 Gbps.
Trident slices don't support double wide mode. It will support only the slice pairing mode for all the slices. In
7.1.1.R01, double wide mode is used for CPU-Q slice. Here CPU-Q slice entries are configured in single slice
(7) in single wide mode.
Trident doesn't support WRED statistics for different colors at queue level. It will support drop statistics for
each color at the port level.
The BCM56840Ax Errata says that in 640G device, there can be inaccuracies in egress port shaping
mechanism. Accuracy of shaping can degrade with a function of the packet size number of active ports and
specified shaping rate.In worst case this shaping rate can degrade by ~16%. However BCM56840 480G is
unaffected by this issue. So Egress shaping in 640G device in full line rate can be unpredictable. From the
software side we can create a set of Unit Tested result and share it but test has to fine tune the actual behavior.
OS6900 Platform uses Trident in the data path which supports 10 slices. In 10 slices, first 4 slices contain 128
entries per slice and the remaining 6 slices have 256 entries per slice, resulting in total of 2048 IFP entries.
Reserved slices
OS6860
Helix4 has 16 slices of 256 entries each:
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