7210 SAS-D provides an option to use either 2 slope per queue or 3 slopes per queue. This can be configured using the CLI command config>system>qos>no use-wred-slopes. The option to use only 2 WRED slopes per queue (port egress queues), allows differentiating in-profile and out-of-profile traffic flows. The option to use 3 WRED slopes per queues allows differentiating in-profile TCP traffic, out-of-profile TCP traffic and non-TCP traffic (both in and out-profile use a single slope). The slope does not get enabled by default. To maintain backward compatibility, by default the system uses 3 slopes option and user has to change it explicitly to use 2 slopes (if they need).
The following table compares the WRED slope used for different traffic flows with 2 slopes or 3 slopes per queue.
Slopes |
TCP-non-TCP slope option (uses 3 WRED slopes per queue) |
High-low slope option (uses 2 WRED slopes per queue) |
|---|---|---|
SAP Ingress TCP/IP traffic (Number of VLAN tags <=2) |
High-priority TCP slope or low-priority TCP slope, based on packet profile |
High-priority or low-priority slope, based on packet profile |
SAP Ingress non-TCP traffic (Number of VLAN tags does not matter) |
Non-TCP slope - No in/out profile differentiation |
High-priority or low-priority slope, based on packet profile |
SAP Ingress TCP/IP traffic (Number of VLAN tags>2) |
Non-TCP slope - No in/out profile differentiation |
High-priority or low-priority slope, based on packet profile |