- Why I did it
Support DSCP remapping in dual ToR topo on T0 switch for SKU Mellanox-SN4600c-C64, Mellanox-SN4600c-D48C40, Mellanox-SN2700, Mellanox-SN2700-D48C8.
- How I did it
Regarding buffer settings, originally, there are two lossless PGs and queues 3, 4. In dual ToR scenario, the lossless traffic from the leaf switch to the uplink of the ToR switch can be bounced back.
To avoid PFC deadlock, we need to map the bounce-back lossless traffic to different PGs and queues. Therefore, 2 additional lossless PGs and queues are allocated on uplink ports on ToR switches.
On uplink ports, map DSCP 2/6 to TC 2/6 respectively
On downlink ports, both DSCP 2/6 are still mapped to TC 1
Buffer adjusted according to the ports information:
Mellanox-SN4600c-C64:
56 downlinks 50G + 8 uplinks 100G
Mellanox-SN4600c-D48C40, Mellanox-SN2700, Mellanox-SN2700-D48C8:
24 downlinks 50G + 8 uplinks 100G
- How to verify it
Unit test.
Signed-off-by: Stephen Sun <stephens@nvidia.com>
Calculate pool size in t1 as 24 * downlink port + 8 * uplink port
- Take both port and peer MTU into account when calculating headroom
- Worst case factor is decreased to 50%
- Mellanox-SN2700-C28D8 t0, assume 48 * 50G/5m + 8 * 100G/40m ports
- Mellanox-SN2700 (C32)
- t0: 16 * 100G/5m + 16 * 100G/40m
- t1: 16 * 100G/40m + 16 * 100G/300m
Signed-off-by: Stephen Sun <stephens@mellanox.com>
Co-authored-by: Stephen Sun <stephens@mellanox.com>
