Hi Sheldon,
You wouldn’t need to use the rate-mode dedicated command on the N7K-F248XP-25 as there’s no over-subscription between the ports on the module and the switch fabric. As per the Cisco Nexus 7000 F2-Series 48-Port 1 and 10 Gigabit Ethernet Module Data Sheet “the module delivers 720 million packets per second (mpps) of distributed Layer 2 and Layer 3 forwarding and up to 480 Gbps of data throughput.”
As there are 48 10GE ports the maximum “port facing” bandwidth would be 480 Gbps, and so no over-subscription. If you have no over-subscription to the switch fabric, there's no requirement to use rate-mode dedicated.
The rate-mode dedicated command is intended for older modules such as the N7K-M132XP-12 which are over-subscribed modules. This module has 80 Gbps to the switch fabric, but presents a possible 320 Gbps i.e., 4:1 over-subscription.
As per the Rate Mode section of the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide:
“On a 32-port 10-Gigabit Ethernet module, each set of four ports can handle 10 gigabits per second (Gb/s) of bandwidth. You can use the rate-mode parameter to dedicate that bandwidth to the first port in the set of four ports or share the bandwidth across all four ports.”
Using this command disables three of the four ports in a group, meaning the module only uses eight of the 32 ports, resulting in a maximum 80 Gbps port facing bandwidth, and so removes over-subscription.
The following picture is the architecture of the N7K-M132XP-12 module and hopefully makes understanding the above a little easier.
Regards
