Dell PowerSwitch S4820T 9.50.1 Configuration Guide for the S4820T System - Page 739

class dynamic dotp or trust dot1p. When priority-tagged frames ingress a tagged port, the frames are dropped because, for a tagged port, the default VLAN is 0. Dell Networking OS Behavior: Hybrid ports can receive untagged, tagged, and priority tagged frames. The rate metering calculation might be inaccurate for untagged ports because an internal assumption is made that all frames are treated as tagged. Internally, the ASIC adds a 4-bytes tag to received untagged frames. Though these 4-bytes are not part of the untagged frame received on the wire, they are included in the rate metering calculation resulting in metering inaccuracy. Configuring Port-Based Rate Policing If the interface is a member of a VLAN, you may specify the VLAN for which ingress packets are policed. • Rate policing ingress traffic on an interface. INTERFACE mode rate police Example of the rate police Command Dell#config t Dell(conf)#interface tengigabitethernet 1/0 Dell(conf-if)#rate police 100 40 peak 150 50 Dell(conf-if)#end Dell# Configuring Port-Based Rate Shaping Configuring port-based rate limiting is supported on the S4820T platform. Dell Networking OS Behavior: Rate shaping is effectively rate limiting because of its smaller buffer size. Rate shaping on tagged ports is slightly greater than the configured rate and rate shaping on untagged ports is slightly less than configured rate. Rate shaping buffers, rather than drops, traffic exceeding the specified rate until the buffer is exhausted. If any stream exceeds the configured bandwidth on a continuous basis, it can consume all of the buffer space that is allocated to the port. • Apply rate shaping to outgoing traffic on a port. INTERFACE mode rate shape • Apply rate shaping to a queue. QoS Policy mode rate-shape Example of rate shape Command Dell#config Dell(conf)#interface tengigabitethernet 1/0 Dell(conf-if)#rate shape 500 50 Dell(conf-if)#end Dell# Quality of Service (QoS) 739