PFC

[danial.jalil]

What is the difference between switch with PFC capabilities and switch without it? because apparently the end device sends Pause frames right?

[AFROJ AHMAD]

Hi Danial,

PFC allows you to apply pause functionality to specific classes of traffic. this is the Major role of PFC.

Priority Flow Control

The priority flow control (PFC) capability allows you to apply pause functionality to specific classes of traffic. PFC decides whether to apply pause based on the IEEE 802.1p CoS value. When the switch enables PFC, it configures the connected adapter to apply the pause functionality to packets with specific CoS values.

By default, the switch negotiates to enable the PFC capability. If the negotiation succeeds, PFC is enabled and link-level flow control remains disabled (regardless of its configuration settings).

If the PFC negotiation fails, you can either force PFC to be enabled on the interface or you can enable IEEE 802.x link-level flow control.

Device can send pause frame for N number of reasons :(

for e.g interface connecting to a server  and server is sending traffic more than the link capacity of the switch

Thanks-

Afroz

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