Port Buffer

[prashanma]

What is Port buffer in switch or routing environment ?

[Joseph W. Doherty]

It's a storage location for frame and/or packets that cannot be immediately forwarded or processed on a port.

Port buffers are often also known as port queues. Such queues might be just implemented as a simple global FIFO queue or they might support "fancy" queue management. That said, when referred to as buffers, very often they are just managed FIFO.

[prashanma]

Thanx Joseph for explanation,

So packet buffer memory & port buffer memory are the same or two different things ?
Can we take the packet buffer memory value as port buffer value ?

[Joseph W. Doherty · Accepted solution]

"So packet buffer memory & port buffer memory are the same or two different things ? "

Sometimes yes, sometimes no. Buffers is an "overloaded" term.

On routers, buffers refers to main RAM memory. Port buffers might be RAM in the interface card itself or main RAM allocated to interfaces accounts for differently than RAM allocated/managed as part of IOS.

[prashanma]

So Cisco 2960L packet buffer memory is 2MB, what will be port buffer memory ? it will be 2MB or 2MB/24

[Joseph W. Doherty]

That RAM is used by all the ports. Generally on 2960 series switches, the default is some of that buffer RAM is reserved per port, other RAM is dynamically allocated per port, as needed. If you enable QoS, you can modify how buffer RAM is reserved and dynamically allocated per port.