Ethernet switches use the memory buffering technique to temporarily store frames in memory before forwarding them out the destination ports. There are two types of memory buffering techniques used by Ethernet switches: port-based memory buffering and shared memory buffering. In this article, we will discuss the features of port-based memory buffering technique. So, let’s begin;
What is a memory buffer?
As you may know, the speed of a processor is always higher than that of connected devices and peripherals. For this reason, the processor sits idle while it waits for other devices and peripherals. Buffer memory is used to take advantage of these idolized processor timings. This idea was introduced to avoid data congestion from incoming and outgoing transfer ports.
In computing and technological terms, the buffer is a storage region that stores temporary memory. The buffer memory contains data stored for a short period of time. Especially in the random access memory (RAM) of the computer. Buffer memory is a part of computer memory that works as a temporary storage place for data. This temporary data is sent or received from external devices and peripherals. HDD (hard disk drive), keyboard, printers and other peripheral devices act as the source for sending and receiving this temporary data.
What is port based memory buffering?
In port-based buffering, frames are stored in queues and the port switching process is completed using the port’s buffered memory. The queues used in port-based memory buffering are connected to specific incoming ports. Until then, the forward port buffering switch can provide each Ethernet port with high-speed memory to buffer frames. Frames can be successfully transmitted to the output port from the queues. And this is only possible when all the frames in the buffered queue have been transmitted successfully.
The main drawback of port-based memory buffering is that frames can be dropped when the port runs out of buffer. Also, a single frame can delay the transmission of the frame while the destination ports are busy. This delay will occur even while frames are being transmitted to open destination ports.
What is a feature of port-based memory buffering?
As stated before, Ethernet switches use buffering techniques to store frames for transmission. And port-based buffering techniques rely on queues bound to specific ports to store memory frames. There are a few features seen in port-based memory bufferings. These features will help you identify port-based memory buffering. These are the characteristics of a port-based memory buffering;
- Memory frames are stored in the queue that is tied to specific incoming and outgoing ports before transmitting.
- All frames are stored in a common memory buffer for transmission to ports.
- A single memory buffer is shared among all existing ports on a switch.
- The memory frames are dynamically bound to the destination ports before starting the transmission process.
- A single frame can delay the transmission of the frame while the destination ports are busy.
- Frames can be dropped while the port is running out of buffer.
Frequently asked questions (FAQ)
What is the minimum and maximum size of an Ethernet frame?
The minimum size of an Ethernet frame is 64 bytes, while the maximum size of an Ethernet frame is 1518 bytes. The size of most Ethernet frames is between 64 and 1518 bytes.
What is the purpose of frame buffers on an Ethernet switch?
Before transmission, frame buffers perform checksum values and hold traffic to relieve congestion on the Ethernet switch network. Also, the Ethernet switch required a large frame buffer to prevent data loss, which is beneficial for incoming traffic from the switches. This is the main purpose of the frame buffers in the Ethernet switch.
When should I use shared memory buffering instead of port-based buffering?
Shared memory has the ability to store larger frames with minimal dropped frames, which is quite important for different data rates from different data ports. Therefore, you should use shared memory buffering instead of port-based buffering while using asymmetric switching. And you know that asymmetric switching provides different data rates from different data ports.
At this point, you know enough about the common features of the port-based memory buffering technique. This technique is suitable for Ethernet switches that use specific ports to transmit data. Well until today, have a great day.