Ethernet speed connection 10/100 on PCB 19.5
#4
Mike, I might be wrong, but reading the quote, it looks like someone was having a problem and asking for help.

In the *old* days this was true in the case of HUBS. There data was received on one port and sent out to all the other ports causing slowdowns.

Todays new modern switches works totally different. Since switches operates at the Data Link Layer (layer 2), data received on one port is only sent out to one port by means of MAC address learning inside the switch resulting in wire speed operation.

"All switches contain some high-speed buffer memory in which a frame is stored, however briefly, before being forwarded onto another port or ports of the switch. This mechanism is known as store-and-forward switching. All IEEE 802.1D-compliant switches operate in store-and-forward mode, in which the packet is fully received on a port and placed into high-speed port buffer memory (stored) before being forwarded. A larger amount of buffer memory allows a bridge to handle longer streams of back-to-back frames, giving the switch improved performance in the presence of bursts of traffic on the LAN. A common switch design includes a pool of high-speed buffer memory that can be dynamically allocated to individual switch ports as needed."

My ISP router have 4 x 1Gb ports, but I don't plug any 'slow' devices into those ports. Rather, I have a 8 port managed Layer 2 Cisco switch (2960G) with a 1Gb uplink connected to the router. I use the switch to control traffic flow from the 'slow' devices. I regularly monitor the switch performance and have not seen any packet drops, buffer overload or latency issues.

On the other hand, these ISP routers are not commercial grade and could possibly cause network issues and packet drops. The reason why they are not used in Data Centers Dodgy but rather $$$$ routers.

Also there is a difference in performance between a $10 and $100 switch.

Dries
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RE: Ethernet speed connection 10/100 on PCB 19.5 - by dupreezd - 2020-02-29, 21:54

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