Why does Ethernet us a standard of 1500 as an MTU?

FrankGuthrie

Why did they decided that 1500 bytes is the norm? You can use jumbo frames up to 9000 something bytes, but I wondering back in the day why they choose 1500 bytes? Anybody know the answer?

Nans

Well thats how the frames are developed . Only to fit 1500 bytes as the payload size which is teh Maximum Transmission Unit (MTU). And if you ask why only that fixed size thats what the developers thought might be easy to handle for fast processing and some thing like that.

I just said what i thought.. there are experts please correct me if I am wrong

Regards

beads

Because they fit nicely in 4k buffers. Otherwise you end up with jumbo frames that used to cause buffer overflows so regularly that the phrase Denial of Service or DoS was needed. Now imagine a 1Gig packet - ten thousand times a second.

james43026

It's a matter of efficiency, sending lots of frames significantly smaller than 1500 bytes is inefficient because there is a large amount of overhead due to processing all of the header info on each frame. Anything significantly larger than 1500 bytes can be inefficient because a link will be saturated with data for longer for just a single packet increasing latency, this can cause delays that are undesireable such as VOIP traffic which is extremely time sensitive, and must avoid all latency, this latency could cause jitter, or just silence as the packets wouldn't be received in time to actually be used. And just in case you were wondering, the minimum size of 64 bytes for a frame, comes from the fact that if a collision is going to occur on a link, then it will happen almost always happen in the first 64 bytes, if you see collisions outside of the first 64 bytes of a frame, it almost always indicates a duplex mis-match.

Keep in mind there are networks that use jumbo packets, which are packets that are much larger than the standard MTU of 1500 bytes.

FrankGuthrie

Thanks James.