Customer inquire about the relation between Packet Length and throughput
As formula can not be type in case description, please refer to attachment for detail.
Frame size Versus Throughput
1． Throughput (Thp)
The amount of data transferred in one direction over a link divided by the time taken to transfer it, usually expressed in bits or bytes per second.
2． Transmission Efficiency (Ev)
At real scenario, there are 64-bits preamble and 96-bits frame gap, which total 20Bytes, between the standard Ethernet frames. We assume Ethernet frame length as PktLen, then Transmission Efficiency (Ev) defined as below:
In accordingly, we got below Transmission Efficiency:
Frame (Byte) Transmission Efficiency
Obviously, the bigger frame size, the higher Transmission Efficiency.
3． Encapsulation Efficiency
As we know, packet will be encapsulated to SDH frame while transmitted over SDH network, which could adhibit Encapsulation Efficiency. For example, GFP encapsulation, actually we use this kind of encapsulation almost, will add extra 8 Bytes overhead during encapsulation. Thereby, we define Encapsulation Efficiency (EvB) as below:
Then the GFP SDH side transmission capacity Bandwidth is:
Then Throughput was defined as:
Thereby, if PktLen1>PktLen2, then Thp1<Thp2
5． How to calculate ?
VC12=34Byte/frame * 8000frame/s=34*8*8000 bit/s=2.176 Mb/s
VC3=756Byte/frame * 8000frame/s=756*8*8000 bit/s=48.384 Mb/s
VC4=2340Byte/frame * 8000frame/s=2340*8*8000 bit/s=149.760 Mb/s
Remark: All above data is the most idea data, which consider Card work with very well performance and forward all the packets without any limitation.