I need some clarity on:
- What exactly throughput and capacity means of any switch (assume it has 24 1Gi and 2 10Gi ports) .
- I have referred this link: https://supportforums.cisco.com/t5/lan-switching-and-routing/throughput-mpps-switching-capacity-gbps-relation/td-p/2176262
Here I unable to understand the below text :
Your particular switch has 24 gig ports and two 10g ports, so for maximum performance, it needs 44 * 2 (for duplex) = 88 Gbps for its fabric.
Minimum size Ethernet requires 1.488 Mpps per Gbps, so 44 * 1.488 = 65.472 Mpps.
My question is :
Question 1: how the maximum performance it needs 44 * 2 (for duplex) = 88 Gbps for its fabric I am thinking it should be 44 Gbps for both half/full duplex --can you help me with this ?
Question 2: Minimum size Ethernet requires 1.488 Mpps per Gbps, so 44 * 1.488 = 65.472 Mpps". I did not understand this formula, what is 1.488 and mpps mean. Can you please explain this ?
I know minimum ethernet header should be 64 bytes .
Thank you !!
I can attempt to answer your question, to the best of my knowledge we have throughput of the device which has dependent on the core I/O bandwidth of the ASIC.
It doesn’t necessarily mean that if a switch has x number of ports of type 1Gig and the throughput will be 2*xGig.
Forwarding capacity refers to the lower packet sizes (generally 128 byte) uni directional throughput.
you can refer the data sheet of the following, the device has 64*100Gig ports and the ASIC also capable of supporting 6.4T, Bidirectional throughput is 12.8Tbps, forwarding capacity will be 4.2Bpps.
I need to understand why Forwarding capacity convention is Bpps and where as Bidirectional throughput is Tbps
This sounds correct to me. Keep in mind that when you use full duplex, it means you can send and receive traffic at the same time. For example, with a gigabit interface, you can receive up to 1 Gbit of traffic and send 1 Gbit of traffic at the same time.
PPS stands for packets per second. Here’s how they came up with this number:
A gigabit interface sends 1000000000 bits/second. In bytes, that’s 1000000000 / 8 = 125000000 bytes/second.
For these calculations, they use a minimum Ethernet frame length of 64 bytes, an 8-byte frame header, and an 12-byte frame gap.
64 + 8 + 12 = 84
125000000 / 84 = 1488095
In other words, the switch needs to be able to forward 1488095 packets per second (1.488 million packets per second) to hit the gigabit speed.
Does this help?