4 ms·
“Line rate” is not “fill the link with TCP”. Line rate is “fill the link with 84 octet (including all overhead) frames.” For 100M Ethernet this requires 148,8
by gonzo 2y ago
“Line rate” is not “fill the link with TCP”. Line rate is “fill the link with 84 octet (including all overhead) frames.”
For 100M Ethernet this requires 148,809 packets per second.
Edit: for 1538 octet frames, one need only process 8,127 packets per second.
- dark-star 2y ago"Line rate" is "fill the 100Mbit link with 100 million bits each second". Of course the overhead is included in that, since the overhead also goes over the wire
- Hikikomori 2y agoSmallest packet line rate is usually the definition network engineers use when discussing performance of devices.
- gbil 2y agoI'm many years away from such topics but I don't remember this being the case, moreover specs for net equipment was (is) on pps with the details stating usually 2-3 packet size categories. I'm interested on some reference on what you wrote
- Hikikomori 2y agohttps://www.fmad.io/blog/what-is-10g-line-rate https://www.fmad.io/blog/what-is-10g-line-rate As the article calls it, the gold standard. If a device is capable of forwarding/switching packets at the smallest packet size line rate on all interfaces at the same time you don't have to think too much about its performance when designing your network. Haven't worked much with hardware for a few years but it was common that Cisco switches were not capable of this.
- Dylan16807 2y agoGold standard sure, but that doesn't make it the definition of line rate.
- nsteel 2y agoVendors I've seen usually use one of a few "standard" packet size mixes e.g. imix. Nobody uses smallest size frames because nobody can hit their headline perf numbers for that, and it's not representative of real-world usage anyway. https://en.m.wikipedia.org/wiki/Internet_Mix https://en.m.wikipedia.org/wiki/Internet_Mix
- Hikikomori 2y agoI think this applies more to firewalls used for simple internet connections than switches/routers.
- nsteel 2y agoI was specifically talking about enterprise/core routers where the packet processing can be non-trivial and small frames hurt performance.
- Hikikomori 2y agoWhat core routers uses imix?
- nsteel 2y agoNot sure what you mean, but an example of using imix to measure perf of a core router is Cisco 8000 series https://miercom.com/wp-content/uploads/2024/02/Performance-Validation-for-Cisco-8000-Series-DR230428E-13Feb2024-.pdf https://miercom.com/wp-content/uploads/2024/02/Performance-V...
- Hikikomori 2y agoThat 8200 for example is capable of line rate at the smallest packet size so that imix marketing is kinda useless. When evaluating these kinds of devices this is what matters. IMIX makes sense on devices that are not capable of small packet line rate like firewalls where bandwidth is much more costly and need to be sized appropriately.
- gonzo 2y agoThis is a lazy definition and won’t get you past “Go” when making network equipment. Why not use 9000 byte “Jumbo” frames? You’ll only need to process 1,383 packets per second to fill the link!