back to article Juniper prepping for a 400 Gbps Ethernet world

With vendors gearing up for the transition from 100 Gbps to 400 Gbps Ethernet in bit-barns, The Register's networking desk spoke to Juniper Networks' Manoj Leelanivas about what to expect. Leelanivas, EVP and chief product officer at the Gin Palace, said 400 Gbps take-up will likely be quite different to how 100 Gbps adoption …

  1. Christian Berger Silver badge

    "4K" kinda probably not going to need that much data

    I mean, yes higher Ethernet speeds will most likely be needed, even if it just means that your datacenter can be packet more efficiently over time. If you can replace 4 servers with each having a 10G connection with one with a single 40G that will mean you can do much higher densities.

    However "4K" is just another video resolution. Since the advent of block based video codecs the resulting bitrate does not grow linearly with the number of pixels you want to transmit. You can see that with typical TV transmissions. HDTV roughly requires 4 times as many pixels per second than SD, however while SD typically runs at 4-10 Mbps, HD rarely is done at more than 13 Mbps on TV. It's just that there is not that much more relevant information in the picture to be encoded. "4K" will likely continue the trend and I'm guessing it'll be transmitted at around 15-20 Mbps. Better codecs will help with that, too.

    So in short there are probably many reasons for 400Gpbs, but 4K probably won't really be among them.

  2. A Non e-mouse Silver badge


    My random musing is: How do you make the chips that can operate at 400GHz (and over) to drive the optics?

    1. Anonymous Coward
      Anonymous Coward

      Re: Speed

      They don't, just like 40 and 100Gbit/s don't. 40gbit runs at 4 x 10gbit channels (4 optics) 100gbit runs at 4 x 28gbit/s (first attempts were 10 x 10gbit, with the 10gbit channels being a dead-end now). This will now probably be using the 4 x 100gbit channel.

      These channels will then have an encoding scheme such as QPSK (there are higher ones too), with this each transmitted symbol represents 2 bits.

  3. IJD

    400GE will either use 4 intensity-modulated channels of 100G PAM4 (shortest reach), 8 channels of 50G PAM4 (medium reach), or a single channel of 400G QAM16 coherent optics (longest reach).

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