I have a 10G XPF+ optical cable with market updates from a stock exchange. This cable goes into a switch, which then mirrors every packet to a couple of computers over two ports. The problem with using a switch for mirroring is that there is latency overhead, even with a pass-through switch (~200ns).

Are there "optical" solutions (I'm thinking of a beam splitter of some sort) which would allow for close to zero latency 10G mirroring?

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    You HFAT guys are so crazy. – Tom O'Connor Sep 9 '13 at 12:20
  • There is a solution... I know of a couple of devices that would help you bypass the switch. What devices are in use here? Arista? – ewwhite Oct 25 '13 at 22:31
  • @Randomblue I'm under NDA... but I'll update as soon as I can speak about it. – ewwhite Oct 25 '13 at 22:46
  • Okay. I can talk about it. See my answer. – ewwhite Oct 26 '13 at 0:22

My old firm manufactures a port replicator that solves the problem you're having. It's a Layer 1 device that can take a market data feed and multiplex to a number of ports at <10ns latencies. This bypasses the Arista switch for one-way market data consumption.

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Are there "optical" solutions (I'm thinking of a beam splitter of some sort) which would allow for essentially zero latency 10G multicast?


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    Ye' cannae' break the laws of Physics, Jim! – tombull89 Sep 9 '13 at 12:09
  • "beam splitter" effectively splits the photon stream, so only half the photons goes each way. this possibly breaks the signal sent. Amaright ? – mveroone Sep 9 '13 at 12:18
  • @Randomblue - certainly prismatic optical networking adds VERY little, not zero, but very little latency to the equation - the issue here though is that you still need to turn the data into regular ethernet and there's no real way of doing that without some form of switch involved - which inherently brings latency. Bay Networking used to sell a range called ONS that was designed for just this thing but I think that line got dropped or sold-on when they went bust - perhaps you could look around as I'm sure there are better products to use than 'regular' switches. Good luck. – Chopper3 Sep 9 '13 at 12:22
  • @Randomblue I'm not sure I see your point - even light has a finite speed. – Dan Sep 9 '13 at 12:22
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    @Randomblue If you come into chat, we've started compiling a list of people who've asked Chopper3 direct questions and then disappeared. I'd suggest locking your doors. – Dan Nov 8 '13 at 11:32

Yes, port mirroring is possible using network taps, with latency an order of magnitude less than a using a switch. There is a video demonstration here.

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