nanog mailing list archives
Re: Fiber only in DataCenters?
From: Matthew Kaufman <matthew () matthew at>
Date: Thu, 20 Dec 2012 15:20:18 -0800
On 12/17/2012 9:22 AM, joel jaeggli wrote:
If the facility is big enough the utility of twisted pair becomes quite limited, both due to distance and differing electrical potential, multibuilding campuses in particular make this is a nonstarter.
For twisted-pair Ethernet: Distance yes. Differing electrical potential no. It is a balanced pair, transformer coupled at both ends. As long as AC common-mode pickup doesn't saturate the transformer core, it just works.
In one facility I'm in, I'm over 300 meters from each of the MMRs, with the results that the OOB for the serial console server for out equipment located out there in the MMR's being on serial over fiber transceivers connected by om4 multimode.
RS232 serial is another story. Here the potential difference between the ends is a big deal. (I've even seen burned-through PC boards from what happens when pin 7 has 220 VAC flowing from one device to the other) But you can just run Ethernet out to the console server and plug it in next to the gear with the serial port to fix this.
Matthew Kaufman
Current thread:
- Fiber only in DataCenters? James Wininger (Dec 17)
- Re: Fiber only in DataCenters? Andrew Latham (Dec 17)
- Re: Fiber only in DataCenters? Owen DeLong (Dec 17)
- Re: Fiber only in DataCenters? Walter Keen (Dec 17)
- Re: Fiber only in DataCenters? Isabel Dias (Dec 17)
- Re: Fiber only in DataCenters? joel jaeggli (Dec 17)
- Re: Fiber only in DataCenters? Matthew Kaufman (Dec 21)
- Re: Fiber only in DataCenters? George Herbert (Dec 21)
- Re: Fiber only in DataCenters? Owen DeLong (Dec 21)
- Re: Fiber only in DataCenters? George Herbert (Dec 21)
- Fun With Plasma (Re: Fiber only in DataCenters?) Jay Ashworth (Dec 24)
- Re: Fiber only in DataCenters? Jay Ashworth (Dec 24)
- Re: Fiber only in DataCenters? Matthew Kaufman (Dec 21)
- RE: Fiber only in DataCenters? Naslund, Steve (Dec 21)
- Re: Fiber only in DataCenters? Andrew Latham (Dec 17)
- Re: Fiber only in DataCenters? Michel de Nostredame (Dec 18)