Angled Polish Connectors and DWDM
dear peoples of NANOG, I've always held the -- possibly completely false -- notion that angled connectors (APC) were not idea for fiber spans carrying multiple dense/DWDM wavelengths. However, after copious amounts of googling and duckduckgo'ing I cannot find an opinion or tech note one way or the other. Are there situations when angled connectors are not to be used? Are they 'safe' or even recommended for any kind of DWDM application? I know they're not meant for mating directly with optics, but for panels, x-conns, and distribution frames...? I have this sinking feeling I've been misunderstanding angled connectors all these years. cluebats are appreciated. please be gentle. thanks, aaron
Re: Angled Polish Connectors and DWDM
Hi Aaron, Are there situations when angled connectors are not to be used? Are they 'safe' or even recommended for any kind of DWDM application? To my knowledge APC is always better than PC connectors. APC are used to eliminate back reflections. Due to the angled connector reflections are sent mostly towards the cladding and not the core and therefore. The effecs of back reflections are great. Read this http://documents.exfo.com/appnotes/anote044-ang.pdf I can not see why APC connectors are not to be used, even with DWDM. The only problem with APC is that there are different kinds of angles (8 degrees and 9 degrees) and polishments of the tip. When using the wrong connectors (for example a 8 degrees against a 9 degrees in a coupler) you will introduce more loss. This would be the reasons why some people fear to use APC. regards, Igor
Re: Angled Polish Connectors and DWDM
On Sun, 30 Sep 2012, Igor Ybema wrote: To my knowledge APC is always better than PC connectors. APC are used to eliminate back reflections. Due to the angled connector reflections are sent mostly towards the cladding and not the core and therefore. I've been told this is very important in HFC solutions (hybrid fibre coax). Operationally though, having APC is a hassle. I know of companies who mandated APC for a few years for all installations, but then reverted back to UPC due to operational problems (people putting UPC cables into APC ODFs etc). So while APC might be technically superior when properly installed, it's not always better when looking at the whole system. -- Mikael Abrahamssonemail: swm...@swm.pp.se
Re: Angled Polish Connectors and DWDM
On Sun, Sep 30, 2012 at 11:52 AM, Igor Ybema i...@ergens.org wrote: Hi Aaron, Are there situations when angled connectors are not to be used? Are they 'safe' or even recommended for any kind of DWDM application? To my knowledge APC is always better than PC connectors. APC are used to eliminate back reflections. Due to the angled connector reflections are sent mostly towards the cladding and not the core and therefore. Indeed. I have always held the idea that APC connectors induced greater chromatic and/or polarization mode dispersion -- yet can't find any resources that claim so, nor does that fit in with my working mental model of how light propagates. Just something I picked up during the hellish days of trying to deploy 10GbE before it was cool; now I'd like to know if it is grounded in any science (-: Thanks aaron
RE: need help about 40G
Hi Deric, On the part of 40G, there is a clear financial benefit instead of moving currently towards 100G. If you don't need 100G yet, there is a lot of money to be saved by skipping first generation 100G. 40G ports will only set you back around 1500 US$ per port. Optics are also quite cheap and because of that, it is a nice solution. As already mentioned by Adam in his reply. Extreme Networks has a device (the BD X8) that can fit 192 - 40G ports in 14.5U (or 1/3) rack space. These can also be used as 768 10G ports, if you split the 40G into 4*10G. Which you can by just putting other cabling to the optic. If you don't require such a large quantity of ports, there are also smaller (1U switches) with have 4*40G option boards, like the X670V from Extreme. These boxes are not expensive, stable and provide a great price to port density ratio. Also something which is very interesting, these boxes have both a very low latency, which makes them ideal for storage, cloud and trading scenarios. There are some tests reports you can find online if you are not only looking for 40G but specifically in combination with very low latency. I personally haven't used the Mellanox 40G nics yet, but I have been told that these have been tested by other customers and work like a charm with the Extreme kit. If you have more specific questions, please let me know (can also off-list). Regards, Erik Bais
Re: Angled Polish Connectors and DWDM
On 9/30/2012 6:14 AM, Aaron Glenn wrote: sent mostly towards the cladding and not the core and therefore. Indeed. I have always held the idea that APC connectors induced greater chromatic and/or polarization mode dispersion -- yet can't find any resources that claim so, nor does that fit in with my working mental model of how light propagates. Just something I picked up during the hellish days of trying to deploy 10GbE before it was cool; now I'd like to know if it is grounded in any science (-: Thanks aaron Just tossing this in here. I don't claim to know either way. On the current project I'm working on all of the panels are LC-APC. This seems to have not been a problem for our DWDM vendor, who we have been working very closely with, and I assume know about our use of APC. So far our PMD testing has come back clear.
IETF's PIM Working Group conducting deployment survey
Hi, After a snafu, the PIM working group has restarted its survey into PIM sparse mode deployments. Please see the email at http://www.ietf.org/mail-archive/web/pim/current/msg02479.html for more information. responses will be anonymised. Many thanks to all operators who are able to respond. Adrian
Re: Angled Polish Connectors and DWDM
On Sun, 30 Sep 2012, ML wrote: So far our PMD testing has come back clear. How have you done the PMD testing? For verifying PMD and CD through an actual wavelength (not per-fiber, but through all the ADMs etc), I haven't really been able to find a good solution. Suggestions welcome. -- Mikael Abrahamssonemail: swm...@swm.pp.se
Re: Angled Polish Connectors and DWDM
On 9/30/2012 12:46 PM, Mikael Abrahamsson wrote: On Sun, 30 Sep 2012, ML wrote: So far our PMD testing has come back clear. How have you done the PMD testing? For verifying PMD and CD through an actual wavelength (not per-fiber, but through all the ADMs etc), I haven't really been able to find a good solution. Suggestions welcome. All tests done per span on dark fiber. CDs via a Nettest FD440: 1520nm to 1640nm PMD via a PerkinElmer* device: Just at 1550nm. -ML Couldn't find a model number in the test results. Just a reference to PerkinElmer.
Re: /. Terabit Ethernet is Dead, for Now
On 9/29/12, Masataka Ohta mo...@necom830.hpcl.titech.ac.jp wrote: Jared Mauch wrote: ... The problem is that physical layer of 100GE (with 10*10G) and 10*10GE are identical (if same plug and cable are used both for 100GE and 10*10GE). Interesting.Well, I would say if there are no technical improvements that will significantly improve performance over the best possible carrier Ethernet bonding implementation and no cost savings at the physical layer over picking the higher data rate physical layer standard, _after_ considering the increased hardware costs due to newly manufactured components for a standard that is just newer. E.g. If no fewer transceivers and fewer strands of fiber required, or shorter wavelength required, so it doesn't enable you to achieve greater throughput over the same amount of light spectrum on your cabling, and therefore lower cost at sufficient density, then: in that case, there will probably be fairly little point in having the higher rate standard exist in the first place, as long as the bonding mechanisms available are good for the previous standard. Just keep bonding together more and more data links at basic units of 10GE, until the required throughput capacity has been achieved. It's not as if a newer 1 Tbit standard, will make the bits you send get read at the other end faster than the speed of light. Newer standard does not necessarily mean more reliable, technically better, or more efficient, so it is prudent to consider what is actually achieved that would benefit networks considered to be potential candidates for implementation of the new standard, before actually making it a standard... -- -JH
Re: guys != gender neutral
Ugly would usually be considered pejorative. Owen On Sep 29, 2012, at 20:59 , Keith Medcalf kmedc...@dessus.com wrote: Ugly bags of mostly water? --- () ascii ribbon campaign against html e-mail /\ www.asciiribbon.org -Original Message- From: Otis L. Surratt, Jr. [mailto:o...@ocosa.com] Sent: Friday, 28 September, 2012 05:33 To: nanog@nanog.org Subject: RE: guys != gender neutral Maybe the OP for really nasty attacks in hindsight wishes NANOGers was used instead to address the list. :) Having all walks of life essentially all around, it really makes one careful to truly think before speaking. Sometimes we miss this with everything we have going on, but no one is perfect. The bottomline is, no one can really sastifisfy any indivdual and their preference of how they would liked to be addressed. If one is to be offended or looks for offense they will capitalize on it period. I try much as possible to avoid those situations. When we refer to our clients in a mass communication we either utilize our tools to auto fix their name to the letter or we address them as OCOSA Family or All or Clients. We are a very family-oriented business and are down to Earth. We'd like to believe our clients are apart of our family and some may take offense but you might or never would know unless an opportunity presented itself. Personally, I practice using the person's name, I am in communication with...not buddy, bud, pal, man, guys, gal y'all and etc. When addressing mixed gender groups, I simply speak or address as all. Thus, no mistakes. When addressing both genders you have to be extremely careful. Ultimately, It depends on the audience and treating all with respect seems to work for me. For example: You could address a group a men and call them boys. Well, that might offend some, especially if they are older than you. For example: You could address a group of young adults and call them kids. Well, that might offend some. As Owen mentioned saying human seems okay and true but then again, because it's not the norm it raises some question. (Internal thinking process, Oh I'm a HUMAN, well I that is true then your temperature gets back to normal) :) In general, this is life and I simply have fun and enjoy it because it's too short. Otis
Re: /. Terabit Ethernet is Dead, for Now
On 9/30/12 12:05 PM, Jimmy Hess wrote: On 9/29/12, Masataka Ohta mo...@necom830.hpcl.titech.ac.jp wrote: Jared Mauch wrote: ... The problem is that physical layer of 100GE (with 10*10G) and 10*10GE are identical (if same plug and cable are used both for 100GE and 10*10GE). Interesting.Well, I would say if there are no technical improvements that will significantly improve performance over the best possible carrier Ethernet bonding implementation and no cost savings at the physical layer over picking the higher data rate physical layer standard, _after_ considering the increased hardware costs due to newly manufactured components for a standard that is just newer. There is a real-estate problem. 10 sfp+ connectors takes a lot more space than one qsfp+. mtp/mpo connectors and the associated trunk ribbon cables are a lot more compact than the equivalent 10Gbe footprint terminated as LC. When you add cwdm as 40Gb/s lr4 does the fiber count drops by a lot. E.g. If no fewer transceivers and fewer strands of fiber required, or shorter wavelength required, so it doesn't enable you to achieve greater throughput over the same amount of light spectrum on your cabling, and therefore lower cost at sufficient density, then: in that case, there will probably be fairly little point in having the higher rate standard exist in the first place, as long as the bonding mechanisms available are good for the previous standard. Just keep bonding together more and more data links at basic units of 10GE, until the required throughput capacity has been achieved. It's not as if a newer 1 Tbit standard, will make the bits you send get read at the other end faster than the speed of light. Newer standard does not necessarily mean more reliable, technically better, or more efficient, so it is prudent to consider what is actually achieved that would benefit networks considered to be potential candidates for implementation of the new standard, before actually making it a standard... -- -JH
Re: /. Terabit Ethernet is Dead, for Now
joel jaeggli wrote: The problem is that physical layer of 100GE (with 10*10G) and 10*10GE are identical (if same plug and cable are used both for 100GE and 10*10GE). Interesting.Well, I would say if there are no technical improvements that will significantly improve performance over the best possible carrier Ethernet bonding implementation and no cost savings at the physical layer over picking the higher data rate physical layer standard, _after_ considering the increased hardware costs due to newly manufactured components for a standard that is just newer. There is a real-estate problem. 10 sfp+ connectors takes a lot more space than one qsfp+. mtp/mpo connectors and the associated trunk ribbon cables are a lot more compact than the equivalent 10Gbe footprint terminated as LC. That's why I wrote: (if same plug and cable are used both for 100GE and 10*10GE). As is mentioned in 40G thread, 24 Port 40GE interface module of Extreme BD X8 can be used as 96 port 10GE. When you add cwdm as 40Gb/s lr4 does the fiber count drops by a lot. That's also possible with 4*10GE and 4*10GE is a lot more flexible to enable 3*10GE failure mode trivially and allows for very large skew. Masataka Ohta
Re: /. Terabit Ethernet is Dead, for Now
On 30/09/12 20:05, Jimmy Hess wrote: On 9/29/12, Masataka Ohtamo...@necom830.hpcl.titech.ac.jp wrote: Jared Mauch wrote: ... The problem is that physical layer of 100GE (with 10*10G) and 10*10GE are identical (if same plug and cable are used both for 100GE and 10*10GE). Interesting.Well, I would say if there are no technical improvements that will significantly improve performance over the best possible carrier Ethernet bonding implementation and no cost savings at the physical layer over picking the higher data rate physical layer standard,_after_considering the increased hardware costs due to newly manufactured components for a standard that is just newer. E.g. If no fewer transceivers and fewer strands of fiber required, or shorter wavelength required, so it doesn't enable you to achieve greater throughput over the same amount of light spectrum on your cabling, and therefore lower cost at sufficient density, then: in that case, there will probably be fairly little point in having the higher rate standard exist in the first place, as long as the bonding mechanisms available are good for the previous standard. When you consider 100GBASE-LR4 (with its 4x25G form factor) there is some efficiency to be gained. ADVA others now support the running of each channel on their DWDM muxes at ~28G, to suit carrying 100GBASE-LR4 over four of your existing waves. CFPs with 4xSFP+ tunable optics in the front are out there for this reason. Once you get your head (and wallet) around that, there becomes a case for running each of your waves at 2.5x the rate they're employed at now. The remaining question is then to decide if that's cheaper than running more fibre. Still a hard one to justify though, I agree. I've recently seen a presentation from EPF** (by Juniper) that was *very* interesting in the 100G race, from a technical perspective. Well worth hunting that one down if you can, as it details a lot about optic composition in future standards, optic densities/backplanes, etc. Tom ** I couldn't justify going, but the nerd porn is hard to turn down. :)
Re: Angled Polish Connectors and DWDM
We have been using APC connectors on our DWDM deployments now for about 5 years and have had no issues with it at all. Additionally, last year we engaged several DWDM system providers and one of the questions we asked them was, did they know of any issues with APC connectors especially with regard to dual polarization systems. All vendors came back with having no issues with APC connectors. On 1 October 2012 06:15, ML m...@kenweb.org wrote: On 9/30/2012 12:46 PM, Mikael Abrahamsson wrote: On Sun, 30 Sep 2012, ML wrote: So far our PMD testing has come back clear. How have you done the PMD testing? For verifying PMD and CD through an actual wavelength (not per-fiber, but through all the ADMs etc), I haven't really been able to find a good solution. Suggestions welcome. All tests done per span on dark fiber. CDs via a Nettest FD440: 1520nm to 1640nm PMD via a PerkinElmer* device: Just at 1550nm. -ML Couldn't find a model number in the test results. Just a reference to PerkinElmer. -- Daniel Griggs Network Operations e: dan...@fx.net.nz d: +64 4 4989567
