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Why choose 120 volts?
by Seth Mattinen 28 May '09

28 May '09

I have a pure curiosity question for the NANOG crowd here. If you run your facility/datacenter/cage/rack on 120 volts, why? I've been running my facility at 208 for years because I can get away with lower amperage circuits. I'm curious about the reasons for using high-amp 120 volt circuits to drive racks of equipment instead of low-amp 208 or 240 volt circuits. ~Seth

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RIPE NCC does a series of interviews about IPv6 deployment
by Alex Band 28 May '09

28 May '09

As part of our IPv6 training project, that consists of face to face training and on-line learning modules and testimonials, I am proud to announce the first in a series of interviews. Andy Davidson of NetSumo ISP Consultancy discusses the IPv6 deployment they have done for their customers and themselves: http://www.youtube.com/watch?v=QCcigLJJbvU So far, we have interviewed 22 people from the community about their experiences and are very busy editing all the video material. In the coming months, you will be able to enjoy the rest of the interviews here: http://www.youtube.com/user/RIPENCC These interviews will also be published on our e-learning page and on our IPv6 Act Now website: http://ripe.net/training/e-learning/ http://www.ipv6actnow.org/ Cheers, Alex Band RIPE NCC

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Re: Packet loss statistics
by Chris Robb 28 May '09

28 May '09

The Internet2 network publishes 10-second data for all interfaces on both its backbone network and the individual racklans in each of its cities: Backbone: http://dc-snmp.grnoc.iu.edu/i2net/ Racklans: http://dc-snmp.grnoc.iu.edu/i2net-hp/ Default graphs don't show errors. You need to create a custom graph and click the appropriate checkbox. If you want to view a large number of interfaces with their errors on a single page, you can create a Custom View that includes errors for any number of selected interfaces. -Chris On May 28, 2009, at 12:03 PM, Ric Messier wrote: > > Is anyone aware of useful resources for packet loss over large LANs > and WANs? Google turned up a nice statistics page for Qwest's > network but not much else that seems useful to me. > > Our testing teams are trying to simulate expected network conditions > and rather than go overboard, having something close to real-world > parameters would be nice. > > Thanks! > Ric > Chris Robb, Internet2 Manager of Operations O: 812.855.8604 C: 812.345.3188 **************** ESCC/Internet2 Joint Techs July 19-23, 2009 - Indianapolis, Indiana http://jointtechs.es.net/indiana2009/

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Re: Why choose 120 volts?
by joel jaeggli 28 May '09

28 May '09

If the pdu contains a surge suppressor and was designed for 120v, plugging in to 220 will cause the MOV that protects against transient over-voltage to emit smoke. The breaker or fuse is a current limiting device. Joel Pete Templin <petelists(a)templin.org> wrote: >Dave Larter wrote: >> Seems like if the c14 was connected to a 240v PDU the 5-15 would >> deliver 240v to the equipment, arc/pop tripping the breaker on the >> PDU as soon as it is connected killing power to everything on that >> PDU. Or am I missing something? > >If you plug a PDU into a service that's higher voltage than expected, >why would the PDU circuit breaker trip? That breaker is measuring >current, AFAICT, though in the end it might be measuring power. >Regardless, it isn't measuring voltage, because that isn't constant >(it's AC, after all) and is likely to drop under a short circuit, not >skyrocket like the current will. > >pt >

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Re: MX Record Theories
by gb10hkzo-nanog＠yahoo.co.uk 28 May '09

28 May '09

On Wed, 27 May 2009 09:48:39 -0400, <gb10hkzo-nanog(a)yahoo.co.uk> wrote: > Actually, I was thinking to myself yesterday that the email world is going to be awfully > fun when IPv6 sets in and we're all running mail servers with nice long AAAA records such as > fc00:836b:4917::a180:4179. > You do realize DNS queries aren't passing around addresses in ASCII? 3 additional bytes per address isn't going to break the bank. I think you might have missed the point of my post. It was a tounge in cheek reply to the poster who suggested bad things happen if the DNS message size exceeds 512 bytes. He was commenting about AOL's MX records which currently weigh in at 507 bytes. Therefore if we were to hypothesise that the world ends at 512 bytes, then companies doing things the way AOL does, but using IPv6 addresses rather than IPv4 addresses for their MX records could run into "problems". Hope that clarifies :)

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Re: Why choose 120 volts?
by Robert Bonomi 28 May '09

28 May '09

> Subject: Re: Why choose 120 volts? > Date: Thu, 28 May 2009 01:11:41 +0200 > > On 27 mei 2009, at 18:03, Peter Beckman wrote: > > > I haven't seen a PC power supply which is incapable of both 120v/ > > 60hz and > > 240v/50hz in a very long time. > > After this nice voltage discussion, what about hertz? Would it be more > efficient for us Europeans to run our stuff at 60 Hz rather than 50? I > hear that a 50 Hz grid loses 15% more due to inefficiencies than a 60 > Hz grid. Not sure if that also applies over short distances, though. _Transformer_ losses are greater at lower frequencies. And the cores have to be bigger. That is the primary reason military avionics, and other onboard gear use 400Hz AC. Note: The U.S. as recently as immediate post WW-II had some areas of 25-Hz power. Transformer based equipment that was designed to be "just adequate" for 60Hz mains was known to 'let the smoke out' when plugged in in one of those 25Hz areas.

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None
by gb10hkzo-nanog＠yahoo.co.uk 27 May '09

27 May '09

> fc00:836b:4917::a180:4179 And yes, before anyone points out, I just realised I posted an abbreviated example. :)

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Re: MX Record Theories
by gb10hkzo-nanog＠yahoo.co.uk 27 May '09

27 May '09

Mark, > A EDNS referral from the root servers to the COM servers > already exceeded 512 bytes. The world hasn't fallen over. Actually, I was thinking to myself yesterday that the email world is going to be awfully fun when IPv6 sets in and we're all running mail servers with nice long AAAA records such as fc00:836b:4917::a180:4179. :)

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Re: Out of warranty APC PDU repair
by Oliver Hookins 27 May '09

27 May '09

On Wed May 27, 2009 at 03:17:24 -0400, Barton F Bruce wrote: > *This message was transferred with a trial version of CommuniGate(r) Pro* > > ----- Original Message ----- From: "Oliver Hookins" > <oliver.hookins(a)anchor.com.au> > To: <nanog(a)nanog.org> > Sent: Wednesday, May 27, 2009 12:47 AM > Subject: Out of warranty APC PDU repair > >> Hi all, hopefully this isn't too off topic (since it's datacentre >> related). >> >> We have an APC AP7952 rack PDU which has stopped working. I believe the >> management module is faulty, and it is about 5 years old. APC don't >> service >> these outside of warranty at all so I'm trying to find a 3rd-party >> repairer. >> So far APC doesn't seem to understand this concept. >> >> Can anyone suggest a company that would work on these units in Sydney, >> Australia or nearby? > > One company here in the USA that might talk you through figuring out what > is wrong and then can supply repair pars is Gruber Power Services in > Phoenix. > > Google for GRUBER POWER as they have several domains , though > www.gruber.com probably will work, too. > > They are one division of Gruber out there that also custom builds fiber > jumpers and makes custom rack shelves and makes 1U 24 and 32 port RJ45 to > variously wired 25 and 32 pair champ connectors. and a myriad of other > things. They buy refurbish and sell LARGE UPSes and related gear of many > brands. Also have good prices on UPS batteries for folks here in the USA > in spite of UnitedParcelService shipping prices... If you are ordering > pallet loads, truck becomes very attractive. Small quantities, use their > EBAY store as it is very automated and they give you a slightly better > price that way on small orders. > > Good folks! We did a site inspection of their facilities years ago right > after a Nanog meeting that was in Scottsdale. By then they were already > making several custom things for us and we were delighted to see where it > all came from. > > They can easily do custom punched and bent, drilled, tapped, etc steel or > aluminum "things" (typically RACK hardware) that can be left raw metal or > powder coated. Best price is NOT at some 10/50/110 like step but is > related to how many they can make of that item out of each standard sheet > of incoming metal. For example, they custom made us dense 96 port OC-48 > BNC panels in 19" and shorter in 23" sizes. D shaped holes and we let > idle NOC fingers load bulk bought 75 ohm insulated BNC feed-throughs when > and as needed. VASTLY less expensive than commercial offerings. Also got > a lot of 1U 16 hole blanks as we just string 8 pack of 735 cable to a > customer's racktop if they need T3s. That will take two such cables. > Unless they have a lot of RAS boxes that need many T3s, most anyone else > will prefer OC-x if they are getting much more capacity than that. > > Anyway, I hope they can help with your problem and it is INTERESTING to > hear how long or how short APC chooses to support users... Being as we are in Sydney, Australia and Gruber is in Phoenix, Arizona, USA, I don't think it'll be the most convenient arrangement. I just received a reply from APC saying even the warranty replacements don't get repaired. I guess there's a landfill somewhere full of faulty PDUs... -- Regards, Oliver Hookins Anchor Systems

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Out of warranty APC PDU repair
by Oliver Hookins 27 May '09

27 May '09

Hi all, hopefully this isn't too off topic (since it's datacentre related). We have an APC AP7952 rack PDU which has stopped working. I believe the management module is faulty, and it is about 5 years old. APC don't service these outside of warranty at all so I'm trying to find a 3rd-party repairer. So far APC doesn't seem to understand this concept. Can anyone suggest a company that would work on these units in Sydney, Australia or nearby? -- Regards, Oliver Hookins Anchor Systems

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