April 2008 - Test - lists.nanog.org

Any tool or theorical method on detecting number of computer behind a NAT box?
by Joe Shen 07 Apr '08

07 Apr '08

hi, Sharing internet access bandwidth between multiple computers is common today. Usually, bandwidth sharer bought a little router with NAT/PAT function. After connecting that box to a ADSL/LAN access link, multiple computer could share a single access link. I heard some company provide prdouct for detecting number of computers behind NAT/PAT box. Is there any paper or document on how such product work? where could I fint them ? Joe ______________________________________________________________________ Search, browse and book your hotels and flights through Yahoo! Travel. http://sg.travel.yahoo.com

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Re: rack power question, and a prediction about "direct heat removal" (DHR)
by Kevin Blackham 06 Apr '08

06 Apr '08

Forgive if this is duplicate. Too many posts in the various forks of this thread to dig through them all. http://www.troxaitcs.com/aitcs/products/co2_mcc/index.jsp http://www.modbs.co.uk/news/fullstory.php/aid/1735/The_next_generation_of_c… "CO2 has the additional benefit that should a leak occur, it is electrically benign. Imagine the consequences of a leak of water or refrigerant. While a leak of CO2 could be a health-and-safety hazard, the risk is minimised by CO2 detection as part of the system." > On Thu, Apr 3, 2008 at 11:58 PM, Patrick Giagnocavo <patrick(a)zill.net> wrote: > > > > > First, I would like to thank everyone who responded to my initial query. > > > > It seems that power and how to remove the resulting heat, is certainly on a lot of people's minds. > > > > Clearly the days of "including" power are past in all but sales and marketing materials. > > > > There is a cost to each component and markup is applied (if internally and not broken out to the customer) on each rack, each power circuit, etc. with covering the overhead of UPS, diesel generator, chillers, etc. being a big priority. > > > > After some thought, I believe, to coin a term, that "DHR" or direct heat removal, in some fashion will be the "new" thing for the datacenter. > > > > Somewhat counter-intuitively, the focus will be to remove the heat that comes out the back of the rack rather than worrying so much about the temperature of the air going in the front as long as it falls in a generally acceptable range of say, 68-75F. > > > > My guess is that someone will come up with an inexpensive, reliable way to put a heat collector, which will basically look like a car radiator the size of a rear rack door, directly behind the hot air coming from the systems in the rack. > > > > Hot air flows past the cooling fins and is quickly cooled back to 68F; the heated refrigerant is immediately piped away, out of the room and to the chiller, so that the evil BTUs do not spread out and contaminate other areas of the room. > > > > It might involve a phase change material, or might involve a more traditional refrigerant. > > > > My money would be on R744, also known as CO2, as it is not polluting and can serve double duty as fire suppression (provided you have enough on hand to flood the area/room). > > > > Detectors for leaks are very inexpensive and the technology for the closed-loop of the refrigerant cycle is already here. > > > > It is not caustic the way any of the salts-based variants would be, is not explosive, and is heavier than regular air, meaning it will sink below the area that most people breathe at should there be a small leak. > > > > With the heat being removed within a few inches of where it is generated, less CRAC units will be needed to keep the rest of the air cooled; and possibly, no separate unit would be needed if enough heat can be removed to drop the temperature below 68F. > > > > For fire suppression, an alarm would sound and only when it can in some fashion be "proven" that no humans are inside the area, CO2 is flooded into the area and the fire goes out. Some form of ducting which mixes the CO2 with regular air and exhausts it is needed after the fire is out. Firemen go in with oxygen if they need to enter before this is done. (obviously there would be an entire tested procedure for how this is done, probably including a small oxygen mask with ~4 minutes of O2 placed beside each fire extinguisher and within easy reach). > > > > (For racks with less than say 4KW of power use, network and power is fed from overhead with a few feet of slack in the cables, as well as a portion of the DHR piping being flexible tubing. This allows them to be placed more closely together than normal, almost front to back to front to back, with enough slack to pulled the wheeled racks "out" from the stack so it can be worked on (sort of like pulling a book out of a bookshelf). They use far less space and are sold a little cheaper by the colo facility.) > > > > Surely there is a limit as to how much air can be moved around, even with the use of best practices, there are hot spots. > > > > Simple physics dictates that this is a less energy intensive cooling method as a) moving a lot of air around requires a lot of energy b) air is a lousy way to transfer heat away from where you want it to be compared to other materials. > > > > Cordially > > > > Patrick Giagnocavo > > patrick(a)zill.net > > > >

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Re: Comcast problems?
by Ted Fischer 06 Apr '08

06 Apr '08

I didn't save any of my Wireshark traces, but this is what I observed (I'm behind Charter at home but visiting my brother in NJ - Comcast territory). All attempts to check my e-mail (neither Charter nor Comcast) showed the syns going out but no syn acks coming back. Then, after a few minutes (pop server time outs I guess) I started seeing fins coming back from the pop server that matched my connection requests. Saw that occur with various http connection attempts as well. Of course, the only reason I can send this reply out is that they appear to be back up. Any chance of getting a non-nonsensical RFO from someone? Ted At 02:16 PM 4/5/2008, you wrote: >On Sat, Apr 5, 2008 at 1:44 PM, Steven M. Bellovin ><smb(a)cs.columbia.edu> wrote: > > > The fact that I get different behavior for different protocols makes me > > suspect they're having trouble with equipment designed to control p2p > > traffic. Their help phone line simply speaks of an outage. Service > > has come back occasionally, but not for long. The problem has been > > going on since about 6am. > > > > Does anyone have any data? > >wasn't it sandvine last time? did you try calling them as well? All >joking aside, one hopes that these sorts of things show that the 'p2p >control' soutions are far from perfect and far from 'well baked' and >likely still very ill-advised. > >-Chris

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Re: "Does TCP Need an Overhaul?" (internetevolution, via slashdot)
by Hank Nussbacher 06 Apr '08

06 Apr '08

At 03:54 PM 05-04-08 -0500, Jorge Amodio wrote: >outstanding compilation Hank, thanks !!! >>I suggest reading the excellent page: >>"High-Speed TCP Variants": >>http://kb.pert.geant2.net/PERTKB/TcpHighSpeedVariants > >Rgds >-Jorge It is the result of the Geant2 SA3 working group. There is much more there than just TCP variants. Regards, Hank

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Akamai/Speedera outages this weekend?
by david raistrick 05 Apr '08

05 Apr '08

Anyone know anything about the Speedera (now Akamai) outages this weekend? https://cachecontrol.speedera.com/cgi-bin/cpurge.pl has been off and on unreachable since last night, which is causing fits for some parts of our application... of course, I have been able to find zero contact information for our account with speedera/akamai internally...anyone know anything? ..david --- david raistrick http://www.netmeister.org/news/learn2quote.html drais(a)icantclick.org http://www.expita.com/nomime.html

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Nanog 43/CBX -- Hotel codes etc
by David Diaz 05 Apr '08

05 Apr '08

Since several members pointed out I should post this information as people are buying their plane tickets here it is: If you plan on staying over in NY for a few extra nights to attend CBX or just enjoy the city you will need to use the codes below. I would recommend calling the hotel since you will need your nanog code as well as the CBX code below for your longer duration stay. Also, if you are PLANNING ANY EVENTS during the nanog and wish that information passed on to other attendees please feel free to forward me your event. I can also help make sure it does not conflict with any other events. I do know there are events planned for the weekend prior to nanog and there are events afterwards during the CBX. TIPS: New York is a wonderful city, however, as with any large city travel safely -Do not use your iPod white ear pieces. Especially on the subway at night -Travel in groups or with a local -Know where you are going ahead of time so you do not need to keep the map open -Using your laptop on the train at night and storing it in a big laptop bag that says LAPTOP or FORUM on it is a no-no -DO NOT go to the wonderful local Apple Store and walk around the city with that white APPLE bag full of iPhones -Stay on the main streets not the allays especially off-Broadway -Car services from the hotel are flat rates and very cost effective. It's a very safe city for the last decade but travel smartly and enjoy. Anyone wishing to be invited or included in any events around the city or sponsored activities please email me at davediaz AT telx.com or davediaz AT gmail.com > HOTEL CODES: Rates for June 4th & 5th at the Brooklyn Bridge Marriott use CODE # TXBTXBA Click here to book now http://cwp.marriott.com/nycbk/cbx/ Cocktail Event at Battery Park Gardens Wednesday June 4th 7 - 11pm - R.S.V.P to jsauer(a)telx.com - All NANOG Attendees are invited Telx Customer Business Exchange "CBX" Thursday June 5th 9am - 3pm Visit http://cbx.telx.com to register *It is FREE to attend - All NANOG Attendees are invited > David Diaz telx +++++++++++++++++++++++++++++++ FACTA NON VERBA

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Time Warner NOC contacts.
by Kirk Winkelman 05 Apr '08

05 Apr '08

If there is anyone from Time Warner NOC on this list, please contact me at kirk.winkelman(a)gmail.com. We are seeing issues with DNS caching inside the RR network. Thanks, Kirk Winkelman Positive Networks

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Comcast problems?
by Steven M. Bellovin 05 Apr '08

05 Apr '08

Anyone know what's going on with Comcast? From my house, I can reach a few sites with TCP (fortunately, that includes my office, so I could set up a web and email proxy). If I use traceroute, I can get more or less anywhere. If I use a UDP-based traceroute, I can get responses back from the first 8 hops. If I use a TCP-based traceroute, I get nowhere. The fact that I get different behavior for different protocols makes me suspect they're having trouble with equipment designed to control p2p traffic. Their help phone line simply speaks of an outage. Service has come back occasionally, but not for long. The problem has been going on since about 6am. Does anyone have any data? --Steve Bellovin, http://www.cs.columbia.edu/~smb

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RE: cooling door
by Frank Coluccio 05 Apr '08

05 Apr '08

Michael Dillon is spot on when he states the following (quotation below), although he could have gone another step in suggesting how the distance insensitivity of fiber could be further leveraged: >The high speed fibre in Metro Area Networks will tie it all together >with the result that for many applications, it won't matter where >the servers are. In fact, those same servers, and a host of other storage and network elements, can be returned to the LAN rooms and closets of most commercial buildings from whence they originally came prior to the large-scale data center consolidations of the current millennium, once organizations decide to free themselves of the 100-meter constraint imposed by UTP-based LAN hardware and replace those LANs with collapsed fiber backbone designs that attach to remote switches (which could be either in-building or remote), instead of the minimum two switches on every floor that has become customary today. We often discuss the empowerment afforded by optical technology, but we've barely scratched the surface of its ability to effect meaningful architectural changes. The earlier prospects of creating consolidated data centers were once near-universally considered timely and efficient, and they still are in many respects. However, now that the problems associated with a/c and power have entered into the calculus, some data center design strategies are beginning to look more like anachronisms that have been caught in a whip-lash of rapidly shifting conditions, and in a league with the constraints that are imposed by the now-seemingly-obligatory 100-meter UTP design. Frank A. Coluccio DTI Consulting Inc. 212-587-8150 Office 347-526-6788 Mobile On Sat Mar 29 13:57 , sent: > >> Can someone please, pretty please with sugar on top, explain >> the point behind high power density? > >It allows you to market your operation as a "data center". If >you spread it out to reduce power density, then the logical >conclusion is to use multiple physical locations. At that point >you are no longer centralized. > >In any case, a lot of people are now questioning the traditional >data center model from various angles. The time is ripe for a >paradigm change. My theory is that the new paradigm will be centrally >managed, because there is only so much expertise to go around. But >the racks will be physically distributed, in virtually every office >building, because some things need to be close to local users. The >high speed fibre in Metro Area Networks will tie it all together >with the result that for many applications, it won't matter where >the servers are. Note that the Google MapReduce, Amazon EC2, Haddoop >trend will make it much easier to place an application without >worrying about the exact locations of the physical servers. > >Back in the old days, small ISPs set up PoPs by finding a closet >in the back room of a local store to set up modem banks. In the 21st >century folks will be looking for corporate data centers with room >for a rack or two of multicore CPUs running XEN, and Opensolaris >SANs running ZFS/raidz providing iSCSI targets to the XEN VMs. > >--Michael Dillon

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rack power question
by Patrick Giagnocavo 05 Apr '08

05 Apr '08

Hopefully this classifies as on-topic... I am discussing with some investors the possible setup of new datacenter space. Obviously we want to be able to fill a rack, and in order to do so, we need to provide enough power to each rack. Right now we are in spreadsheet mode evaluating different scenarios. Are there cases where more than 6000W per rack would be needed? (We are not worried about cooling due to the special circumstances of the space.) Would someone pay extra for > 7KW in a rack? What would be the maximum you could ever see yourself needing in order to power all 42U ? Cordially Patrick Giagnocavo patrick(a)zill.net

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