August 2009 - Test - lists.nanog.org

Network topology
by Colin Alston 15 Nov '13

15 Nov '13

Hi all I'm considering trying to come up with some means to automatically detect a networks topology and draw pretty pictures. This is somewhat boring though if a network isn't well arranged with VLANs and q-tag trunk routers and so on (It will just look like a big cloud of junk connected off an assumed switch). Is there any kind of cunning trick to detect standard layer2 switches along a path without stuff like STP?

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Inventory and workflow management systems
by vijay gill 26 May '13

26 May '13

What software solution do people use for inventory management for things like riser/conduit drawdown, fiber inventory, physical topology store, CLR/DLR, x-connect, contracts, port inventory, etc. Any experiences in integrating workflow into those packages for work orders, modeling, drawdown levels, etc. /vijay

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Wireless bridge
by Peter Boone 05 Apr '10

05 Apr '10

Hi NANOG, I'm looking for some equipment recommendations for a wireless bridge between two locations approximately 500-800 meters apart. The current setup for this company has been extremely unstable and slow. I don't have a lot of experience in this area so I was hoping someone could give me a few pointers. Currently, both locations are using Linksys WRT54GL's flashed with DD-WRT firmware (Yes, 802.11g. All extra bells and whistles are disabled in the firmware. They were set up for WDS so other wireless clients could connect to the same access point, with varying degrees of success. Not very important). They are connected to SmartAnt 2300-2500 MHz 14 dBi directional antenna mounted on the roof (extended pretty high for perfect line of sight). I'm not sure when they got these antenna exactly but I'm told it was when WiFi was very new. The network is very small so both locations share the same subnet (192.168.1.0/24). They have gone through numerous Linksys access points over the years. The wireless settings are tweaked as best as possible, and we have found the connection to be most stable when the TX is limited to 6-9 Mbps. We have explored other options as well. An internet connection at each location + VPN is out due to very slow upstream speeds (the buildings are in an industrial area, ADSL is the only option.) The max they offer on regular business accounts is 800 kbps up. T1 lines are even slower and even more expensive. They won't offer us any other solutions such as fibre. We have considered running fibre/coax but there is too much construction activity and other property in the way. I'm looking into RouterBOARD right now, considering a RB433AH and R52H wireless card, but I'm not sure this will actually solve the problem. It's difficult to determine if the issue is with the antennas or access points (for example, after a good thunderstorm, the wireless link will be down for at least 12 hours, but will fix itself eventually. Resetting either access point will keep the link down for at least 30 minutes. Using an airgun on the access points tends to make them more reliable, even if they are clean and dust free. From the admin interface, each access point will report seeing a very good and strong signal from the other, yet they refuse to communicate until they feel like it a few hours later.) Any suggestions welcome. I'm sure you can tell cost is a bit of a factor here but it will be easy for me to justify a higher price if I'm confident it will be effective. While I'm at it, I've been reading along on the list for over a year now; thanks everyone for sharing your real world experiences :) Peter

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Voice Operators' Group: voiceops.org
by Hiers, David 12 Feb '10

12 Feb '10

Hi Everyone, I'm pleased to announce that the Voice Operators' Group has found an excellent home. Our web site, www.voiceops.org has a good home (thanks Scott!), while Jared, Daniel, and all the great folks over at nether.net are hosting our list server. If VoiceOps can do for voice anything close to what NANOG has done for IP, we'll all owe much to the people that are making this happen. email: voiceops-subscribe(a)voiceops.org web: https://puck.nether.net/mailman/listinfo/voiceops Thanks, David Hiers CCIE (R/S, V), CISSP ADP Dealer Services 2525 SW 1st Ave. Suite 300W Portland, OR 97201 o: 503-205-4467 f: 503-402-3277 This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system.

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Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?
by Adam Hebert 02 Oct '09

02 Oct '09

Multiple providers are seeing this right now. I assume someone is advertising an extremely long AS_PATH again? anyone else seeing this? Adam

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OSPF vs IS-IS vs PrivateAS eBGP
by Clue Store 12 Sep '09

12 Sep '09

Hi All, I know this has been discussed probably many times on this list, but I was looking for some specifics about what others are doing in the following situations. I would like to run an IGP (currently OSPF) to our customers that are multi-homed in a non-mpls environment. They are multi-homed with small prefixes that are swipped from my ARIN allocations. OSPF has been flaky at best under certain conditions and I am thinking of making the move to IS-IS. I have also seen others going to private AS and running eBGP. This seems a bit much, but if it works, i'd make the move to it as I like bgp the most (all of the BGP knobs give me the warm and fuzzies :). I'd also like to see what folks are using in a MPLS network?? OSPFv3 or IS-IS or right to MP-BGP and redist static from the CE to PE??? On and off list are welcome. I'll make a summary after I gather the info. Thanks, Clue

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Re: FCCs RFC for the Definition of Broadband
by Deepak Jain 05 Sep '09

05 Sep '09

Key characteristics of broadband : always on capability (reasonably, DSL ok, dial up no). I would argue 7mb is broadband even if its over carrier pigeon. (meets always on criteria). I think the threshold for cut off is somewhere between 256kbit/s and 1.5mbit/s. If you don't think 1.5mbit is broadband, you need to consider tiers... Most of the worlds population will not see *that* speed in 20yrs. Deepak ----- Original Message ----- From: Jeffrey Lyon <jeffrey.lyon(a)blacklotus.net> To: nanog(a)nanog.org <nanog(a)nanog.org> Sent: Wed Aug 26 19:09:47 2009 Subject: Re: FCCs RFC for the Definition of Broadband I would argue that "broadband" is the upper X percentile of bandwidth options available to residential users. For instance, something like Verizon FiOS would be broadband while a 7 Mbps cable wouldn't. Jeff On Wed, Aug 26, 2009 at 6:39 PM, Richard Bennett<richard(a)bennett.com> wrote: > They have a saying in politics to the effect that "the perfect is the enemy > of the good." This is a pretty good illustration. We have the opportunity to > improve connectivity in rural America through the wise expenditure of > taxpayer funding, and it's best not to squander it by insisting on top-shelf > fiber or nothing at all. Let's push the fiber a little deeper, and bridge > the last 20,000 feet with something that won't be too expensive to replace > in 3-5 years. The budget ($7B) just isn't there to give every barn some nice > GigE fiber, even though it would make the cows happy. > > Richard Bennett > > -----Original Message----- > From: Joe Abley [mailto:jabley@hopcount.ca] > Sent: Wednesday, August 26, 2009 1:42 PM > To: Fred Baker > Cc: nanog(a)nanog.org > Subject: Re: FCCs RFC for the Definition of Broadband > > > On 26-Aug-2009, at 13:38, Fred Baker wrote: > >> If it's about stimulus money, I'm in favor of saying that broadband >> implies fiber to the home. > > I'm sure I remember hearing from someone that the timelines for disbursement > of stimulus money were tight enough that many people expected much of the > money to remain unspent. > > Does narrowing the scope of the funding to mandate fibre have the effect of > funding more and better infrastructure, or will it simply result in less > money being made available? Does it matter? > > > > > -- Jeffrey Lyon, Leadership Team jeffrey.lyon(a)blacklotus.net | http://www.blacklotus.net Black Lotus Communications of The IRC Company, Inc. Platinum sponsor of HostingCon 2010. Come to Austin, TX on July 19 - 21 to find out how to "protect your booty."

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Request for a pointer - Linux modifying DSCP on replies?
by Darren Bolding 04 Sep '09

04 Sep '09

I believe this is operational content, but may well be better asked somewhere else. I would love to have a pointer to another list/website. I am looking to do some policy routing based on DSCP marking, and I have this all working inside the networking equipment. I DSCP mark some packets at ingress and I policy-route others based on ACL's matching those DSCP markings. This should allow me to solve some problems in a rather elegant manner, if I do say so myself. And this works fine for some things- I have verified that Ping's to a host work as expected- the Ping shows up at the destination host DSCP marked, and the ICMP reply leaves with the same DSCP marking. However, when I do this with apache and mysql connections (TCP 80/3306), the incoming packets are marked, but the replies are not. My research into the subject doesn't seem to suggest there is a standard for whether replies to a TCP connection are required to have the same DSCP marking, but it seems to make a lot of sense that they would. I've disabled iptables on the server host to no avail. I've looked around for an apache or Linux kernel setting and found nothing. At this point I'm looking for pointers- to a way to solve this issue, or to a better place to ask. I've started investigating writing iptables rules to match incoming connections that have DSCP marking and explicitly mark response traffic, but that seems, I don't know... wrong. Linux kernel we are using is 2.6.9-67.ELsmp. Any help or pointers would be appreciated! --D -- -- Darren Bolding -- -- darren(a)bolding.org --

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Re: Link capacity upgrade threshold
by Bill Woodcock 03 Sep '09

03 Sep '09

>>> If your 95th percentile utilization is at 80% capacity... >> s/80/60/ > s/60/40/ I would suggest that the reason each of you have a different number is because there's a different best number for each case. Looking for any single number to fit all cases, rather than understanding the underlying process, is unlikely to yield good results. First, different people have different requirements. Some people need lowest possible cost, some people need lowest cost per volume of bits delivered, some people need lowest cost per burst capacity, some need low latency, some need low jitter, some want good customer service, some want flexible payment terms, and undoubtedly there are a thousand other possible qualities. Second, this is a binary digital network. It's never 80% full, it's never 60% full, and it's never 40% full. It's always exactly 100% full or exactly 0% full. If SNMP tells you that you've moved 800 megabits in a second on a one-gigabit pipe, then, modulo any bad implementations of SNMP, your pipe was 100% full for eight-tenths of that second. SNMP does not "hide" anything. Applying any percentile function to your data, on the other hand, does hide data. Specifically, it discards all of your data except a single point, irreversibly. So if you want to know anything about your network, you won't be looking at percentiles. Having your circuit be 100% full is a good thing, presuming you're paying for it and the traffic has some value to you. Having it be 100% full as much of the time as possible is a good thing, because that gives you a high ratio of value to cost. Dropping packets, on the other hand, is likely to be a bad thing, both because each packet putatively had value, and because many dropped packets are likely to be resent, and a resent packet is one you've paid for twice, and that's precluded the sending of another new, paid-for packet in that timeframe. The cost of not dropping packets is not having buffers overflow, and the cost of not having buffers overflow is either having deep buffers, which means high latency, or having customers with a predictable flow of traffic. Which brings me to item three. In my experience, the single biggest contributor to buffer overflow is having in-feeding (or downstream customer) circuits which are of burst capacity too close to that of the out-feeding (or upstream transit) circuits. Let's say that your outbound circuit is a gigabit, you have two inbound circuits that are a gigabit and run at 100% utilization 10% of the time each, and you have a megabit of buffer memory allocated to the outbound circuit. 1% of the time, both of the inbound circuits will be at 100% utilization simultaneously. When that's happening, you'll have data flowing in at the rate of two gigabits per second, which will fill the buffer in one twentieth of a second, if it persists. And, just like Rosencrantz and Guildenstern flipping coins, such a run will inevitably persist longer than you'd desire, frequently enough. On the other hand, if you have twenty inbound circuits of 100 megabits each, which are transmitting at 100% of capacity 10% of the time each, you're looking at exactly the same amount of data, however it arrives _much more predictably_, since the 2-gigabit inflow would only occur 0.0000000000000000001% of the time, rather than 1% of the time. And it would also be proportionally unlikely to persist for the longer periods of time necessary to overflow the buffer. Thus Kevin's ESnet customers, who are much more likely to be 10gb or 40gb downstream circuits feeding into his 40gb upstream circuits, are much more likely to overflow buffers, than a consumer Internet provider who's feeding 1mb circuits into a gigabit circuit, even if the aggregation ratio of the latter is hundreds of times higher. So, in summary: Your dropped packet counters are the ones to be looking at as a measure of goodput, more than your utilization counters. And keep the size of your aggregation pipes as much bigger than the size of the pipes you aggregate into them as you can afford to. As always, my apologies to those of you for whom this is unnecessarily remedial, for using NANOG bandwidth and a portion of your Sunday morning. -Bill

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Link capacity upgrade threshold
by devang patel 01 Sep '09

01 Sep '09

Hi All, I just wanted to know what is Link capacity upgrade threshold in terms of % of link utilization? Just to get an idea... thanks, Devang Patel

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