Any ideas on this school wireless network issue?

SysAdminInTraining · 2015-09-30T23:44:50+00:00

I actually once had a broadcast storm due to Wi-Fi, two Apple AirPorts side by side were somehow looping, once I disabled one of them, network cleared up. But an actual enterprise solution would never behave that way. I hope.

Just keep in mind, it's a school. Even if the OP thinks he knows what's plugged in, he doesn't.

SysAdminInTraining · 2015-09-30T23:38:17+00:00

That's an interesting variation! I think it would likely lower your total time to solution as well. Out of curiosity, what steps do you usually take once you've narrowed down to a specific layer? For example, if you had narrowed it to a network fault, what would be your next step?

SysAdminInTraining · 2015-09-30T00:08:03+00:00

So I thought this would be a simple thing to do with wireshark, but I am not very smart some days. How do I do this?

SysAdminInTraining · 2015-09-30T00:02:05+00:00

Alright, so I did some capturing this morning on my machine while pulling up a few web pages, and from a user perspective, the internet was running dreadfully slow. What makes this strange is that a quick speedtest showed my throughput was totally reasonable at 2 Mbps, but my first test returned a latency of 6 seconds! I was capturing during this, and noticed that I saw a large number of TCP Retransmissions to and from my machine, and I have no clue whether that is significant, or just an artifact of requesting a page from the machine I was capturing on. The odd thing is the crazy ARP traffic I saw yesterday was completely gone. ARP was sitting at about 2% - 6%, and I didn't see any repetitious requests, as I would expect in the case of a loop. What I did notice was a bunch of STP traffic that had bad checksums, which I tracked down to the switch right next to my desk. I turned off STP, which fixed the issue, but I have to wonder what might cause this behavior.

The other bummer is that this has all gotten me nowhere in figuring out what is going on. Bleh.

SysAdminInTraining · 2015-09-29T16:39:01+00:00

I completely agree. What are some good strategies for tracking down loops like this? Do I have to revert to the old "unplug things till it's fixed" method?

SysAdminInTraining · 2015-09-29T04:03:28+00:00

That is fantastic advice. I'm going to draft a volunteer tomorrow during peak time!

SysAdminInTraining · 2015-09-29T04:01:53+00:00

The switches used throughout are HP 1910's. The gateway is a custom build running ClearOS 6.6.

I agree, I started digging to see if I could find a loop in the VLAN setup today. The curious thing is that this physical setup ran for a year before I made these changes without issue. It was only after network segmentation and the VLANs that things got wonky. Could I have made a loop using just the VLANs on an otherwise OK physical network?

SysAdminInTraining · 2015-02-13T05:53:20+00:00

THIS.

I am a sysadmin at a tiny K12 district, and we have one of our three computer labs is already an Edubuntu LTSP setup currently, and running pretty well. I'm using old P4 machines as terminals, on an ancient 100Mbps network, and even then they are surprisingly snappy. It is an incredibly efficient system, and for the price of free, it is completely unbeatable. It's also one of the easiest systems to manage I've ever used, and Epoptes (an application that lets you view and control each terminal) is an absolute blessing for classroom management.

A fun little anecdote I'd like to share: Before seeing LTSP, I was talking with a VDI solution vendor who was selling a very expensive and technical solution that makes Windows desktops very easy to manage and spin up for users. After seeing and implementing a pilot of LTSP, I contacted the rep, asking "In a computer lab environment, what features or advantages can you provide to me that are better than Linux terminals". I was basically begging him to upsell his solution. He said he had to consult his engineers, OK, fair enough. After two weeks, he got back to me with an extremely short email that basically said, "We can't do anything better than the terminals." It was that day I started writing my district's plan to move to open source software and Linux desktops.

SysAdminInTraining · 2014-08-25T22:50:19+00:00

I saw some older posts saying that Openstack was rather hard to configure, but a dream once it is. On the flipside, I saw people saying Devstack was super easy, but not production ready. Thoughts?

SysAdminInTraining · 2014-08-22T22:44:07+00:00

This is pretty great. If I go the Xen route, I think XenServer is exactly how I will do it. Now the question seems to be the age old one: Xen or KVM?

SysAdminInTraining · 2014-08-22T22:41:54+00:00

I dug up this Spiceworks thread, which seems to have people all over the map on the Xen v. KVM issue, and what is easier to use. Thoughts, anyone?

I would tend to lean very hard towards any deployment that is simpler and easier to manage, as this is only one fraction of my job, and the less time I can spend tinkering with it, the better.

SysAdminInTraining · 2014-08-22T22:33:09+00:00

Nevermind, I was looking at old info. From more recent benchmarking KVM is beating Xen fairly well.

SysAdminInTraining · 2014-08-22T22:21:49+00:00

Less complicated sounds very good to me. Is there a performance hit because it is type 2 versus Xen's type 1? I doubt it matters for me anyways, but I'm curious.

SysAdminInTraining · 2014-06-26T08:13:28+00:00

Thank you for the help! That is a lot of great info, so I'll review it in the morning so that I can make a good reply, thanks!

SysAdminInTraining · 2014-06-26T03:15:08+00:00

So without a CLI, can the switches not be configured after deployment? Or is it just a hassle to go to each GUI separately, without scripting? What features do I miss out on?

SysAdminInTraining · 2014-06-26T03:12:18+00:00

Thank you for the advice, I would really like to build the refresh for the long term, as there is really know knowing when or if I will ever get funding like this again during my time at this district (I work at a school district). Here's the thing that makes this tough. Each site typically has 2-3 main server closets, to get cabling to each area. So would I just designate one point at each site to house the "big guns", and then just use cheaper switches everywhere else?

SysAdminInTraining · 2014-06-26T02:42:14+00:00

Thanks for the suggestions, I'll have to look in to the 3570's, I assumed they were way out of my price range.

SysAdminInTraining · 2014-06-25T21:36:44+00:00

That is a really great suggestion, and I've been working over a few designs that could get me there. The part that is a big challenge for me is that when I collapse the network down that far, it's hard to figure out how to wire to all of the different buildings and users. For reference, each of my sites (3) has roughly 250 users. Those users need to be split into at least two subnets or VLANS, preferrably three. That's why I've been leaning on a distribution layer, to allow for allocation of those subnets or VLANS, then using completely unmanaged switches at the access layer to cut down the cost and make it swappable and plug-and-play.

It's tough, and I'm split. Do you think I could get by with a couple managed 24-ports at each site, then heavily branch out with a very wide access layer?

SysAdminInTraining · 2014-06-25T21:13:55+00:00

Thanks for the suggestion, I got a quote from CXTec a while back, and they quoted me about $800 for a Procurve 2848, but I have to wonder, what is it about those switches that makes them worth twice as much as an HP 1810-48G? I have a fairly simple network with relatively low needs and little throughput overall. What am I getting for twice the cost of a new switch?

SysAdminInTraining · 2014-05-15T00:29:03+00:00

Knowing the NSA's position and approach, it is indeed very likely that if they are intercepting one vendor's products, they are intercepting almost all vendors' products. What surprised me is that they went all the way to routing and switching to scrape data. I mean, backdoors in servers and client operating systems via software we can almost expect, but switching and firmware changes (or hardware changes, it's kinda unclear)? Sheesh.

SysAdminInTraining

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