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Wired Networks Thread, Desperate for reasons NOT to buy HP Smart switches rather than fully managed in Technical; Well I have to disagree with you there. I noticed a real difference in the places where I did have ...
  1. #31

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    Well I have to disagree with you there. I noticed a real difference in the places where I did have 1Gb to the desktop. I cannot believe anyone working in a school thinks that there are only a view people trying to run video over their network. We run a streaming server and are moving old DVD'd and VHS tapes onto this format. Therefore the need to run video is becoming the norm

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    Hi snoerre

    You obviously understand this more than me. What is the real effect of only 256 entries in the ARP table? I imagine we will not have quite this many connecting to the switches in that block but it could be possible as soon as other students get near it and their wireless phones are assigned an IP address ( and therefore their Mac Address is retained). I'm not sure if the ARO table is populate by only authenticated devices of not. This 6th form block is located such that every student and teacher in the school walks past. I noticed that the very fact that a mobile device comes into range then there is a DHCP assigned address even if they are denied access. I can see this in my Ruckus WLAN controller and this caused the VLAN addresses to run out! This means having to reduce the lease time to a very short one to free up addresses.

    If the RP table gets filled what happens then?

  3. #33

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    The ARP table size only matters on the devices doing the routing, generally in schools that is the core switch and perhaps the wireless controller.

    The MAC table size on the other hand may matter. If your APs dump the client traffic directly into vlans on the edge switches, then the edge switches need to maintain 1 entry per device across the network. If your wireless APs tunnel back to a controller attached to the core, then there is no requirement for the edge switches to maintain any sort of track of the wireless clients, and a MAC Table size of 8192 is not a problem.

    On lease lengths. (keep with me, this probably seems like a strange approach to making layer 3 decisions): Generally with wifi you have a maximum of 75 active clients per wireless collision domain, and a maximum of 255 per layer 3 broadcast domain, so depending on your projected density and the number of concurrent devices you may need to increase the number of channels and subnets available to support them.... and thus the lease length is less important than you may think. Corollary to that is if your churn rate per day is low, and you don't have a large number of concurrent devices (i.e substantially less in a given day than the there are leases available), then a short (1 Day) lease time is good.

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    Dantech (12th May 2013)

  5. #34


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    Quote Originally Posted by Dantech View Post
    Well I have to disagree with you there. I noticed a real difference in the places where I did have 1Gb to the desktop. I cannot believe anyone working in a school thinks that there are only a view people trying to run video over their network. We run a streaming server and are moving old DVD'd and VHS tapes onto this format. Therefore the need to run video is becoming the norm
    yeah. I stream video over an ADSL line. There are plenty of reasons why you might need gigabit on the desktop, but streaming video isn't one.

  6. #35

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    Thanks for your advice. I appreciate the explanation.

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    Got to be honest though, with media editing, large photo editing, app-v downloading programs, saving work.....what in a school genuinely requires 1Gb to and end user? Serious question by the way, educate me on this as maybe there's something I'm missing? as I simply cannot see an application for it based on the files and work that students and teachers do and the file sizes they generally work with. Even when they're editing videos or streaming videos off the network. Have you even tested multiple PCs streaming videos at once? Have you definitely determined that it is the network speed and not the storage that is causing any slow down, if there even is any?

    EDIT: That's not meant to sound grumpy, i understand we all have different applications, so i genuinely want to know if there's a good reason to apply 1Gb to the desktop!
    Last edited by mrbios; 12th May 2013 at 08:06 PM.

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    Thanks psydii

    I think my AP's should dump the clients onto the Wireless VLAN but we never quite finished setting this up last summer and they are still in the default VLAN. This is something I need time to sort in the next long holiday. I have limited my maximum number of IP connections by AP (which I assume is the wireless collision domain) to 50 on the advice of Ruckus consultants. They should take up to 100 but to have one fail and lose 100 connections would be worse than losing 50. Ruckus spreads the load between adjacent AP's automatically. I have only ever seen 36 devices on one AP anyway.

  9. #38
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    Quote Originally Posted by mrbios View Post
    Got to be honest though, with media editing, large photo editing, app-v downloading programs, saving work.....what in a school genuinely requires 1Gb to and end user? Serious question by the way, educate me on this as maybe there's something I'm missing? as I simply cannot see an application for it based on the files and work that students and teachers do and the file sizes they generally work with. Even when they're editing videos or streaming videos off the network. Have you even tested multiple PCs streaming videos at once? Have you definitely determined that it is the network speed and not the storage that is causing any slow down, if there even is any?

    EDIT: That's not meant to sound grumpy, i understand we all have different applications, so i genuinely want to know if there's a good reason to apply 1Gb to the desktop!
    I'm going to agree with you mrbios, but not for the same reasons. I've got classes that work with photo/video editing too and to have a source file 3GB in size is a regular occurrence. They only get so much class time so I could definitely see the advantage to a 1Gb link. That being said though, I would never give clients 1Gb links if that is what the backbone and servers are running. If everything else was 10Gb, then sure, no problem! It's always been drilled into my head to not give access clients backbone speed, and to me this gets more important as the size of the network increases.

  10. Thanks to Duke5A from:

    mrbios (13th May 2013)

  11. #39
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    Quote Originally Posted by Duke5A View Post
    I'm going to agree with you mrbios, but not for the same reasons. I've got classes that work with photo/video editing too and to have a source file 3GB in size is a regular occurrence. They only get so much class time so I could definitely see the advantage to a 1Gb link. That being said though, I would never give clients 1Gb links if that is what the backbone and servers are running. If everything else was 10Gb, then sure, no problem! It's always been drilled into my head to not give access clients backbone speed, and to me this gets more important as the size of the network increases.
    I completely agree Duke, I much prefer to stage everything like you say, clients one step behind the infrastructure. Seems logical to me.

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    Quote Originally Posted by mrbios View Post
    I completely agree Duke, I much prefer to stage everything like you say, clients one step behind the infrastructure. Seems logical to me.
    Spot on.

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    Hi Everyone

    This just gets better - the guys buying the switches bought the HP V1905 PoE which is only a 10/100Mb Smart switch! This means that my four brand new Dual band Ruckus 1GHz AP's will not be able to pull the 850Mbps down that they do in the rest of the school - 100Mb will be the top, so performance will be pants, especially as this is the main start of BYOD deployment in a sixth form block. I also don't think these switches support RIP v 2 which is deployed out from my Core Switch. Not sure if this will cause a problem but will be interesting to see if routing will work properly. I'll know next week.

  14. #42

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    Lovely... Looks like your worse dreams may come true after all.
    Sit tight, put a smug grin on your face and keep reminding yourself It wasn't your choice or fault.

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