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Wireless Networks Thread, Meru in Technical; Hi, I have a couple of questions about the Meru wireless that I hope people may be able to help ...
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    Meru

    Hi,

    I have a couple of questions about the Meru wireless that I hope people may be able to help me with.

    When the AP forms a tunnel to carry the VLANs (one per SSID), where does the tunnel terminate? I assume it terminates in the Controller?
    Is it possible for AP to form a tunnel with the Controller and once the client is authenticated and associated with the SSID then fall back to tagging on the edge (so traffic doesn't need to go through the Controller)?

    What I am concerned about is a bottleneck on the cable (1Gbit) from the Controller to the core layer 3 switch.

    E.g. What if you have 80x AP332i (802.11ac) APs passing all traffic via the Controller? That's potentially up to 80Gbit of traffic (in theory) over a 1Gbit cable.

    Also, I understand that Meru APs operate on one 'virtual' channel. What does this actually mean? Do the APs and clients literally operate on one channel and one channel alone, or do they connect on one 'virtual' channel and then get shifted to another real channel?

    Thanks,

    Bruce.
    Last edited by Bruce123; 7th August 2014 at 05:05 PM.

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    My controller has 4 gb ports

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    Quote Originally Posted by andydis View Post
    My controller has 4 gb ports
    Ours does too. And I am assuming we can bundle these into an Etherchannel group, but it would still lead to a potential bottleneck (when you have say > 20 ac access points). Ideally, there should be at least one 10Gbit connection (e.g. SFP slot).

    Thanks,

    Bruce.

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    In general controllers/aggregating traffic back to a central location doesn't cause to much overhead currently (depending on the network design). But with the adoption of 802.11ac in your case this is going to become and issue. A lot of wireless vendors now (Like Aerohive/Airtight and now Aruba) are creating controller-less products to tackle this problem. This basically means that everything is handled at the AP from a data/control perspective allowing the wireless to not have to traverse the network. It also makes things like QoS/policy enforcement/firewalling etc easier. It also allows you to control what hits the network and what doesnt.

    In the case of Meru this shouldnt be a massive issue, as Meru only uses a single channel and doesn't have the ability to hit the same speeds as multi channel solutions.

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    If you don't want all traffic to go through the controller make dataplane mode into bridge and tag ap vlan, make sure every ap broadcasting that ssid is tagged also on the swtich.

    Btw even 8 Gbit of traffic does not sound like real life.

    Personally I turn off virtual cell since it usually does not work good with high density (depending how you define it)

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    Quote Originally Posted by njc235 View Post
    Meru has to be installed correctly but I would like to challenge a couple of points here;

    Data traffic does not go through the controller once a client is authenticated. In fact loss of a controller would only prevent roaming or attach/reattach. A static user would continue to be connected to the network and be able to send/receive data.
    This is basically what I wanted to know (i.e. that not all wireless traffic goes through the Controller).

    I am however, having trouble understanding how this works.

    Once the client is authenticated, the only way I can see this working is if AP ends the tunnel and does the frame tagging on the edge (and is connected to a 802.1Q trunk port on the edge switch)

    E.g.

    Client A connects to Wireless1, frames get tagged VLAN 10 by the AP
    Client B connects to Wireless2, frames get tagged VLAN 20 by the AP
    Client C connects to Wireless3, frames get tagged VLAN 30 by the AP

    Then your Layer 3 switch does the Inter-VLAN routing in the usual way.

    Is this how it works?

    Many Thanks,

    Bruce.
    Last edited by Bruce123; 8th August 2014 at 11:09 AM.

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    Apologies, there was a mistake in my previous post. I am seeking clarification this afternoon.

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    Quote Originally Posted by mke1 View Post
    If you don't want all traffic to go through the controller make dataplane mode into bridge and tag ap vlan, make sure every ap broadcasting that ssid is tagged also on the swtich.
    Does this basically meaning disabling AP<->Controller tunnelling and allow the APs to perform the tagging?

    In this scenario, the edge switch, and any intermediary switches, and the layer 3 switch would need to be aware of each VLAN (and the layer 3 switch would obviously need an IP range/IP address for each VLAN). That's not actually a problem as all APs are at the local site.


    Btw even 8 Gbit of traffic does not sound like real life.
    I know what you're saying, 4Gbit sounds like plenty, but this is supposed to be future proof (i.e. last 8 years). Who knows what we may need it for in 2-3 years? Our Internet connection has recently been upgraded to 1Gbit (in 5 years it would probably be 10Gbit).

    Just on contention ratios: with 4x1Gbit ports available on the Controller we have 4Gbit uplink, which is 5% of the potential throughput from all 80 APs.

    Compare this to a typical 48-port 100Mbit edge switch with a 1Gbit (or perhaps 2x1Gbit) uplink. This would be 20% (or 40%) of the potential throughput.

    Thanks,

    Bruce.
    Last edited by Bruce123; 8th August 2014 at 07:36 PM.

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    MCA networks offer much more scalability than SCA networks for a fraction of the cost. Per a high-end Meru VAR, building ubiquitous single-channel layers across a campus adds about a 50% cost penalty (at minimum) to have 3 layers for 2.4GHz and only 2 layers for 5GHz. That's pretty steep considering that MCA networks can scale far beyond that level for 50% less cost. Heavy saturation comes from 2 things: high client density and heavy utilization by those clients. A single channel can only withstand a given amount of utilization until it saturates, wherein lies Meru's scalability problem. By use many times as much free bandwidth, MCA systems can far out-scale SCA. When interference happens in a particular area, MCA systems can have ONLY the AP covering that particular area change its channel to recover that available bandwidth, whereas SCA systems cannot. Meru's system doesn't support high client density at all. Their system is limited to (64 - #SSID per radio), which means if there are 4 SSIDs on a radio, they are limited to 60 client connections on that radio. That would mean 120 clients per AP.

    Worry less about the ethernet ports and more about the air contention!

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    Their system is limited to (64 - #SSID per radio), which means if there are 4 SSIDs on a radio, they are limited to 60 client connections on that radio.

    Not sure where did you get that and what ap and controller you are talking about but that is not true. I got way over 70 devices with one radio only and working fine with ap 320

    I agree that multi channel works better for high density but it may be a problem to set ip up for somebody

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    Quote Originally Posted by mke1 View Post
    Not sure where did you get that and what ap and controller you are talking about but that is not true. I got way over 70 devices with one radio only and working fine with ap 320

    I agree that multi channel works better for high density but it may be a problem to set ip up for somebody
    Did you have 4 SSIDs?

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    Quote Originally Posted by wifispray View Post
    Did you have 4 SSIDs?
    Yes, even more, some not enabled

    With your counting it should not work anyway

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    Quote Originally Posted by mke1 View Post
    Yes, even more, some not enabled

    With your counting it should not work anyway
    Ill take your word it worked great with 70 clients on an AP320..... That would be a lot of overhead with Virtual Cell enabled on 1 radio.

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    I did not say I use virtual cell, actually I always turn it off

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    We have Meru, we have the older 3000 series controller (soon to be unsupported) which has just 2xGb ports and these are not teamed, but run in redundancy mode so we only have a single GB port for connectivity to the network.

    We have 600 iPads, 300 Laptops and other personal devices hanging off the wireless system and the bandwidth rarely gets above 200MB/s when you monitor it on an average day, both on the controllers own monitoring and on the port monitoring on the switch. It performs flawlessly, really quick fast and reliable for us. What you have to remember is it's extremely rare for all the devices to be used at the same time.

    I don't know how large your site is, but I had the same worries as you when we started out, but they really were not worth worrying about as they were non existant problems. Unless your site is extremely large, the 3200 series controller with 4 GB ports will serve you just fine I would think. I also find the key to having a smooth Meru system is access point density - we have one in every room and several in the large spaces.

    Incidentally the access point to controller communication on our meru system is done in layer 2, the controller just has to be on the same VLAN as the AP's and they automatically latch onto it, all the VLAN and layer 3 access is done from the controller - this makes it super easy if you want to introduce new VLAN's to the wireless system as you only have to tag them on the ports the controller is using and not every single access point. I also have 5 SSID's running on the system across the site and I've never had an issue with client connectivity. Meru is a very capable wireless system and it gets top marks from me, even thou it is expensive it's well worth the money.

    Mike.



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