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Subnetting to limit broadcast traffic


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#16 Daedroth

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Posted 01 April 2013 - 19:26

Here is a screen shot of the previous statement on "Tagging" Macs to a VLan... I think this is the screen that I am looking for below? I am close to being out of addresses... yes! I am also getting a lot of broadcast floods/errors and from what I am reading by (subnetting or VLAN) I can cut down on the broadcast traffic. So kind of both.

Here is what I was looking at.. if I understand the screen right. These are 2 Netgear GS748TPS switches linked with HDMI.

You don't want to be adding MAC addresses, that will get messy. Also you might want to rethink how your switches are connected, as I somehow doubt its via HDMI!


#17 +BudMan

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Posted 01 April 2013 - 19:50

connected via HDMI?? I find that unlikely as well ;)

do you mean fiber?

See on your screen there where it says voice vlan, that should be how you can setup your phones to be on their own vlan while pc connected to them on some other vlan.

But I really would suggest you use different connections for your phones and your other devices - it gives you way more control and options going forward then running connection over the same wire.

#18 OP Unrealism2k

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Posted 01 April 2013 - 20:08

the switches are chained in the back with a HDMI cable to talk to each other. Seriously! I am looking at it, and if I pull it I lose contact with the other switch. lol. It's weird I know!

I went to the VoiceLAN area, and we do have it enabled (as far as I know) to basically tag the MAC's of Polycom phones. And we have it on VLan 2. However, all ports are listed as "Untagged" so I don't even know if the VLan is in affect exactly.

#19 sc302

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Posted 01 April 2013 - 20:14

the screen that you took an image of, you don't want to be there.

perhaps vlan.

as far as the hdmi...yep according to netgears website they are using the hdmi for stacking....strange indeed
http://www.netgear.c...748tps.aspx#two

2 HDMI ports on the rear of the unit – used for stacking only



#20 +BudMan

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Posted 01 April 2013 - 20:17

Stack cable ok, well WTF ;) Guess its nice they are not using a proprietary cable.

http://countries.net...=Specifications

2 HDMI ports on the rear of the unit – used for stacking only

#21 StrikedOut

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Posted 01 April 2013 - 20:19

How are your phones powered? Mains or PoE? If mains invest in enough PoE switches for your needs and separate the traffic. Not sure what the quality of your calls are like but call quality can be an issue if you have a busy LAN.

#22 sc302

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Posted 01 April 2013 - 20:19

Would also suggest you read up on the manual
http://www.downloads..._UM_15Jun09.pdf

#23 OP Unrealism2k

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Posted 01 April 2013 - 20:19

I thought the HDMI stacking was odd as well. Well here is where I am at... I can't run any cables anytime soon to seperate the phones (Which would be nice). I am almost out of address's so I need to change the subnet accordingly, and what do we think we can do about the broadcast traffic breakdown? I assume that is also why our internet (20/20 speed) is hit and miss lately as well because of all the traffic on the same subnet? Because it seems fine late at night after 5 when there is nothing in use.

#24 sc302

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Posted 01 April 2013 - 20:21

How are your phones powered? Mains or PoE? If mains invest in enough PoE switches for your needs and separate the traffic. Not sure what the quality of your calls are like but call quality can be an issue if you have a busy LAN.

The switch, if you looked up the model based on the screen shot he provided on page one, is poe.

I thought the HDMI stacking was odd as well. Well here is where I am at... I can't run any cables anytime soon to seperate the phones (Which would be nice). I am almost out of address's so I need to change the subnet accordingly, and what do we think we can do about the broadcast traffic breakdown? I assume that is also why our internet (20/20 speed) is hit and miss lately as well because of all the traffic on the same subnet? Because it seems fine late at night after 5 when there is nothing in use.

your internet traffic has little to nothing to do with the broadcast, and everything to do with what your computers are requesting. You would have to do some qos to prioritize traffic to the voice side vs the data side.

#25 OP Unrealism2k

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Posted 01 April 2013 - 20:24

How are your phones powered? Mains or PoE? If mains invest in enough PoE switches for your needs and separate the traffic. Not sure what the quality of your calls are like but call quality can be an issue if you have a busy LAN.


They are running POE, quality seems good. We had some intermittent issues here and there. Sometimes still we get random call drops, etc. But it also could be 8x8's service. It will go days just fine and some days it is a mess.





Would also suggest you read up on the manual
http://www.downloads..._UM_15Jun09.pdf


I've been trying to make heads and tails of it. Just trying to figure out the best option.

your internet traffic has little to nothing to do with the broadcast, and everything to do with what your computers are requesting. You would have to do some qos to prioritize traffic to the voice side vs the data side.


As far as I can tell we are using QOS for the Voice. Thats where I am unsure if it is actually "Working" or not. We have it setup to tag the Macs of Polycom phones and send it to VLan 2 with the same subnet 255.255.255.0. However there is a section in the netgear config where you can "Tag" the ports. and they all have a U for "Untagged" so I am not sure if it is even monitoring the Mac's of those phones.

#26 StrikedOut

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Posted 01 April 2013 - 20:30

The switch, if you looked up the model based on the screen shot he provided on page one, is poe.

My bad. When I read it, I read it as the TS not TPS. We did a similar exercise a few years ago. Separated the 2 and it made managing the network a lot easier.

#27 sc302

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Posted 01 April 2013 - 20:43

I would strongly suggest running other cables for your voice, it really makes things easier. Logistically, management wise, and speed wise.

Take your phone and play with the vlan tagging and untagging with that.

#28 +BudMan

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Posted 01 April 2013 - 21:01

Why do you think broadcast traffic is what is causing your issues? There are ways to turn off some of the nonsense broadcasting that might be going on if that is the case.

I would run a sniff on your pc during the day, busy part of the day.. Let it run for say 30 minutes. Then look at it and see what portion of the traffic is broadcast.. I would assume that switch has the ability to do IGMP snooping - which can lower the amount of multicast traffic to your devices as well.

I doubt your using SSDP, so that could be turned off.. A sampling of the type of broadcast traffic your seeing, and I am sure you could reduce the amount of it quite a bit!! With some changes in your OS settings, disable services.

Off the top I would think by default all your PCs are able to be browser - when there is NO point to that, so they are sending out that traffic I bet - so simple disable of computer browser service on all your PCs other than your servers you would want to be master browser would reduce broadcast.

Grab wireshark (free) log some traffic for period of time - and then lets look at the type and amount of broadcast traffic your seeing and we can see what we can do to reduce it.

example:

I grabbed only a few seconds of traffic on this work network (which I do NOT MANAGE BTW - my box just sits on this network) There is a bunch of clean up I would do, and things I would do WAY DIFFERENT!!

But as you can see - only a few seconds and quite a bit of nonsense that could be removed. Got users running dropbox with lan sync enabled - maybe they are syncing with other workers? Doubt it - notice the browser looking for web URLS - thats because they browsers are not correctly setup not too, and they query dns and it dies not respond because only the proxy here can do outside dns queries. Notice the machines announcing they can be browser, pointless for them to do that. See the multicast SSDP traffic - again pointless on a work network! We sure an the hell are not using any UPnP stuff...

Dhcp is about the only thing on there that should be seen ;) And you could reduce the amount of that depending on your lease time, etc.

examplebroadcast.jpg

And that was only a couple of seconds and pointed out stuff that could be done to reduce broadcast/multicast traffic. So lets see yours.. Run it for longer or just start with a few seconds and we can point out stuff I am sure.

Post up the statistics breakdown, etc. You looking to reduce nonsense traffic - are you using IPv6? Bet you all your boxes have all that stuff enabled sending out noise for something you have no use of, etc.

I find it unlikely that broadcast/multicast is killing your network - but sure its possible you got some storms going on?? We can clean up the stuff that does not need to be there for sure, prob won't make much impact on your performance overall - but its good house keeping regardless of any performance impact.

and just if your curious, no none of that is from my box
IP Address. . . . . . . . . . . . : 10.56.41.184
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.56.41.1

#29 OP Unrealism2k

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Posted 02 April 2013 - 15:10

Ok, here are some screenshots I took today, I am not sure how to really read this, so any suggestions... =/

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Screen Shot 2013-04-02 at 11.06.56 AM.png
Screen Shot 2013-04-02 at 11.07.03 AM.png
Screen Shot 2013-04-02 at 11.07.10 AM.png
Screen Shot 2013-04-02 at 11.07.17 AM.png

#30 +BudMan

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Posted 02 April 2013 - 15:22

Well I don't see much noise there other than a few people running lan sync on their dropbox - do they sync to each other? If not I would have them turn off lan sync option. See couple of hosts doing browser announcements, you can clean that up via disable of computer browser service on all but the servers or pcs that are going to be your master browser for MS network browsing.

Looks like that is about 30 seconds or so from time stamp of your first pic to your last, if that is all your seeing its not much broadcast or multicast.

So I am not sure why you think broadcast traffic is causing your network issues?

edit: looks like your 1.176 in those sniffs - looks like your running dropbox lan sync as well ;)



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