Jumbo Frames and Gigabit and QoS

kyuusei

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Sep 16, 2008
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Need some help with configuring my home network. Currently I have my desktop and a Gigabit NAS wired to a WRT610Nv1 and a HTPC + PS3 hooked up to an old WGT624 I'm using as a switch in the living room. Got a couple of other PCs connected via wireless. I'm trying to update the whole shebang to Gigabit and preferably Jumbo Frame support as well as adding in an expansion.

Currently going through the WRT610N gets me transfers speeds of ~200 Mbps while is comparable to what SmallNetBuilder.com got when they reviewed it, its far from Gigabit speeds. The WRT610N doesn't officially support Jumbo Frames (DD-WRT does but not entirely stable) either. Newegg has a buy 2 get 1 free deal on Netgear GS-105E Gigabit/Jumbo Frame switches which according to SmallNetBuilder.com, should be good for ~700 Mbps. So is it possible to get Jumbo Frame support by bypassing it with a switch? If it is, I'm thinking I can kill 2 birds with one stone, by bypassing the slow router with a fast switch and gain Jumbo Frames to boot.

networkra.jpg


A centralized switch would be great, but I can't run cables through the walls, I don't want to have cables strewn all over the floor. So one of the switches are gonna be right next to the Modem/Router, while the other two are gonna be in other parts of the house.

Oh and regarding QoS. My internet connection is pretty crappy (3MBps down/0.8MBps up on a good day) and my HTPC is often used to stream video off the internet while I'm trying to get a quick game of CS:S, CoD, whatever. When both are going at the same time, the HTPC streams just fine while I'm getting horrendous pings and lag spikes. Can QoS be used to limit my HTPC to say 1/3rd of my internet connection rather than just limiting it's LAN bandwidth? More specifically is possible with my network scheme from above using the QoS implementation in the Netgear GS-105E?
 
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mikey71497

Limp Gawd
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Sep 27, 2004
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If I am understanding your question correctly......Is the Netgear GS-105E capable of doing NAT and DHCP? Is this a layer 3 switch? If not, how do you plan on routing your internal IP space behind your WAN IP if you replace that router with a switch?
 

kyuusei

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Sep 16, 2008
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Well here's the product page for the GS-105E :http://www.newegg.com/Product/Product.aspx?Item=N82E16833122342&Tpk=gs-105e

As far as I can tell its a "semi-smart" switch. I'm not too well versed in networking, but I intend on supplementing rather than replacing the router with that switch. Router still handles DHCP and all that stuff. Just nothing plugs into it, everything plugs into the switches. Whether or not that would boost thoroughput by bypassing the "slow" router, or give me Jumbo Frames is the question I'm posing.
 

mikey71497

Limp Gawd
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Sep 27, 2004
Messages
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As long as that router remains as your "edge device" it will remain your bottleneck. The switches may pass the jumbo frames amongst one another, but once the frame ingresses your router (as this is the final edge device to get to the web) it will take those jumbo frames and either frag them, or drop them. Any frame or packet over the routers default MTU size, (not sure if you can change that setting or not) will be treated as best effort resulting in one of the two scenarios mentioned above. Your best bet is to get a router, that supports jumbo frames or that has a setting to change the MTU size on its LAN/WAN interfaces.

And keep in mind that one of your switches will need to connect to the router LAN port in order for the network to function properly. You can't have "nothing" plugged into the router. If that was the case, how would each node on your network request a IP addy from the router? Just food for thought.
 
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Got a couple of other PCs connected via wireless. I'm trying to update the whole shebang to Gigabit and preferably Jumbo Frame support as well as adding in an expansion.
Is there a specific reason why you want jumbo frames? Normally, the bigger the frame size, the harder QoS has to work to do its job properly. That's because small packets have to wait even longer for big packets to be processed. All else being equal, jumbo frames will make your problems worse.

So is it possible to get Jumbo Frame support by bypassing it with a switch? If it is, I'm thinking I can kill 2 birds with one stone, by bypassing the slow router with a fast switch and gain Jumbo Frames to boot.
Yes - this is an extremely good idea. Adding an extra switch to the network is nearly always going to be better than plugging something directly into a router.

Can QoS be used to limit my HTPC to say 1/3rd of my internet connection rather than just limiting it's LAN bandwidth?
It looks like your switch supports either port-based custom rate limits or 802.1p, but not both at the same time. So you could set a fixed limit for your HTPC's port, give its streaming application a lower priority, or give your game a higher priority on the network.
 

kyuusei

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Sep 16, 2008
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As long as that router remains as your "edge device" it will remain your bottleneck. The switches may pass the jumbo frames amongst one another, but once the frame ingresses your router (as this is the final edge device to get to the web) it will take those jumbo frames and either frag them, or drop them. Any frame or packet over the routers default MTU size, (not sure if you can change that setting or not) will be treated as best effort resulting in one of the two scenarios mentioned above.

It doesn't really matter at that point for me at that point, my internet connection is too slow to make use of Gigabit or Jumbo Frames. I'm looking for the extra speed mainly for computer -> computer streaming of files.

And keep in mind that one of your switches will need to connect to the router LAN port in order for the network to function properly. You can't have "nothing" plugged into the router. If that was the case, how would each node on your network request a IP addy from the router? Just food for thought.

Obviously that's a given. When I say nothing, I mean no PCs, NASes, etc will be plugged into the router. The router would be only linked to the modem and the switch. Every other device goes through a switch that supports Jumbo Frames and Gigabit.

Is there a specific reason why you want jumbo frames? Normally, the bigger the frame size, the harder QoS has to work to do its job properly. That's because small packets have to wait even longer for big packets to be processed. All else being equal, jumbo frames will make your problems worse.

Mainly the thought that it can help boost network speeds. I do a lot of HD streaming and large backups across the network and having Jumbo Frames wouldn't hurt even if it doesn't work very well in my application and I have to disable it.

It looks like your switch supports either port-based custom rate limits or 802.1p, but not both at the same time. So you could set a fixed limit for your HTPC's port, give its streaming application a lower priority, or give your game a higher priority on the network.

While that would give my game higher priority on the network, its all the same once it hits the router and needs to pull bandwidth off the internet not? My internet connection is the bottleneck in this scenario.
 
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delvryboy

2[H]4U
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Feb 21, 2008
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If you're looking for PC>PC, then the switches will make a big difference. The router nor your internet speed won't matter.
 

NetJunkie

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You guys worry WAY too much about jumbo frames on 1Gb switches. It's not worth the hassle.
 
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While that would give my game higher priority on the network, its all the same once it hits the router and needs to pull bandwidth off the internet not?
Setting a fixed rate limit on the switch like you said will work.
Your router in theory supports both 802.11p tags and MAC-address based QoS, but when I did a search I saw a lot of complaints about problems with the QoS settings not applying or not working or something. Have you tried them already? It should be quick to set up a MAC address priority and see whether it works.

Maybe it will work better with DD-WRT.
 

kyuusei

n00b
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Sep 16, 2008
Messages
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Setting a fixed rate limit on the switch like you said will work.
Your router in theory supports both 802.11p tags and MAC-address based QoS, but when I did a search I saw a lot of complaints about problems with the QoS settings not applying or not working or something. Have you tried them already? It should be quick to set up a MAC address priority and see whether it works.

Maybe it will work better with DD-WRT.

Yeah QoS on the router doesn't work very well or not at all. I haven't tried loading DD-WRT on it yet because it isn't rock stable yet.

Right now, I'm stuck choosing between Netgear's GS108E or GS108T. The E has simple egress and ingress rate limiting, but you're stuck using an app to manage it. The T only has simple egress rate limiting and if you wanna mess with ingress, you'll have to dick about with DiffServ which confuses me to hell and back.
 
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