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To gigabit, or not to gigabit? That is the question!


ILoveC4

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Dan - did you change the switch ports things were plugged into. Sounds like a physical media problem. If you changed the cable out already there may be a port speed mismatch. Check the ethernet settings on each device and on the switch. I've seen problems with auto negotiation of link speed - eg. the switch things a device is has negotiated to 1gb and the device things 100mb - also check your duplex settings.

All that is WAY over my head. I am not a network guy at all. It was streaming from my ReadyNAS NV+ to my EVA9150...both are gigabit I believe.

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In the admin interface for your eva you should be able to check the status of the network port on the eva. It will tell you wether it's connected via 10mb, 100mb, or 1000gb, and whether it can send and receive data at the same time: full duplex vs, half duplex. Check the currently used settings and write them down.

Go into the admin interface for the switch and check the current status of the port # that the EVA is plugged into. The settings should match what you found on the EVA.

Do the same thing for the ReadyNas. If the settings match port vs. device you're ok and we can look elsewhere. If they don't, post back here and I'll tell you what to do next.

A mismatch in speed or duplex can cause performance problems.

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In the admin interface for your eva you should be able to check the status of the network port on the eva. It will tell you wether it's connected via 10mb, 100mb, or 1000gb, and whether it can send and receive data at the same time: full duplex vs, half duplex. Check the currently used settings and write them down.

Go into the admin interface for the switch and check the current status of the port # that the EVA is plugged into. The settings should match what you found on the EVA.

Do the same thing for the ReadyNas. If the settings match port vs. device you're ok and we can look elsewhere. If they don't, post back here and I'll tell you what to do next.

A mismatch in speed or duplex can cause performance problems.

When I have a chance I will figure out how to log in to the admin interface and check it out. Once I get a chance to do that I will report back. Hopefully I can do that today or tomorrow.

Thanks.

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...

snip

...

Does it sound like enabling Jumbo Frames would fix this problem?

Thanks.

I cannot be emphatic enough, but NO. I am just an ordinary C4 user, but my job is in high-end corporate computing including data center networking. Even in that area, jumbo frames are very rarely used for a simple reason: unless EVERY device in the network supports jumbo frames with the exact same frame size, using these frames causes more harm than good and in fact will make performance worse, not better. At this point very, very few consumer devices support jumbo frames at all and any device that is 10/100 CANNOT support jumbo frames. Heck, a lot of the data center gear doesn't support jumbo frames well and we are starting to use 10Gb/s Ethernet more and more. Here's why jumbo is just a bad idea and more trouble than it is worth:

Let's say the ReadyNas supports jumbo frames but the EVA does not. The EVA requests a file from the ReadyNas to play it, using standard 1500-byte frames. The ReadyNas has jumbo turned on and responds with 9000-byte frames. Depending on the switch, one of two things will happen. Either the 9000-byte frames will be sent on to the EVA where they will be dropped with an error due to the lack of jumbo support, or the switch will be forced to perform frame segmentation, chopping the 9000-byte frames into 1500-byte frames. This can cause a LOT of load on the switch, reducing performance. The EVA is still running on 1500-byte frames anyway, so no performance gain has been realized.

I'll also point out that jumbo frames are NOT an official Ethernet standard and it only takes one vendor to disagree with another on what frame size to support and the whole network can start having problems.

Last, but certainly not least, the performance gains with jumbo frames are mostly illusory. Simple math will show this. Standard Ethernet has a 1500-byte frame with an 18 or 22 byte header (22-byte is only used in environments with VLANs). This results in an efficiency of 98.8%. Switching to a jumbo frame of 9000-bytes only increases the efficiency by 1% to 99.8%. We're not talking about a breakthrough in performance here. The reason jumbo frames were invented had exactly nothing to do with throughput. Instead, they were invented to reduce CPU utilization at high throughput (you process 6x the data for each CPU interrupt with jumbos, which was a big deal back in 1999 when gig-E was first going into wide use). Modern NICs perform a variety of offload techniques to reduce or eliminate these CPU utilization issues (and CPUs have gotten just a tad faster in the last 10 years). I have seen 950Mbits/s achieved routinely on gig-E without jumbo frames. The quality of the end-point gear, cable plant, and switch are far, far more important to performance than frame size.

Bottom line, there is essentially no good reason to use jumbo frames in a consumer environment and a lot of reasons to avoid them.

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So, do you have any ideas as to why this Dell 2724 PowerConnect gives me fits? The $99 (retail at Best Buy) 8 Port Commercial Grade Linksys 10/100/1000 switch works great, the Dell 2724 doesn't. Is the switch junk?

I haven't had a chance to go home and access the admin page on the switch to look at duplex settings like dgbrown suggested. I'm curious though to hear your opinion on why I get such poor performance out of this switch, and not the other?

Thanks for the insight, as I already mentioned I am not a networking guy at all.

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So, do you have any ideas as to why this Dell 2724 PowerConnect gives me fits? The $99 (retail at Best Buy) 8 Port Commercial Grade Linksys 10/100/1000 switch works great, the Dell 2724 doesn't. Is the switch junk?

I haven't had a chance to go home and access the admin page on the switch to look at duplex settings like dgbrown suggested. I'm curious though to hear your opinion on why I get such poor performance out of this switch, and not the other?

Thanks for the insight, as I already mentioned I am not a networking guy at all.

A duplex mismatch absolutely can cause a problem like this. You already tested the most common problems by replacing the cables and the switch itself. Also, avoid the common mistake of being too quick to poo-poo the performance of the Linksys switch. From an engineering stand-point with regard to performance, very little separates the Linksys from that model of Dell switch. If this Dell came from eBay it likely came with the configuration of the previous user (they probably did not do a reset to factory prior to shipping). If the port has been set to an incompatible setting it could have a major impact. Did you try using different ports on the Dell for the various devices? For a gig-e switch, the best setting to use on duplex and speed is auto-negotiate. The Ethernet standard does not support hard-coded speed and duplex for gig-E (though Cisco is notable for ignoring this and other Ethernet standards when convenient). Also, gig-E only exists in full duplex mode. But, for devices that are 10/100 the story is different. Start with auto-negotiate as the default setting. If you encounter problems, attempt to change the end-point to a hard setting of 100 Full-duplex. If this does not resolve the problem, change the switch port to a hard setting of 100 Full-duplex. Getting access to the admin interface will help you a lot, as you can see what the devices are negotiating to for speed, duplex, and flow control.

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Teh D...do you think it would be a good idea to simply do a factory reset on the switch?

That seems easier than doing all this other diag...maybe I am just being lazy...

If you have the directions to do so, absolutely. That should be the first step for any gear picked up used unless you are extremely familiar with it and comfortable with its provenance.

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Teh D...do you think it would be a good idea to simply do a factory reset on the switch?

That seems easier than doing all this other diag...maybe I am just being lazy...

If you have the directions to do so' date=' absolutely. That should be the first step for any gear picked up used unless you are extremely familiar with it and comfortable with its provenance.[/quote']

I'm trying to figure out how to do that for sure right now....instructions on that are actually difficult to find, but I think I've found them.

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Schrader' date=' just bought a used Dell Powerconnect 2724 on eBay for $70. Thanks for the suggestion!

Hopefully it works out.[/quote']

That is the same switch I'm using, no problems at all, be sure to enable jumbo frames

Wingzz, thanks for the tip, how do I do that? I got all my gear rack mounted this weekend, including that switch. I hadn't used it yet, and everything seemed fine until my wife tried watching a movie...it would just buffer and say network performance insufficient. I ran a network test and instead of getting a consistant 60+ mb/s like before it was in the 30's. I tried replacing the cable between the media player, and the cable between the NAS...neither fixed the problem. I put my 8 port Linksys commercial grade 10/100/1000 switch in and everything works like it used to. Does it sound like enabling Jumbo Frames would fix this problem?

Thanks.

I run SoHo junk and Write= 255Mbps / Read 330Mbps here. Thats remote desktop-to-media NAS trip.

Looks like I have about 41mb/s read bandwidth- is that right? If so, your 60 looks very good.

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Well, I'm really at odds about what to do with this switch. I found somewhere online that said I could reset it by holding down the "Managed Mode" button, but that didn't seem to do anything. I cannot figure out what the IP address of the switch is. The documentation I found online suggests it is 192.168.2.1, but that doesn't work. I cannot figure out how to connect to the GUI/admin page of the switch, so I don't have any idea as to how to look at these settings.

Sounds like I need to go find a Dell Network switch forum....any suggestions?

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pressing the Managed Mode button causes:

• Factory default configuration (192.168.2.1) is set as the switch IP address.

• Subnet mask changes to 255.255.255.0

• Graphical User Interface (GUI) login user name changes to Admin, and the password is not

configured (appears blank), with Read/Write privilege.

• The DHCP client is set off.

• The device is rebooted.

1) Sounds like after you do this you will need to set the IP address on your workstation or laptop to an IP address on the same subnet: 192.168.2.10 as an example.

2) Plug the computer into one of the ports on the Dell switch.

3) Then fire up a browser and goto http://192.168.2.1

Not sure you performed steps 1 and 2 above.

Let me know.

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I did not perform step one. I'll do that tonight.

yes your computer and the device your trying to attache to must have the same ip up to the last octet, ie 192.168.2.X the X can be whatever (as long as it is out of the DHCP range) and the subnet mask have to match 255.255.255.0 or whatever it is on both devices

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I did not perform step one. I'll do that tonight.

yes your computer and the device your trying to attache to must have the same ip up to the last octet' date=' ie 192.168.2.X the X can be whatever (as long as it is out of the DHCP range) and the subnet mask have to match 255.255.255.0 or whatever it is on both devices[/quote']

Not mentioned specifically, but X can not be 1, the host address of the factory reset switch either. Nor can it be the host address of any other device on the 192.168.2.X network. If you want to make it easy, just unplug everything from the Dell switch except your workstation with the statically assigned IP address on the 192.168.2.X subnet.

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wingzz

The doc as I read it and clipped in post #40 indicates the dhcp client is disabled and the ip is set to a static 192.168.2.1 .

So in answer to your question, regardless of your network topology (layer 2, 3 or otherwise), upon factory reset the switch will have an IP address of 192.168.2.1.

Dave

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wingzz

The doc as I read it and clipped in post #40 indicates the dhcp client is disabled and the ip is set to a static 192.168.2.1 .

So in answer to your question, regardless of your network topology (layer 2, 3 or otherwise), upon factory reset the switch will have an IP address of 192.168.2.1.

Dave

Thanks

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^ BTW, that's not to say you can't change it (or the vlan configuration, etc) once you make your initial connections to the switch. In fact I'd recommend changing it - if you happen to vpn into your network from another network left on the default (which is sometimes the unroutable .1 network) you can run into problems depending on the vpn client (checkpoint for instance).

Just thought I'd mention that ....

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Thanks guys. When I get home tonight I will either plug my laptop directly into the Dell switch, or I will move one of the other PC's into the house onto the Dell switch, then assign a static IP address of 192.168.2.10, and a subnet mask of 255.255.255.0.

I'll then open up internet explorer and type in 192.168.2.1, and then should be able to login using the username "admin", and no password, correct?

I'll do as suggested and make sure everything is defaulted, and set to full duplex.

I do know that the gear in my house currently has static IP addresses in the 192.168.1.200 - 220 range, with a subnet mask of 255.255.255.0 and a default gateway of 192.168.1.1. Will I need to change all those once I get this new switch working, or will they still be fine? Everything will be ran through this switch.

Thanks!

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Once you gain access to the switch using the default 192.168.2.1 IP address, you may be able to change the switch address to a 192.168.1.x IP address. I know you can do this with routers as I did it when I set up a router to act as a wireless access point on my network.

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Dan Says: I'll then open up internet explorer and type in 192.168.2.1, and then should be able to login using the username "admin", and no password, correct?

Dave Says: Sounds perfect !

Dan Says: Will I need to change all those once I get this new switch working, or will they still be fine? Everything will be ran through this switch.

Dave Says: They'll be fine. I'd recommend changing the IP address of the switch so it's on the 192.168.1.x network along with the rest of your gear. Perhaps an address of 192.168.1.2 (the next address after your router/default gw) or you can go high 192.168.1.254 ... your call.

This way you can connect the rest of the equipment to the Dell switch, use the management interface on the switch, and the management interfaces of the readynas and eva - all at the same time. This will enable you to troubleshoot and if necessary change the interface settings.

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