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thinking about adding switch.. some advice please

Last response: in Networking
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February 2, 2006 6:27:57 PM

Current setup:

Moto cable modom --> netgear FR114P (10/100)router --> 4 PCs. I need to add a 5th and the router is only 4 ports. If I throw a switch into the mix (thinking about netgear gs108 which was reviewed here) I'm assuming I can just use a crossover cable and uplink it to my router. It's a gigalan switch but I'm thinking it won't work with my router since the router is 10/100.

modem --> router ---> switch --> 5 PCs?

Do I have that right? Can everything behind the switch be gigalan AND the router to switch be 100? How does assigning IPs work if so? Does the switch function as a DHCP? How about port forwarding?

Thanks all.
February 2, 2006 10:58:46 PM

When you connect the switch to the router, that port will share the bandwidth. Max will be 100 from router to switch. If you connect 2 computers to the switch, they can comunicate to each other at 1 gig? (not sure, maybe controlled by the DHCP router), but only 100 to router. If both access the router, band width will be 50%.

You shouldn't need a crossover cable, it should auto select.

I have a 8 port router for the same reason. 3 pc, 1 mac, 1 Snap2200 NAS, 1 HP4100DN printer, and 1 AP. 1 spare. I have a 8 port switch connected where the AP is at, for hardline if needed.

Generaly if you share a port, you would like equipment that is not in continues use.
February 3, 2006 5:47:37 PM

OK... I'm not too worried about sharing the bandwidth from the cable modem, just the PC behind the switch. I have two questions:

1) How does port forwarding work with a switch? The router still assigns the IP addresses, right? Therefore port forwarding that is setup in the router should still apply. Am I correct in this?

2) I'd like the PCs to be able to take advantage of the gigalan speed AND have the ability to use the internet (WAN) without changing settings. Can I operate a gigalan switch @ 1000 MBit that's hooked up to a 10/100 router (no jumbo frames)?

Thanks all!
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February 3, 2006 6:20:06 PM

I don't know much about port forwarding. I don't think you will be able to use your gig lan. It will proably drop back to 100 because the router controls the DHCP and port forwarding.
February 3, 2006 8:07:24 PM

You got the topology correct. Your Gigalan should be autosensing 10/100/1000. I've never seen anything that is 1000baseT that isn't 10/100/1000. Configure your router to be your DHCP server. On the router, the FR114p, it will just maintain a forwarding table and forwards all PCs on the switch out the port that the switch is connected to on the router. Port forwarding will work exactly the same way it does if there were no switch there. Remember the switch isn't a layer three device. You will have bandwidth contention issues on the router and switch link should you be able to generate enough traffic to notice.
February 3, 2006 10:00:30 PM

Just connect in the switch with either normal or crossover CAT5 cable. The GS108 ports are all auto MDI / MDI-X and will make the connection just fine.

The switch will be invisible to the router and everything will work just like it was connected to a router port.

el0him is correct that if you have gigabit NICs then they'll run just fine along with any machines that have 10/100. Jumbo frames, however, WON'T work because the router won't know how to deal with them for Internet bound traffic.
February 3, 2006 10:08:36 PM

Quote:
el0him is correct that if you have gigabit NICs then they'll run just fine along with any machines that have 10/100. Jumbo frames, however, WON'T work because the router won't know how to deal with them for Internet bound traffic.


So does that mean that if all the PCs behind the switch are running with gigalan cards, they will talk to eachother @ gigalan speeds? As well, the router will talk to the switch at 100 Mb? ...or does the entire setup drop down to match the slowest link?

What if only 3 of 5 PCs use gigalan (other two are 100). Does the switch serve up packets to the 3 @ 1000 and the other 2 @ 100?
February 4, 2006 8:26:23 PM

Quote:
So does that mean that if all the PCs behind the switch are running with gigalan cards, they will talk to eachother @ gigalan speeds? As well, the router will talk to the switch at 100 Mb? ...or does the entire setup drop down to match the slowest link?

What if only 3 of 5 PCs use gigalan (other two are 100). Does the switch serve up packets to the 3 @ 1000 and the other 2 @ 100?

Each port on a "gigabit" switch can deal with Ethernet NICs running at 10/100 or 1000Mbps and communication speed for each pair of devices is independent of the others.

So 100Mbps machines will run at 100Mbps and gigabit machines will run at 1000Mbps. And when a 100Mbps machine exchanges data with a 1000Mbps machine, the lower speed will determine the transfer rate FOR THAT PAIR OF DEVICES ONLY.
February 4, 2006 10:49:04 PM

Thanks for the info! Just ordered a gs-108 and a trio of 530T's (dlink). Should be fun!
February 12, 2006 10:08:56 AM

Here's a bit I wanted to post as an opinion on this switch, but I get errors when I tried to do it at this URL. I'm pretty happy with it:

Quote:
Make sure your serial number starts with 127 if you are buying this product specifically for its Jumbo Frame support. I have seen a 3-4x boost in throughput (compared to speeds from the 10/100 router) on xfers between machines WITHOUT using JFs. Net Gear makes some good stuff if you buy their "blue box" products like the gs-108. Very good built quality, metal case, etc. Also, the gs-108 is fanless which is a big plus.

I didn't get my GS-108 for the Gigalan to be honest. I needed more than 4 ports which is all my router has so since I had to spend the money to "upgrade" I felt the GS-108 would be a good choice.

Measurements of speed/throughput are crude (stopwatch to the nearest second) and haven't been repeated beyond twice. My network speeds from PC-to-PC seem to be limited by the physical drive as measured by moving a single 300 meg file from drive-to-drive (both SATA I drives) which is about 46 Mb/sec. When I move the same file to and from other machines on my LAN indeed the xfer rates are hit and miss around that number (35-42 megs/sec). Throughout without the switch (through the 10/100 router) was 9-11 Mb/sec. Throughput seems to be the same via FTP and through Windows explorer and SAMBA on the LINUX side.

Throughput drops to around 25-26 Mb/sec when xfering many files going through SAMBA which isn't as lean as FTP. Here are some examples through SAMBA to/from relatively fast machines one with SATA I drives, the other with ATA100 drives:

10 files; 1.36 GB (1,464,032,686 bytes) in 55 sec - 25,995 Mb/sec
12 files; 1.70 GB (1,831,892,992 bytes) in 68 sec - 26,308 Mb/sec

I haven't done the experiment where I move the same dirs through the 10/100 router to compare.

Bottom line: real speed boosts and remember I wasn't using JFs.
February 26, 2006 6:40:21 PM

Here's an apples-to-apples comparison of my FR114P router vs. my gs-108. FTP xfer in both cases, one where both machines were plugged into the 10/100 router, the second where both machines are plugged into the gigalan switch (with standard MTU size frames).

size: 1.19 gigs
time: 110 sec
throughput: 11.0 megs/sec

size: 1.19 gigs
time: 40 sec
throughput: 30.4 megs/sec

That was the average of several runs.
!