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New Member

Assistance choosing the right switch models

The design is for a fiber aggregation switch (at least 8 ports) in the MDF, 4 seperatly located (4 different IDF's) 24 port switches with at least 1 fiber port. These switches are access level, with low expected usage. No QoS, no VLAN's needed.

So I'll need 5 total switches, one is the aggregation switch, four feed into that switch via fiber.

Any assistance is appreciated.


Re: Assistance choosing the right switch models

I don't know if you need copper ports in the MDF; or if your servers will be connected via the MDF. Or how many you have, etc. (So many unanswered questions!) But if I were looking to keep the cost down while providing a fair amount of flexibility, I would recommend the following based on what you've written so far:

For the MDF, a switch that aggregates four fiber feeds, and provides local 10/100/1000 copper ports for servers or workstations.

Quantity: 1

Product Number: WS-C3750G-24TS-S

Description: Catalyst 3750 24 10/100/1000T + 4 SFP Standard Multilayer

Cost: US$6,995 list.

Quantity: 4

Product Number: GLC-SX-MM=

Description: GE SFP, LC connector SX transceiver

Cost: US$500 list each; US$2,000 total.

And for the four IDFs, each one gets a low-cost 10/100 copper switch with a Gigabit Ethernet fiber connection back to the MDF.

Quantity: 4

Product Number: WS-C2950G-24-EI

Description: Catalyst 2950, 24 10/100 with 2GBIC slots, Enhanced Image

Cost: US$2,495 list each; US$9,980 total.

Quantity: 4

Product Number: WS-G5484=

Description: 1000BASE-SX Short Wavelength GBIC (Multimode only)

Cost: US$500 list each; US$2,000 total.

Total cost of the switching equipment, excluding fiber patch cables: US$8,995 for the MDF, and US$11,980 for the four IDFs. Which adds up to US$20,975 for the whole thing.

If you do not need copper ports in the MDF, you can change the specification of the fiber aggregation switch there to a Catalyst 3508G and the four SFPs to GBICs, shaving another US$2,000 off the MDF equipment price.

How does this sound to you? To me, it still seems a little pricey, given that you wanted just a simple, flat, fast network. Then again, these are list prices.

However, these are the least expensive switches available from Cisco that meet your requirements. Even though you don't need VLANs or QoS, those capabilities are included anyway.

Hope this helps.

New Member

Re: Assistance choosing the right switch models

Thanks, that's the right info. Yes I need copper in the MDF so I'll stick with the top recomendation.

Do you know if Cisco makes a fiber to 10/100 ethernet stand alone converter?


Re: Assistance choosing the right switch models

Well, you could use one of Cisco's low-end switches with a 100FX port to do this:

Product Number: WS-C2950C-24

Description: 24 10/100 ports with 2 100BASE-FX uplinks, Enhanced Image

Cost: US$2,195 list

But that's an awfully expensive media converter.

Transition Networks ( manufactures media converters in a variety of configurations. They're sure to have something that fits your requirement. The one(s) you probably need sell for something like 10% to 20% of --not off-- the cost of that Cisco switch.

If it will be used to connect a switch, just go with a 100BASE-TX to 100BASE-FX converter.

Make sure you match up the fiber optic connector type (ST, SC, etc.) and the fiber type (multimode or single mode), and run the link in full duplex for best performance and maximum distance. Fiber at half duplex is limited to 412m; full duplex is good to 2km on multimode, and out to 20, 40, 60, or even 80km on single mode, depending on which converter you use.

If it will be used to connect a shared media hub or other device which cannot operate in full duplex mode, then look at their 10/100 bridging media converters.

The 10/100 port faces the device(s) that cannot operate at full duplex. (Think of it as a "mini-switch".) You can back-end that 10/100 bridging media converter on the far end of the fiber with a regular 100BASE-FX to 100BASE-TX media converter (costs a little less than the bridging one), since the 10/100 bridging converter will run full duplex on the fiber side.

Hope that helps.


Re: Assistance choosing the right switch models

I don't mean to hijack the thread, but I would like some clarification.

Using WS-C2950G-48-EI Catalyst 2950, I would also need a WS-G5484 1000BASE-SX to connect back to a MDF switch?


Re: Assistance choosing the right switch models

Oh no, we've been hijacked! (Just kidding.)

Yes, the SX GBIC is what you need to connect the Catalyst 2950G-48 at Gigabit Ethernet speed, over multimode fiber cable less than 220-275m, and there are open Gigabit Ethernet SX switchports in the MDF. SX GBICs transmit at 850nm wavelength.

If you must connect at Gigabit Ethernet speed on multimode fiber and the distance is greater than that listed above but less than 550m, then you would need the WS-G5486 1000BASE-LX/LH GBIC at each end instead. Also, you would need to use mode conditioning patch cables at each end. These are specialized hybrid multimode/single-mode patch cables, designed to give the 1300nm wavelength transmission signal an offset launch into the multimode fiber span.

If you must connect at Gigabit Ethernet speed on single mode fiber instead of multimode, at distances less than 10km, then you definitely need the LX/LH GBIC at each end. But you don't need mode conditioning patch cables: single mode patch cables are what you want.

If your MDF switch has 100BASE-FX Fast Ethernet ports instead of Gigabit Ethernet, then none of the above-mentioned GBICs will work. (Although you would get a link light if you use the LX/LH GBIC, because it operates at the same 1300nm wavelength as 100BASE-FX.) You could, however, use a 100BASE-FX to 100BASE-TX media converter to connect to one of the 10/100 ports on the Catalyst 2950G-48. There are several companies that make these; I use the ones manufactured by Transition Networks. Follow the links to their website in my previous post to this thread/conversation.

Hope this clears things up.