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Network design

I have to connect network together across a fiber trunk. I would like to know what switch would best for this task and how should I approach it.

Community Member

Re: Network design

Cisco 3508 XL switch can be used to connect fiber connections at Gigabit speeds. You need GBICs SX or LX based on the distance.

I don't know if there is any other cheaper way to do it with Cisco products.

If you are not interested in gigabit you can buy a Fiber to Copper 10/100 Transceiver and use that to convert fiber to copper and connect to a regular 10/100 switch.


Re: Network design

What switches and routers do you have now?

The 3508G is the least expensive all-fiber-capable Layer 2 switch that Cisco makes. But if you need Layer 3 switching or routing capabilities, it's not your best choice.

If you have other switches, you may be able to do Layer 3 with them; and you may be able to use optical GBICs to connect the ones you have. Cisco's 3550's are good ones to look at; the 3750's are also good; if you don't already have something that can do "routing-at-wire-speed".

Media converters can also be a useful way to go: I support several school districts who spent the bulk of their technology budget on fiber between buildings. We installed one cheap Layer 3 switch with 24 10/100 ports to provide default gateway services for all of the remote buildings over fiber, using a pair of media converters on each link. One converter plugs into the L3 switch, the other into a switch in the remote building's main wiring closet. The L3 switch connects to a "server farm" Layer 2 switch locally over a Gigabit Ethernet SX link. Fast, simple to manage and maintain, and best of all for them, cheap. (Cisco, Extreme, and Foundry all have products that suit this purpose.)

If you have access to dark fiber (that is, fiber that is unlit until you put your network electronics on it), then you have two choices for fast and cheap: Gigabit Ethernet speeds, or Fast Ethernet speeds.

Gig comes in SX, LX/LH, and ZX GBIC or SFP varieties; anything longer than 220m to 550m distance and you're talking about LX/LH (out to 10km) or ZX (out to 70 or 100km) over single mode fiber.

Fast Ethernet is good to 2km over multimode in full duplex mode; and Transition Networks makes media converters that are good to 20km, 40km, 60km, and 80km distances over single-mode fiber, conservatively speaking. I have one customer that is getting 100-megabit Internet feeds from two separate ISPs over fiber: one of those runs is 103km, and it works fine.

Hope this helps.

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