using fiber to copper converters on a switch

[ja1064]

we intend to replace a old Cabletron MMAC hub that has a fiber card (ST) that connects to 7 buildings on our campus. We also intend to replace the 10base hubs in the 'remote' buildings with switches.

one option is to buy a fiber switch to make the connection to these buildings

but is there anything bad about using a 3548 with a 100base-fx to 100base-tx converter (both Allied and Transition make them).

that way the same 3548 that will handle the runs in the main building will handle the connections to the other buildings?

[paumercier]

only issue is an addition point of failure, I have to do this type of lash-up all the time, not my favorite way to solve the problem but it works fine.

[ja1064]

so there can't be an argument of any kind of significant performance degradation for example?

and in this case, going from a flat 10base to all switched, the relative improvement would far outweigh any theorectical disadvantage.

[konigl]

From personal experience, there is no noticable degradation of performance, using Transition Networks media converters versus manufacturer-provided 100FX connections. I ran tests years ago with Cisco 2924C XL switches, and with 3Com SuperStack II 3000 and 3300 switches with 100FX modules. Cisco to Cisco, 3Com to 3Com, Cisco to 3Com, both through the manufacturer's own 100FX ports and through Transition Networks Fast Ethernet media converters. Could not measure a statistically significant difference in one switch port and out the one with fiber. (All switches were configured to use "store-and-forward" versus "cut-through" switching, for purposes of benchmarking. This was just to test the throughput of one connection over fiber, not the whole switch. )

We have lots of K-12 schools running 100-megabit full duplex links between buildings over dark fiber, 2 to 20km, no problem. Also have several ISPs sending 100-megabit full duplex feeds to customers, out to 40km, no problem. (The ISP controls and monitors the bandwidth in the Cisco 10/100 Ethernet port at their end.) One of our customers has a 100-megabit full duplex feed carrying Internet2 traffic over a 75km point-to-point link, no problem at all.

The flexability and versatility of the media converter approach far outweighs the additional point of failure, in my opinion. Buy a few spares, or implement some redundant links (HSRP, STP, or FEC), if you want to protect against failure.

And if you connect central switch over fiber to remote hubs, put bridging media converters out with the remote end so your fiber span can run at full duplex. (Remote switches and central switch can just use the regular media converters.)

Hope this helps.