3550 w/ Gigastacks

[jtarbox]

If I - for instance - setup a stack of 4 3550 switches with Gigastack GBICs, is the other GBIC port in all four switches available for use? Can I put in 4 1000bSX modules for instance and uplink to other switches and servers?

[konigl]

Yes.

The four 3550 switches cascaded with GigaStack GBICs will be sharing a Gig Ethernet backbone that runs at half-duplex. The use of GS GBICs in "interface Gig0/1" does not preclude you from using other GBICs in "interface Gig0/2" of each switch.

Feel free to plug in 1000BASE-T, SX, LX/LH, or ZX GBICs for point-to-point connections to other switches or servers.

I suppose you could even use GS GBICs again, and run secondary GigaStack cascades off these. But if you were already close enough to use GS GBICs, it would probably be better to just extend the primary GigaStack cascade first, to the maximum of nine switches.

Hope this helps.

[jtarbox]

What about in the case of a 3550-12G? Can I put in 12 Gigastacks and link 12 switches to it? Or am I limited to just the 9?

[konigl]

3550-12G has 10 GBIC slots, and two fixed 10/100/1000 ports. In theory, you could put a GS GBIC in each of the ten GBIC slots, and cascade 8 more switches with GS GBICs off each of them. The 3550-12G would then be the 9th switch on each of those 10 GS GBIC cascades.

In practice, it might be a little difficult to physically locate 80 stackable switches within connecting distance using just the 50cm cables that come with the GS GBICs. Although you could probably do it if you purchased a lot of the 1-meter GS cables, and interleaved the cascaded switches.

[richgodfrey]

Or you could use 1000Base-T GBICs in the 3550-12G and your access switches. This would be 1000 MBit/s full duplex to each switch, and overcomes the 1metre distance limitation of Gigastack cables.

To stack 12 switches into the 3550 you could only need six Gigastacks if you don't want redundancy. (Two ports per Gigastack card)