gbic question

[rugby15ace]

I'm a little confused about the gbics and full duplex. Reading the cisco info on gbics it states you can connect point-to-point full duplex or 8 half duplex. Does that mean you can have one point-to-point and then cascade 8 more switches in half duplex? Second, can you just daisy chain full duplex or do you have to connect in a star configuration for more than two switches? Thanks for the help.

[Georg Pauwen]

Hello,

your assumptions are right: you can only have one point-to-point in full duplex, the cascaded switches only support half duplex. In order to get full duplex connections to all switches, you will have to build a star, using an aggregation switch such as the 3550-12G switch.

HTH,

Georg

www.solutionfinders.nl

[rugby15ace]

Ok, if I set up 9 switches cascaded, then could I use the other gigabit port and cascade it to the same 9 switches and etherchannel them to get a higher throughput and redundacy? Thanks.

Alan

[marvin]

With a cascade connection, the GigaStack GBIC creates a half-duplex repeater bus external to the switch fabric of the individual switches.

With a star configuration (or individual point to point) you can have full duplex.

1. 3 Switches A, B, C - Cascade

All three switches have a GBIC in the first slot. In a cascaded configuration, you will have half duplex from A to B, B to C, and C to A.

2. 3 Switches A, B, C - Star

Switches A and C have a GBIC in the first slot, switch B has a GBIC in both slots. Switch B has one GBIC connected to Switch A, and one GBIC connected to switch C. Switch B has full duplex connections to A and C, but any traffic from A to C has to transit switch B's backplane.

Additional Reference:

Cisco GigaStack GBIC -

http://www.cisco.com/en/US/products/hw/modules/ps872/products_data_sheet09186a00800a1789.html

[rugby15ace]

Thanks for your help. I'm not really sure what you mean when you say transit switch B's backplane? The document mentions that it doesn't have to transit the switch's backplane in cascade, also. If a packet starts from switch 1 and goes to switch 9, how does it not go through the other switches? Are we talking about the tables used? Sorry for so many questions. Thanks again.

Alan