Adding more switches

Question

Hello,

We currently have 2 brocade 200e switches. We are at the point to where we are running out of ports, and we are in the process of adding 2 more 200e. My question is, is it necessary to "trunk" the switches together? We have a 4Gb end-to-end connection (from the HBA, to the switch, and onto the SAN). What are the benefits of trunking and how it works?

thanks,

joel

RRR · Answer

A fabric is a set of physical connected switches.
First of all you want to keep your 2 fabrics separated to avoid a SPOF, just as you now have.
When you're running out of ports, you decide (per fabric) how much bandwidth you need for the trunk between new switches and the "core". Furthermore is a good idea to decide if in the future even more switches need to be connected to the presebt "core". for example on the 200E with 16 ports, you take 2 ports and ISL them to the new switch. The Brocade switch automatically bundles them into a trunk (with the right license of course). This trunk has 8Gb capacity which is shared with all the 14 ports on the 2nd switch, so if the 1st switch has a Clariion connected with 6 ports and 2 ports trinked to a 2nd switch, all 8 remaining ports on the 1st switch have 6 x 4Gb bandwidth to the Clariion, while the 14 ports (hosts) on the 2nd switch all have to go through the trunk and can only reach 2 x 4Gb (the trunk) = 8Gb to the Clariion.

Hope this helps

odurasler · Answer

Thanks! That was very helpful. Let's see if I understood you correctly.

:The 1st (SW1) and 2nd (SW2) switch are currenlty connected to the clariion with SW1 connected to SPA 0 and SPB 1; SW2 connected to SPA 1 and SPB 0.

:With the addition of a 3rd (SW3) and a 4th (SW4) switch, I have the ability to "trunk" SW3 to SW1 and SW2...and..."trunk" SW4 to SW1 and SW2. Is this correct?

:If I trunked the switches using 2 ports (from the above example), I should get an 8Gb bandwith. I would also lose 16 ports from all switches using this method. Is that correct?

Given this scenario, wouldn't I have a bottleneck anyway to the clariion (from SW1 or SW2) since I only have 1 "ACTIVE" connection?

RRR · Answer

With the addition of a 3rd (SW3) and a 4th (SW4) switch, I have the ability to "trunk" SW3 to SW1 and SW2...and..."trunk" SW4 to SW1 and SW2. Is this correct?

I wouldn't connect everything together, since everything then forms 1 single physical fabric. If you do so, you'll get a SPOF (single point of failure). Connect SW3 to SW1 and SW4 to SW2.

If I trunked the switches using 2 ports (from the above example), I should get an 8Gb bandwith. I would also lose 16 ports from all switches using this method. Is that correct?

The 8Gb bandwidth is for the SW3 and SW4 (oversubscription)

Given this scenario, wouldn't I have a bottleneck anyway to the clariion (from SW1 or SW2) since I only have 1 "ACTIVE" connection?

1 Active connection for each LUN. LUN1 can run on SPA and LUN2 can run on SPB, so both SP's are active, but not for all LUN's.

Connectrix

Adding more switches

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