Trunking with 3 switches

[AVAGO]

Hi

I'm sure this has been asked in past but I have not found the exect question.

we have 3 40 8GB sna switches (FOS 7.4.2a. All 3 units have trunking licenses.

So I'm looking for the best way to trunk these all together .

Is this a viable option

switch 1 port35 ---> switch 2 port35

switch 2 port38 ---> switch 3 port35

switch 3 port38 ---> switch 1 port38

so 6 ports across 3 switches each switch having a 32GB trunk

Or is there a more efficient way to trunk the 3 units together ?

any advise gratefully received

[Marian Bezeg]

Hello,

there are more SAN designs based on type which you want to use.

In this case you will use ring/mesh topology which is not best scalable. Its depend on what you want to achive and how many hops you will have between initiator and target (in this config 2 as max)

Please check if you are using same ASIC for one trunk group (you have to use port from same port group 0-7,8-15, etc..)

You can verify it with command:

porttrunkarea --show all

[AVAGO]

Hi Thanks for the reply

    What would be a better option to make it scalable & resiliant  ? the ports used on all switches would be ports 35 & 38  which are in the same  ASIC Trunk Group

Phil

[Antonio Bongiorno T…]

@AVAGO

--->>>we have 3 40 8GB sna switches....

i assume "40" is the port number ? are the switch 5100 ?

if yes, the 5100 is a single ASIC Switch

[AVAGO]

Hi Antonio

   yes the switches are the DS5100 40port with 8GB sfp, below is some of the  output for porttrunkarea

admin> porttrunkarea --show all

Port Type   State   Master   TI DI

-------------------------------------

0   --             --     -- 0

1   --             --     -- 1

2   --             --     -- 2

3   --             --     -- 3

4   --             --     -- 4

5   --             --     -- 5

6   --             --     -- 6

7   --             --     -- 7

-------------------------------------

8   --             --     -- 8

9   --             --     -- 9

10   --             --     -- 10

11   --             --     -- 11

12   --             --     -- 12

13   --             --     -- 13

14   --             --     -- 14

15   --             --     -- 15

What would be the better way to trunk all 3 switches if the Ring/mesh is not efficient ? we have two fabrics each with 3 DS5100's in then the san storage is conneted to both across the switch's available also most of the servers have two or more FC connetions into the fabrics

[Antonio Bongiorno T…]

@AVAGO

Trunk can ONLY! be formed in the same octet 0-7 ; 8-15 and so on

you should not created TWO trunk group in the same octet.

[AVAGO]

Hi Antonio

   Should we only use one port in each Octet

Switch 1 ----> port 0 to Switch 2 ---> port 0

Switch 2 ---> port 8 to switch 3 -----> Port 8

Switch 3 ---> port 16 to Switch 1---> port 16

The method above is Ring,using 6 ports but is this the most efficient way ?

Or is it better  to do it this way using 4 ports ?

Switch 1 --- > Port35  to switch 2 port35

Switch 2 ---> port38  to switch 3 port 35 

many thanks for your input

Phil

[Antonio Bongiorno T…]

@AVAGO

NO!

Trunk must be formed in the same Octet, example:

you create a trunk of TWO port in first octet, at Port 0 and port 1 - or other port as saied beetwen 0-7

the second trunk in another octet beetwen 8-15 and so on.

theoretically ( Trunk consinst at least of TWo Port ) you can create max. 4 Trunk Group in same Octet, each of TWO port, but is recommended to use different Octet.

[AVAGO]

Hi Antonio

   thankyou for your quick response.

I thing I undersatnd what you are saying

Switch 1 Ports 0 & 1  to switch 2 ports 0 &1

so  we would have a 2 port trunk  in the same Octet , but  I have a 3rd switch is this just a case of using ports 35 & 38 on either switch 1 or 2 to trunk to switch 3

I'm trying to understand the best practice to trunk 3 switch's together so in the event of a switch failure the system is still efficient

or is it not a big issue as there are multipul connetions from the san storage split across 2 Fabrics ( with each fabric having 3 switch's )

and the servers have a minimum of 2 connections split across the 2 fabrics

phil

[Antonio Bongiorno T…]

@AVAGO

Since you have a DUAL Fabric, Core / EDGE topology is in you case the best solutions

One 5100 is Core, the both other 5100 will be connected as Trunk as EDGE.

connect the Storage to the Core, and all HOST to EDGE Switches