Fabric Interconnect & FEX Physical Connectivity !!

[andyblada1]

Hello Team,

I started working on UCS since few months and never get chance to explore the UCS H/w and its connectivity.

Due to which i have a confusion on SFP-10G-SR Module and twinax cables.

Does connectivity between FI A,B and FEX 2204 requires SFP-10G-SR Module + Twinax cables??

OR

Only twinax cables ( i.e SFP-H10GB-CU1M, 3m , 5m which be default comes with SFP+ connector).

Means to say that these cables are coming with SFP+ connectors no need to buy separate SFP modules with them.

Which can directly connects FI to FEX?

Please put some light on it !! 

 Cheers!

Andy 

[Walter Dey]

Hi Andy

Twinax is a low cost 10G connectivity solution, which is very limited in distance (to achieve the required BER of the 10G standard).

Typically, it is used in UCS between IOM in the chassis and the FI.

If you need longer distances (>10+-m), your choice is fibre, which requires a SFP+ on either side of the link; cost is factors higher than twinax.

Northbound of FI one would typically not use FEX, which would increase oversubscription; 10G wirerate is best practise.

If you need to attach a lot of rack mount servers to FI, FEX might be a solution;

see also

http://www.cisco.com/c/en/us/support/interfaces-modules/transceiver-modules/products-device-support-tables-list.html

Walter.

[andyblada1]

Thnx Walter for explanation!!

But my main concern on how cable looks .

Is twinax Copper Cables and Active Optical Cables are by default comes with SFP+ connector.

Or do i need to order separately SFP-10G-SR Module.

Lets take an example.

If i am preparing a BOM with one chassis 5108 with a pair or FI 6248 & FEX 2204 with 4 link policy.

Which and how many cable & modules needed??

8 Twinax only. or 8 twinax with 8 SFP-10G-SR Modules??

Cheers

Andy !!

[Walter Dey · Accepted solution]

Hi Andy

For the cabling of your chassis to the FI's, you need 2 x 4 twinax cables, most likely rather short (max 3m), because your chassis and FI's are in the same rack. No SFP's necessary !

For the external connection (North bound) from FI to your switch, this is most likely based on fibre, therefore you would need optical transceiver on either side; the fibre cable doesn't inlcude those.

Hope this is clear ?

Walter.