Hello Gavin Han,
The F1/F2 cards provide layer 2 functionalities such as connect to FEX, directly attach servers, vPC, fabric Path, FCoE, trunks, swicthport and so on. When a layer 3 packet comes it just handles it as a regular switch, the main difference is the the M cards where created to support most L3 funtionalities such as MPLS, Routing protocols and so on.
Though now the F3 card does L3/L2 as well from routing protocols, MPLS, Fex and so on, so this is mostly the recommended option if you want to have both.
A couple of years ago you would create a VDC for Data Center with F cards, VDC for edge OTV device with M cards to expand with OTV L2 over another DC, basically a DCI.
Now with VXLAN EVPN supported in F3 cards, the M cards are not that used anymore.
So to answer your questions:
How to select M and F cards?
- Based on the needs of your companies´ DC, whether you are migrating from a 6K, or migrating from old LCs to the newers, you should see this matrix that has the whole compatibility:
https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/nexus7000/sw/matrix/technical/reference/Module_Comparison_Matrix.pdf
Can we use in combination?
Yes, You can use combination of M cards and F cards on the same chassis, but you might want to know is they have "interoperability within the same VDC", please find in the above link a section called "LC Interoperability (same VDC)", which shows the supported scenarios.
if F card is L2 only then what does it mean when L3 packet comes?
- It can take L3 packets with no problems, where it could have problems is if you want to handle a routing protocol neighborship to one of the Interfaces of the F card or MPLS and features like those, it would not even take the commands. The F3 card supports routing protocols with no problems.
Check the matrix I just provided to you, its really how you can design which LCs works for you and also the interoperability.
Keep us posted,
Please qualify all of the helpful answers!
David Castro,
