[c-nsp] VSS Best Practices

[Ivan]

Cisco VSS best practice document states

Recommendations
    *      Always run L2 or L3 MEC.
    *      Do not use on and off options with PAgP or LACP or Trunk
protocol negotiation.
          o            PAgP — Run Desirable-Desirable with MEC links.
          o            LACP — Run Active-Active with MEC links.
          o            Trunk — Run Desirable-Desirable with MEC links.


http://www.cisco.com/en/US/products/ps9336/products_tech_note09186a0080a7c837.shtml

There is not really any explanation of the reasoning behind these
recommendations.  If anyone can explain the rational that would be great. 
I would also be interested to hear what settings people are using in
production, why and how that is going.

Generally in non VSS setups I have found setting links explicitly to trunk
mode and as etherchannel members has been reliable and would like to
understand why they are not recommended above.

Thanks

Ivan