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L2 VLAN tagging supports CoS which many L2 manageable switches can use to treat some application traffic differently from other application traffic. You would need to correctly tag your traffic and configure your switches to process it differently.
You should also insure packets have the L3 ToS byte tagged too. You can often use the L3 ToS byte to set L2 CoS, as needed, and sometimes you can directly treat traffic differently on some "enhanced" L2 switches using it.