i have the follow dilemma. a 3550XL has a voice vlan 10 , a data vlan 20 and an management vlan 99. assinging the vlan 10 as native wil remove its tagg across the trunk ports. also cisco recomends native vlan not be the same as management vlan . but when i made the vlan 99 the vlan 1 goes in shutdown situation . so what is the best practice about tha native vlan into a voice switch ?