The 2600 series by default, enumerate VLAN Mac-Addresses in the order they are created.
VLAN 1 (The default VLAN) Has the base Mac of the switch :00.
The next VLAN created will be assigned :01 and the next VLAN :02 and so on.
It really is the order in which the VLANs are instantiated on the switch that determines the Mac address assigned.
For example:
conf
vlan 3
vlan 2
Will assign :01 to vlan 3 and :02 to vlan 2.
But if you then rebooted the switch, you'd find vlan 2 had been assigned :01 and vlan 3 had been assigned :02.
Because the switch would instantiates the VLANs in Ascending order on startup.
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Just to confuse things a bit more, if you set max-vlans to a value greater than 32. The switch assigns all Mac-Addresses the Base-Mac of the switch.
Firmware Branch Max VLANs Incrementing?
F 30 Yes
H 253 Mixed Yes if max-vlans <= 32, No if max-vlans > 32
Q 64 No
R 256 No
E 256 No
K 2048 No