In PVlan, the Primary Vlan looks like a normal vlan for other normal vlans on the switch. You can see this from the 'show vlan' command. For eg. vlan 100 is configured as the primary vlan in a Pvlan and 300 as the seconday vlan (isolated) for this Pvlan. Ports 3/1 and 3/2 are configured as isolated ports by assigning them to vlan 300 and port 3/14 is configured as promiscuous, you will see the folowing :
catalyst> (enable) show vlan
VLAN Name Status IfIndex Mod/Ports, Vlans
---- -------------------------------- --------- ------- ------------------------
1 default active 5 1/1-2
3/3-4,3/6-12,3/15-48
100 VLAN0100 active 88 3/1-2,3/14
300 VLAN0300 active 89
1002 fddi-default active 6
1003 token-ring-default active 9
1004 fddinet-default active 7
1005 trnet-default active 8
catalyst> (enable) show pvlan
Primary Secondary Secondary-Type Ports
------- --------- ---------------- ------------
100 300 isolated 3/1-2
catalyst> (enable) show pvlan mapping
Port Primary Secondary
---- ------- ---------
3/14 100 300
So, I think the primary and secondary vlans are visible only within the Pvlan, and the Pvlan looks like a normal vlan for other vlans. You can assign a port either to seconday, primary or normal vlan. They cannot belong to more than one of these vlans. Hence, the gateway connected to promiscuous port would like like it is connected to a normal vlan for other vlans, and would look like a primary vlan for the seconday vlans of that Pvlan. You can refer this document for more information :
http://www.cisco.com/warp/customer/473/90.shtml
