[j-nsp] Redundacy

[sunnyday]

Hello all
I want to configure two interfaces facing the subscribers with the link selection primary and 
link selection secondary  commands and i want to know the behavior of this and how can i use it
i want as it semms if 2/6 fails 2/7 to terminate ppp but if both are up what will happen?
isnt there going to be a problem for vlans when there is a bulk config at two interfaces?
thanks
the conf is something like that:

interface gigabitEthernet 2/6
 mtu 1522
 duplex full
 speed 1000
 link failover timeout 500
 link selection primary
 qos-profile test
 encapsulation vlan
 auto-configure vlan
 vlan bulk-config "vlan-bulk"
 profile vlan bulk-config "vlan-bulk" "vlan-generic"
 vlan bulk-config "vlan-bulk" vlan-range 100 199
 vlan bulk-config "vlan-bulk" vlan-range 2101 2199
 vlan bulk-config "vlan-bulk" vlan-range 3401 3499
=======================================
interface gigabitEthernet 2/7
  mtu 1522
 duplex full
 speed 1000
 link failover timeout 500
 link selection secondary
 qos-profile test
 encapsulation vlan
 auto-configure vlan
 vlan bulk-config "vlan-bulk"
 profile vlan bulk-config "vlan-bulk" "vlan-generic"
 vlan bulk-config "vlan-bulk" vlan-range 100 199
 vlan bulk-config "vlan-bulk" vlan-range 2101 2199
 vlan bulk-config "vlan-bulk" vlan-range 3401 3499