Note: Attached is the network diagram
In the diagram you will see that two links goes to the VOIP switch (SG switch)
From 2960:
interface FastEthernet0/6
description ** FIOS to Evolve Switch **
switchport mode access
interface FastEthernet0/20
description ** TW to Evolve Switch **
switchport access vlan 103
switchport mode access
From VOIP switch:
interface gigabitethernet1/21
description FIOS
switchport mode access
switchport access vlan 3
!next command is internal.
interface gigabitethernet1/22
description TimeWarner
switchport mode access
switchport access vlan 3
!next command is internal.
This setup makes both the Primary and the backup operational ( i can ping both public IPs)
When we made the test to disconnect the Primary, it did not failover to the backup. they lost their phones.
After that we tried change the port configuration of 2960 switch:
int fa0/20
switchport mode trunk
switchport trunk native vlan 103
switchport trunk allowed vlan 102,103
int fa0/6
switchport mode trunk
switchport trunk native vlan 103
switchport trunk allowed vlan 102,103
This setup made both lines unoperational.
Removing the VLAN tagging of one of the ports will make the other Line operational. It never works while both of the ports have tagging.