But in reth interfaces, one interface is taken from the primary chassis and other is from the standby and both physical interfaces are combined into a reth group.
But in Red interfaces in netscreen, 2 physical interfaces are coming out of the same firewall and goes to the different switches. And one interface remains active at a given time while other remains in the backup mode. So if one interface in the redundant goes down firewall does not switchover it just start forwarding to other switch.