Border Gateway Function (BGF) support for high availability for PICs running the pgcpd process

The BGF provides a 1:1 redundancy model for PICs and DPCs that are running the pgcpd process. There is one primary service PIC and one secondary service PIC that acts as a backup. If the primary service PIC fails, the secondary PIC becomes active and H.248 traffic is switched over to the new active PIC. When the failed PIC recovers, it comes up as the secondary PIC. The BGF supports hot standby mode to ensure that failover occurs in 5 seconds or less.