Communication Manager creates Inter-Gateway Connections (IGCs) to convey the IP streams. The G450 and G430 Branch Gateways provide both source ports and sync ports for the IGCs. CSoIP supports TDM-based devices, such as an H.320 video device to retain and transmit within an IP infrastructure. You administer Clock Synchronization over IP through the Communication Manager's SAT Administration forms.

Instead of DS1 or BRI interface, you can use a local clock as the clocking source. You can choose a primary and any other backup sources.

The Communication Manager maintenance object and connection manager create and maintain the synchronization domains, also known as sync domains. A sync domain is a clock source that emanates IGC streams to clock receivers. All gateways involved with the CSoIP feature are referred to as members. A master domain is a clock source derived from a DS1 or BRI, which is used to emanate IGC streams to clock receivers. Other members that use the incoming IGC stream for internal clocking are known as slave clocks. The receiver is one hop level below the clock source. A secondary clock domain uses the incoming IGC stream, which is used to clock outgoing IGC streams to other members.

Depending on the limitation of the fan-out, a single clock source cannot source a stream to the maximum number of gateways. As a result, some clock receivers also become clocking source, known as the secondary clock source. These, in turn, constitute sync domains.

When the first IGC source comes into service, it becomes the default system clock source. All other IGC sources become slaves until the fan-out limit is reached. After the fan-out limit is reached, a slave is promoted to a secondary clock source, known as a tandem clock. Subsequent receivers are then clocked from the secondary source until its fan-out is reached. Then another slave from that sync domain is promoted to a tandem clock. This process takes place as each clock source reaches its fan-out limit.

When a master clock board comes into service, it is used to create a master clock domain if there is an IGC source board already providing IGC streams. The highest level clock source that was the default system clock source is demoted and becomes a receiver of a master clock source and becomes a tandem clock. There can be as many master clock domains as there are administered sync sources.

The CSoIP feature does not attempt to mitigate the reference board outages. If such a board goes out of service, the traditional sync feature raises an alarm and you need to rectify the problem. Removing or adding any reference board from translations causes the CSoIP feature to adjust to move members to another source or begin adding members to the new source.

There can be several DS1s, BRIs, or other boards capable of providing a reference from the PSTN, and each can be used by the CSoIP feature to provide sync to a group of members.