DSP resources on the Cisco gateway, for example, Catalyst 4000 (WS-X4604-GWY), Catalyst 6000 (WS-6608-T1 or WS-6608-E1), Cisco 2600, Cisco 2600XM, Cisco 2800, Cisco 3600, Cisco 3700, Cisco 3800, or Cisco VG200, provide hardware support for IP telephony features that are offered by Cisco Unified Communications Manager. These features include hardware-enabled voice conferencing, hardware-based MTP support for supplementary services, and transcoding services.
Verify with your Cisco account manager the devices that support conferencing, media termination points, and transcoding services.
The DSP resource management (DSPRM) maintains the state for each DSP channel and the DSP. DSPRM maintains a resource table for each DSP. The following responsibilities belong to DSPRM:
- Discover the on-board DSP SIMM modules and, based on the user configuration, determine the type of application image that a DSP uses.
- Reset DSPs, bring up DSPs, and download application images to DSP.
- Maintain the DSP initialization states and the resource states and manage the DSP resources (allocation, deallocation, and error handling of all DSP channels for transcoding and conferencing).
- Interface with the backplane Protocol Control Information (PCI) driver for sending and receiving DSP control messages.
- Handle failure cases, such as DSP crashes and session terminations.
- Provide a keepalive mechanism between the DSPs and the primary and backup Cisco Unified Communications Managers. The primary Cisco Unified Communications Manager can use this keepalive to determine when DSPs are no longer available.
- Perform periodic DSP resource checks.
When a request is received from the signaling layers for a session, the system assigns the first available DSP from the respective pool (transcoding or conferencing), as determined by media resource groups and media resource group lists, along with the first available channel. DSPRM maintains a set of MAX limits (such as maximum conference sessions per DSP or maximum transcoding session per DSP) for each DSP.
A switchover occurs when a higher order Cisco Unified Communications Manager becomes inactive or when the communication link between the DSPs and the higher order Cisco Unified Communications Manager disconnects. A switchback occurs when the higher order Cisco Unified Communications Manager becomes active again and DSPs can switch back to the higher order Cisco Unified Communications Manager. During a switchover and switchback, the gateway preserves active calls. When the call ends, the gateway detects RTP inactivity, DSP resources release, and updates occur on the Cisco Unified Communications Manager.