A DSPFarm on a router is a pool of DSP resources configured for particular functions (services);
- Conference Bridge
This DSPFarm needs to register itself (the DSPFarm and resource types) with a call control element. This call control element can be either CUCM or CME. This is done by using the SCCP group configuration and SCCP protocol on the router to register with call control elements, more than one group can be created to register different pools (DSPFarm) resources with many simultaneous call control elements.
The common configuration is for a single group (called ‘ccm group’ in IOS) with an ordered (preference) list of call control elements to register with. All resources in the ccm group are registered with the most preferred call control element. If this call contol element is not available or fails, the next in the ordered list (next preference) is used to register the resources.
So in the case of a router than had DSPFarm resources that registers these with CUCM, where the connection to CUCM fails and if the router is running SRST, the next available call control element (if configured in the list) can be the local router running SRST. The DSPFarm resources then register with this local SRST instance (telephony-service) and therefore provides DSPFarm resources to the SRST service when active. When CUCM is back online, the DSPFarm will de-register with the local telephony-service and register with a more preferred call control element (CUCM).
As the DSPFarm registers with a call control element, it can register locally with SRST, CME and also with non local call control elements such as CUCM and also CME on separate routers therefore meaning a few routers could provide DSPFarm resources to a distributed network of CME routers therefore reducing the overall requirement for DSPs on those distributed routers. Some DSP resources may still be required locally on the distributed routers for PSTN connections (FXO, E1, etc).
Note that the call control element that the DSPFarm registers with must be configured to accept the registration. CUCM has Media Resource configuration and IOS has the telephony-service configuration as the example shows below.
! telephony-service sdspfarm units 2 sdspfarm transcode sessions 4 sdspfarm tag 1 mtpa0ecf9440b88 sdspfarm tag 2 CFB_BR3_GW conference hardware !
The following example shows the DSPFarm configuration for registering to one call control element at 192.168.5.1, more can be added with ‘sccp ccm’ and ‘assocaiate ccm x priority y’ paying attention to the unique call control element identifiers and priorities.
! voice-card 0 dsp services dspfarm ! sccp local GigabitEthernet0/0.500 ! sccp ccm 192.168.5.1 identifier 1 version 7.0 ! sccp ! sccp ccm group 1 bind interface GigabitEthernet0/0.500 associate ccm 1 priority 1 associate profile 1 register mtpa0ecf9440b88 associate profile 2 register CFB_BR3_GW keepalive retries 5 ! ! ! dspfarm profile 1 transcode codec g729abr8 codec g729ar8 codec g711alaw codec g711ulaw codec g729r8 maximum sessions 4 associate application SCCP ! dspfarm profile 2 conference codec g711ulaw maximum sessions 1 associate application SCCP !