Hi Alistair,
Cisco Unified Communications Manager assigns conference resources to calls on a dynamic basis. The available conference resource and the enabled codec provide the maximum number of concurrent, secure conferences allowed per router. Because transmit and receive streams are individually keyed for each participating endpoint (so no rekeying is necessary when a participant leaves the conference), the total secure conference capacity for a DSP module equals one-half the nonsecure capacity that you can configure.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/security/6_0_1/secugd/secuconf.html#wp1090249
Table 5 DSP Theoretical Session Capacities
Application | NM-HD-1V/2V
(1 DSP) | NM-HD-2VE
(3 DSPs) | NM-HDV2
(16 DSPs) | 2801/2811
(2 PVDM2-64) | 2821/2851
(3 PVDM2-64) | 3825, 3845
(4 PVDM2-64) |
|---|
Conferencing |
G.711 | 8 sessions
(64 conferees) | 24 sessions
(192 conferees) | 50 sessions
(400 conferees) | 50 sessions
(400 conferees) | 50 sessions
(400 conferees) | 50 sessions
(400 conferees) |
G.729 | 2 sessions
(16 conferees) | 6 sessions
(48 conferees) | 32 sessions
(256 conferees) | 16 sessions
(128 conferees) | 24 sessions
(192 conferees) | 32 sessions
(256 conferees) |
Transcoding |
G.711 a-law/u-law <-> G.729a/G.729ab/ | 8 sessions | 24 sessions | 128 sessions | 64 sessions | 96 sessions | 128 sessions |
G.711 a-law/u-law <-> G.729/G.729b/ | 6 sessions | 18 sessions | 96 sessions | 48 sessions | 72 sessions | 96 sessions |
Voice Termination |
G.711 a-law/u-law | 16 sessions | 48 sessions | 256 sessions | 128 sessions | 192 sessions | 256 sessions |
G.726, G.729a, G.729ab | 8 sessions | 24 sessions | 128 sessions | 64 sessions | 96 sessions | 128 sessions |
G.729, G.729b, G.723.1, G.728 | 6 sessions | 18 sessions | 96 sessions | 48 sessions | 72 sessions | 96 sessions |
Table 6 Theoretical System Capacities for One DSP
Application | G.711 a-law/u-law | G729 a/ab | G.729, G.729b |
|---|
Conferencing | 8 sessions
(8 x 8 = 64 conferees) | 2 sessions
(8 x 2 = 16 conferees) | 2 sessions
(8 x 2 = 16 conferees) |
Conferencing on PVDM2-8 | 4 sessions
(4 x 8 = 32 conferees) | 1 session
(1 x 8 = 8 conferees) | 1 session
(1 x 8 = 8 conferees) |
Hardware MTP | 16 sessions | — | — |
Transcoding | 8 sessions | 8 sessions | 6 sessions |
http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/interop/intcnf2.html#wp1068869
Cheers!
Rob
