Table Of Contents
PBX Interoperability Guidelines
for the 7x00 Series Routers
March 6, 2002
This document illustrates differences in configuring voice features on digital T1 interfaces or E1 interfaces on platforms using the High Density Voice Network Module (including Cisco 2600 and Cisco 3600 series routers), and those using Digital Voice Port Adapters (including Cisco 72xx, 7200VXR, and 75xx series routers). For interoperability with specific outside vendors, refer to the following URLs:
•Fujitsu 9600 ES
•Lucent Definity G3R
•NEC NEAX 2400
•Nortel Option 11C
•Siemens Hicom 300 Series
•Toshiba Strada DK424
All of the platforms mentioned share the same core set of high-level Cisco IOS voice and hardware features, since they use the same DSP (T1549) hardware and firmware. Thus, no differences exist in configuring the following features:
•T1 or E1 controller configurations, such as line code, framing, clock, FDL,and cable length loopback
•T1 or E1 signalling protocols, such as T1 CAS, FXS FXO, E&M, E1 R2, ISDN PRI and QSIG configurations using ds0-group or pri-group in controller mode
•Voice-port related features like connection-trunk, comfort noise, echo cancellation, input gain, output attenuation, and signaling conditioning
•TDM Drop and Insert
•Dial-peer features such as codec selection, playout buffer, translation rules, fax, and DTMF relay
•Common Voice over Packet features such as H.323, RTP, FRF.11 and FRF.12, GW/GK interaction
•High-level applications like PBX trunking using Transparent-CCS, or hub and spoke VoFR applications
Some differences in configuring some features might occur. For example, support for newer software features, including, but not limited to, Advanced Voice Busyout, or Remote Telephony Survivability System, T.38 fax, or Interactive Voice Response, can be integrated into different Cisco IOS releases, since each platform has its own roadmap for the release of specific advanced features.
Some configuration commands, such as the ones used to configure low-level interface features, could also be different.
The following section will address these differences, using an example from a different platform, for replacing or upgrading a voice gateway.
T1 or E1 Selection
Because both PA-VX and PA-MCX are software configurable for T1 or E1 mode, a special command must be used to specify which standard is used. This is a global configuration mode command of the form:
PA-VX and PA-MCX:card type [T1|E1] <slot no>
Controller type is not configurable
Chassis Clock Reference
Both the Cisco 7200VXR and the Cisco 3660 equipped with an MIX module, support an internal TDM bus which features multi-level clock source prioritization. An MIX-enabled T1 interface or E1 interface can be selected to provide clock resources for the entire chassis, or you can use the default of the internal PLL oscillator.
Cisco 7200VXR: Use a single global configuration commandframe-clock-select [T1 | E1] <slot> <priority>
Cisco 3660 with MIX module: Use the following two commands:network-clock-participate nm <slot>network-clock-select <priority> [T1 | E1] <slot/port>
Configuring an external clock source is not mandatory. However, when the circuits or devices connected to the Cisco 7200VXR drive their own clock and the router chassis uses the internal PLL, the T1 or E1 controller experience slips, indicating a clock discrepancy. A small number of slips will not affect voice quality, but they can severely impact the fax. Therefore, it is recommended that this command always be configured to have the T1 or E1 controller error-free.
Codec Complexity and DSPfarm
To configure the "codec algorithm complexity," which affects the number of voice channels that a single DSP can process, PA-VXC and NM-HDV use different configuration modes:
PA-VX:interface dspint dsifarm <slot/port>codec domplexity [medium | high]
NM-HDV:voice-card <slot>codec complexity [medium | high]
These commands will automatically appear in the configuration and do not require explicit configuration unless required by the application. The platforms which support DSP farming will also be configured with the modes described above. the PA-VX also supports reset and shutdown of individual DSP in this manner.
The PA-VX does not support data connections (channel-group), but they are supported on both the PA-MCX and NM-HDV. To configure a PA-MCX for pure data service, use the options "data" as shown below. To configure a PA-MCX for mixed data/voice application, chose either the "cas-voice" or "ccs-voice", depending on the actual signaling protocol used on the line.
PA-MCX:controller [T1|E1] <slot/port>service-type [cas-voice | ccs-voice | data]
Does not need an explicit configuration for mixed voice/data applications