Cisco Unified Border Element

CUBE 9.0 Local Transcoding Interface (LTI)

Document ID: 115018

Updated: Nov 28, 2012

Contributed by Hussain Ali, Cisco TAC Engineer.



The Local Transcoding Interface (LTI) was a Cisco Unified Border Element (CUBE) transcoding feature originally introduced on Aggregation Services Routers (ASR) platform in 15.1(1)S. Starting with CUBE 9.0, this feature was added to ISR G2 platforms with additional enhancements. LTI includes an internal API to access digital signal processor (DSP) resources. This API bypasses the need for CME configuration and licensing, as well as the use of Skinny Client Control Protocol (SCCP). When both LTI-based and SCCP-based transcoding are configured, LTI takes precedence.



Cisco recommends that you have knowledge of these topics:

  • CUBE

  • Local Transcoding Interface (LTI)

  • SCCP

Components Used

The information in this document is based on Cisco Unified Border Element (CUBE) 9.0.

Comparison with SCCP-based Transcoding

CME/SCCP based XcodingLTI based Xcoding
SCCP protocol is used for controlling DSP resources used for transcoding.

Internal API are used to access DSP resources for transcoding.

Transcoding resources (DSPFARM) and CUBE can be on different platforms.

Transcoding resources (DSPFARM) and CUBE need to be on the same platform.

SCCP client (SCCP CCM...) configuration and SCCP server (telephony service) configuration is required for CUBE-Ent configuration apart from DSPFARM profile configuration.

Only DSPFARM profile configuration is required. SCCP configuration  and CUCME configuration is not required when used with CUBE-Ent.

DSPFARM registers with CUCME over TCP socket, using SCCP.

No TCP socket is opened and no registration is used.

DSPFARM profile is associated to SCCP using CLI.

dspfarm profile <tag> transcode
associate application sccp

SSPFARM profile is associated to a new application type CUBE.

dspfarm profile <tag> transcode
associate application cube
High density transcoding needs to be enabled through the CLI for higher performance. High density transcoding will be flow around through the transcoderInherently high density and always flow through. Matches performance of high density transcoding. All flow through features are supported on transcoding calls.
SRTP-RTP using transcoder requires crypto pki trustpoint configuration to establish the TLS connection with SCCP server.

Crypto PKI trustpoint configuration is not required for SRTP-RTP calls.

Sample Audio Transcoding Configuration

!--- Enable CUBE
voice service voip
allow-connections sip to sip
allow-connections h323 to h323
allow-connections h323 to sip
allow-connections sip to h323

!--- Dspfarm profile configuration with associate
!--- application CUBE for LTI transcoding.
dspfarm profile 1 transcode universal
codec g729ar8
codec g729br8
codec g711alaw
codec g711ulaw
codec g729r8
maximum sessions 12
associate application CUBE

!--- Only dspfarm profile configurations are needed for
!--- LTI-based transcoding. All the SCCP-based transcoding
!--- features will be supported with LTI-based transcoding.


Verify Registration

CUBE#show dspfarm profile 1
Dspfarm Profile Configuration
Profile ID = 1, Service =Universal TRANSCODING, Resource ID = 1
Profile Description :
Profile Service Mode : Non Secure
Profile Admin State : UP
Profile Operation State : ACTIVE << Profile 1 is ACTIVE
Application : CUBE Status : ASSOCIATED << Profile 1 (LTI) is associated with CUBE application
Resource Provider : FLEX_DSPRM Status : UP
Number of Resource Configured : 12
Number of Resources Out of Service : 0
Number of Resources Active : 0
Codec Configuration: num_of_codecs:5
Codec : g729ar8, Maximum Packetization Period : 60
Codec : g729br8, Maximum Packetization Period : 60
Codec : g711alaw, Maximum Packetization Period : 30
Codec : g711ulaw, Maximum Packetization Period : 30
Codec : g729r8, Maximum Packetization Period : 60
Updated: Nov 28, 2012
Document ID: 115018