Audio Transcode and Video Relay
The SBC SWe Cloud inter-operates with a third-party transcoding platform called Media Resource Function (MRF) to transcode audio and relay video/T140.
Note
Only SBC SWe on OpenStack (D-SBC) supports this enhancement.
The SBC supports the following:
- Relaying both audio and video streams.
- Relaying audio, video and T140 streams.
- Audio transcode through MRF and video relay.
- Audio transcode through MRF and video/T140 relay.
- Audio transcode through MRF and T140 relay.
Note
The SBC SWe supports this functionality only for MRF-transcoded calls on D-SBC platforms.
Note
If the Packet Service Profile is configured as "transcode-only", the SBC transcodes the audio and relays video/ T140.
SBC SWe Cloud Limitations
- The SBC SWe does not support audio-less call.
- The SBC SWe does not support video licenses. Only one video stream is supported.
- The SBC SWe supports only video and T140 streams among the non-audio streams.
For more information on CLI changes and CDR changes, refer to:
Prerequisites to Invoking MRF
Note
The first three activities below cause the SBC to include DSP when invoking MRF.
- Configure MRF Profile in S-SBC
- Invoking MRF as Transcoder for D-SBC
- Enable transcoding at the Packet Service Profile (refer to ).
- Create a Path Check Profile, ARS profile, and CAC profile during the initial configuration
Note
Ribbon recommends to not configure Path Check Profile and SIP ARS Profile on the same peer to avoid unexpected results. As a general rule, the Path Check Profile is configured on the access leg where there is less traffic, and the ARS Profile is configured on the peer leg where there is continuous traffic.
Configure MRF Profile in S-SBC
This configuration example explains how to configure the MRF cluster profile in the S-SBC. The MRF servers are configured as FQDN or IP Address is decided by Routing Type configured in the MRF Profile.
Configure Private LIF Groups in M-SBC
This configuration example explains the CLI command required to configure the MRF cluster profile in M-SBC.
Create a Path Check Profile, ARS profile, and CAC Profile During Initial Configuration
Path Check Profile
The Path Check Profile specifies the conditions that constitute a connectivity failure, and in the event of such a failure, the conditions that constitute a connectivity recovery.
- For more information on path check, refer Service Profiles - Path Check Profile
For more information on creating IP Peer, refer to System Provisioning - Ip Peer for GUI or Zone - IP Peer - CLI.
NoteIf using an IP address, create different IP Peers for each IP addresses configured in MRF cluster profile as MRF IP address and attach the Path Check Profile.
If using an FQDN, create the IP Peer with FQDN and attach the Path Check Profile.
ARS Profile
The Address Reachability Service (ARS) determines whether a server is reachable, able to blacklist a server IP address when unreachable, and remove the server from blacklist state. ARS profiles can be created to configure blacklisting and recovery algorithm variants. For more information, refer to Service Profiles - Sip Ars Profile (EMA) or SIP ARS Profile - CLI.
Create an ARS profile and attach to the MRF TG as configured in the cluster profile. The ARS feature controls the congestion to handle the 503 response.
CAC Profile
The Call Admission Control (CAC) feaure creates and configures a profile that provides each registered SIP or static endpoint to have individual limits on the number of active calls and the call rates. For more information, refer to CAC Provisioning - SIP CAC Profile.
- For End point CAC, create CAC profile and attach to the IP Peer.
For TG CAC, create CAC profile and attach to the MRF TG as configured in the cluster profile.
NoteEnd point CAC does not support FQDN.
NoteBandwidth CAC is not supported for both TG and Peer level.
Invoking MRF Server
In a cluster profile, you can configure the routing type for FQDN or a list of IP addresses. If FQDN is chosen, the FQDN resolves into a list of IP addresses.
If the MRF profile is configured with a list of MRF server IP addresses and a call is routed to MRF server(s) as follows:
- S-SBC tries to connect to the configured MRF server IP addresses in a round-robin fashion.
- If any failure/no response is received from an MRF server for a specific IP address, the same IP address is blacklisted. When blacklisted, S-SBC continuously sends an option message to MRF server to check whether the IP is active/inactive. Once the IP is active, S-SBC removes the IP address from the blacklist state and tries to connect to the same IP when the next call is routed to MRF Server.
- S-SBC tries for the next available MRF server IP address configured in the list alternatively.
- This process is repeated until S-SBC either receives a SUCCESS response from any of the MRF servers or all the MRF server IP addresses in list is exhausted.
Example: The MRF profile is configured with a list of MRF server IP addresses such as IP1, IP2, IP3 and IP4, then for the 1st call, S-SBC tries to connect for MRF server IP1. Meanwhile, S-SBC received 2nd, 3rd, 4th calls and connected to the MRF servers IP2, IP3 and IP4 respectively. For the 1st call, the S-SBC has received a Failure/No response from the MRF server IP1. Hence, the S-SBC tries with IP2 and connects successfully.
Signaling and Media Flow
Signaling and Media flow for a transcoded call using S-SBC, M-SBC and MRF:
- S-SBC: Provides signaling services and responsible for allocating/activating/managing various resources (including MRF). Configures media flow through M-SBC and MRF.
- M-SBC: Provides media services. Public interface is used to communicate with peers and private interface is used to communicate with MRF.
- MRF: Provides transcoding services. Configured in private network of SBC and uses RFC-4117 interface to communicate with S-SBC.
Signaling and Media Flow
Overview
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