Configuring MTP Software Support

A Media Termination Point (MTP) software device is an essential component of large-scale deployments of Cisco Unified Communications Manager (CUCM). In these deployments, the software MTP bridges the media streams between two connections by allowing the CUCM to relay the calls that are routed through Session Initiation Protocol (SIP) or H.323 endpoints through Skinny Client Control Protocol (SCCP) commands. The SCCP commands allow the CUCM to establish MTP for call signaling.

From Cisco IOS XE 17.8.1, you can configure the support for software MTP on Cisco Catalyst 8000V devices. If you use voice functionalities with your Cisco Catalyst 8000V device, you can leverage software MTP to enable and use supplementary services, such as Call Park and Call Transfer routed through an H.323 endpoint or an H.323 gateway.

Benefits

Configuring software MTP in Cisco Catalyst 8000V allows you to:

  • Register a Cisco Catalyst 8000V instance with the Unified CM as a Trusted Relay Point.

  • Leverage the SWMTP support when one of the end points does not support DTMF signaling.

Prerequisites for Configuring Support for Software MTP

  • Configure codec and packetization in the inbound-call legs and the outbound-call legs.

SRTP-DTMF Interworking

From Cisco IOS XE 17.10.1a, Secure Real-time Transport Protocol (SRTP) Dual-Tone Multi-Frequency (DTMF) interworking is supported with Software MTP in pass through mode. SMTP supports DTMF Interworking for nonsecure calls, and this feature adds support for SRTP DTMF interworking for secure calls.

CUCM support for this feature is expected to be implemented in a later release.

Restrictions for SRTP-DTMF Interworking

  • The SRTP-DTMF Interworking feature supports only the codec-passthrough format.

  • The SRTP-DTMF Interworking feature does not support multiple concurrent Synchronised Sources (SSRCs) with the same destination IP and port.

  • The calls that support SRTP-DTMF Interworking may have a minor performance impact as compared to calls supported on nonsecure DTMF interworking.

Supported Platforms for SRTP-DTMF Interworking

From Cisco IOS XE 17.10.1a, the following platforms support SRTP DTMF interworking with SMTP:

  • Cisco 4461 Integrated Services Router (ISR)

  • Cisco Catalyst 8200 Edge Series Platforms

  • Cisco Catalyst 8300 Edge Series Platforms

  • Cisco Catalyst 8000V Edge Software

Configuring Support for Software MTP

To enable and configure support for software MTP, perform the following steps.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. sccp local interface-type interface-number [port port-number ]
  4. sccp ccm {ipv4-address | ipv6-address | dns } identifier identifier-number [port port-number ] version version-number
  5. sccp
  6. sccp ccm group group-number
  7. associate ccm identifier-number priority number
  8. associate profile profile-identifier register device-name
  9. dspfarm profile profile-identifier {conference | mtp | transcode } [security ]
  10. trustpoint trustpoint-label
  11. codec codec
  12. maximum sessions {hardware | software } number
  13. associate application sccp
  14. no shutdown

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables the privileged EXEC mode. Enter your password, if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters the global configuration mode.

Step 3

sccp local interface-type interface-number [port port-number ]

Example:


Router(config)# sccp local gigabitethernet0/0/0

Selects the local interface that SCCP applications (transcoding and conferencing) use to register with the Cisco UCM.

  • interface type : The interface address or a virtual-interface address such as Ethernet.

  • interface number : The interface number that the SCCP application uses to register with the Unified CM.

  • (Optional) port port-number : The port number used by the selected interface. The applicable range is 1025 to 65535, and the default is 2000.

Step 4

sccp ccm {ipv4-address | ipv6-address | dns } identifier identifier-number [port port-number ] version version-number

Example:


Router(config)# sccp ccm 10.1.1.1 identifier 1 version 7.0+

Adds a Unified CM server to the list of available servers and sets the following parameters:

  • ipv4-address : The IP version 4 address of the Cisco UCM server.

  • ipv6-address : The IP version 6 address of the Cisco UCM server.

  • dns : The DNS name.

  • identifier : The number that identifies the Unified CM server. The applicable range is 1 to 65535.

  • port port-number (Optional): The TCP port number. The applicable range is 1025 to 65535, and the default is 2000.

  • version version-number : The Unified CM version. The valid versions are 3.0, 3.1, 3.2, 3.3, 4.0, 4.1, 5.0.1, 6.0, and 7.0+.

Step 5

sccp

Example:


Router(config)# sccp

Enables the SCCP and its related applications (transcoding and conferencing).

Step 6

sccp ccm group group-number

Example:


Router(config)# sccp ccm group 10
Creates a Unified CM group and enters the SCCP Unified CM configuration mode.

  • group-number : Identifies the Cisco Unified CM group. The applicable range is 1 to 50.

Step 7

associate ccm identifier-number priority number

Example:


Router(config-sccp-ccm)# associate ccm 10 priority 3

Associates a Unified CM with a group and establishes its priority within the group.

  • identifier-number : The Unified CM identifier. The applicable range is 1 to 65535.

  • priority number : The priority of the Unified CM within the Unified CM group. The applicable range is 1 to 4. The highest priority is 1.

Step 8

associate profile profile-identifier register device-name

Example:


Router(config-sccp-ccm)# associate profile 1 register MTP0011

Associates a Digital Signal Processor (DSP) farm profile with a Unified CM group.

  • profile-identifier : The DSP farm profile. The applicable range is 1 to 65535.

  • register device-name : The device name in Unified CM. A maximum of 15 characters can be entered for the device name.

Step 9

dspfarm profile profile-identifier {conference | mtp | transcode } [security ]

Example:


Router(config-sccp-ccm)# dspfarm profile 1 mtp

Enters the DSP farm profile configuration mode and defines a profile for the DSP farm services.

  • profile-identifier : The number that uniquely identifies a profile. The applicable range is 1 to 65535, and there is no default.

  • conference : Enables a profile for conferencing.

  • mtp : Enables a profile for MTP.

  • transcode : Enables a profile for transcoding.

  • security (Optional): Enables a profile for secure DSP farm services. For more information on configuration examples, see section Sample Software MTP Support Configuration.

Step 10

trustpoint trustpoint-label

Example:

Router(config-dspfarm-profile)# trustpoint dspfarm

(Optional) Associates a trustpoint with a DSP farm profile.

Step 11

codec codec

Example:

Router(config-dspfarm-profile)# codec g711ulaw

Specifies the codecs supported by a DSP farm profile.

  • codec-type: Specifies the preferred codec. Enter ? for a list of supported codecs.

    Repeat this step for each supported codec.

Step 12

maximum sessions {hardware | software } number

Example:


Router(config-dspfarm-profile)# maximum sessions software 10

Specifies the maximum number of sessions supported by the profile.

  • hardware : The number of sessions that the MTP hardware resources support.

  • software : The number of sessions that the MTP software resources support.

  • number : The number of sessions that are supported by the profile. The applicable range is 0 to x, and the default is 0. The value of x is determined at runtime depending on the number of resources available with the resource provider.

Step 13

associate application sccp

Example:


Router(config-dspfarm-profile)# associate application sccp

Associates SCCP to the DSP farm profile.

Step 14

no shutdown

Example:


Router(config-dspfarm-profile)# no shutdown

Changes the status of the interface to the UP state.

Sample Software MTP Support Configuration

The following output is a sample of the software MTP support configuration in a Cisco Catalyst 8000V device: 

sccp local GigabitEthernet1
sccp ccm 9.35.46.100 identifier 1 priority 1 version 7.0 
!
sccp ccm group 1
 bind interface GigabitEthernet1
 associate ccm 1 priority 1
 associate profile 10 register SWMTP1
 associate profile 1 register c8kvsmall-mtp1
 associate profile 2 register c8kv-sec-swmtp1
!
!
!
dspfarm profile 1 mtp  
 codec g711ulaw
 maximum sessions software 20000
 associate application SCCP

The following example shows a sample configuration for the SRTP-DTMF Interworking feature-with secure dspfarm profile:

sccp local GigabitEthernet0/0/0
sccp ccm 172.18.151.125 identifier 1 version 7.0
sccp
!
sccp ccm group 1
 bind interface GigabitEthernet0/0/0
 associate ccm 1 priority 1
 associate profile 1 register Router
!
dspfarm profile 1 mtp security
 trustpoint IOSCA
 codec g711ulaw
 codec pass-through
 tls-version v1.2
 maximum sessions software 5000
 associate application SCCP

Note

SR-TP traffic can pass through an SMTP resource when the dspfarm profile is provisioned with codec pass-through, and if it does not have TLS and security-related configuration. For traffic flows that require SRTP-DTMF interworking support, the SMTP dspfarm profile must include the security keyword and the TLS and codec pass-through configuration. This dspfarm resource profile can also pass through SRTP traffic independent of SRTP-DTMF interworking support.

Verifying Software MTP Support

To verify whether you have successfully configured the support for SWMTP in your Cisco Catalyst 8000V device, run the show sccp command: 

Router# show sccp
 
SCCP Admin State: UP
Gateway IP Address: 10.13.40.157, Port Number: 2000
IP Precedence: 5
User Masked Codec list: None
Call Manager: 10.13.40.148, Port Number: 2000
                Priority: N/A, Version: 6.0, Identifier: 1
                Trustpoint: N/A

To verify the dspfarm profile, run the show dspfarm profile command: 

Router# show dspfarm profile 1
Dspfarm Profile Configuration

 Profile ID = 1, Service = MTP, Resource ID = 1   
 Profile Service Mode : Non Secure 
 Profile Admin State : UP 
 Profile Operation State : RESOURCE ALLOCATED 
 Application : SCCP   Status : NOT ASSOCIATED 
 Resource Provider : NONE   Status : NONE 
 Total Number of Resources Configured : 20000 
 Total Number of Resources Available : 20000 
 Total Number of Resources Out of Service : 0 
 Total Number of Resources Active : 0
 Hardware Configured Resources : 0 
 Hardware Resources Out of Service: 0 
 Software Configured Resources : 20000 
 
 Number of Hardware Resources Active : 0 
 Number of Software Resources Active : 0
 Codec Configuration: num_of_codecs:1 
 Codec : g711ulaw, Maximum Packetization Period : 30

To verify information about the secure dspfarm profile status, use the show dspfarm profile command and check that the secure service mode is set: 

Router# show dspfarm profile 2
Dspfarm Profile Configuration
 Profile ID = 2, Service = MTP, Resource ID = 2
 Profile Service Mode : secure
 Trustpoint : IOSCA
 TLS Version  : v1.2
 TLS Cipher   : AES128-SHA
 Profile Admin State : UP
 Profile Operation State : ACTIVE
 Application : SCCP   Status : ASSOCIATED
 Resource Provider : NONE   Status : NONE
 Total Number of Resources Configured : 8000
 Total Number of Resources Available : 8000
 Total Number of Resources Out of Service : 0
 Total Number of Resources Active : 0
 Hardware Configured Resources : 0
 Hardware Resources Out of Service: 0
 Software Configured Resources : 8000
 Number of Hardware Resources Active : 0
 Number of Software Resources Active : 0
 Codec Configuration: num_of_codecs:2
 Codec : pass-through, Maximum Packetization Period : 0
 Codec : g711ulaw, Maximum Packetization Period : 30

To verify the call connection between the endpoints, run the show sccp connection details command. This command shows that the connection is successfully established. This is indicated through the active connections and call legs at the end of the configuration output: 

Router# show sccp connection details

bridge-info(bid, cid) - Normal bridge information(Bridge id, Calleg id)

mmbridge-info(bid, cid) - Mixed mode bridge information(Bridge id, Calleg id)

sess_id    conn_id    call-id   codec  pkt-period  dtmf_method     type    bridge-info   mmbridge-info  srtp_cryptosuite  dscp
call_ref   spid       conn_id_tx                                           (bid, cid)    (bid, cid)
16782237   16777254   110       g711u  20          rfc2833_pthru   rtpspi  (40,0)         N/A            N/A               184
29751839   16777216   -
16782237   16777253   109       g711u  20          rfc2833_report  rtpspi  (40,0)         N/A            N/A               184
29751839   16777216   -
Total number of active session(s) 1, connection(s) 2, and callegs 2

For SMTP secure DTMF, the show sccp connections command displays the codec type (pass-th), the s-type (s-mtp), and information about the DTMF method (rfc2833_pthru): 

Router#sh sccp connections

sess_id    conn_id    stype   mode      codec    sport  rport   ripaddr conn_id_tx   dtmf_method

16791234   16777308   s-mtp   sendrecv  pass_th  8006   24610   172.18.153.37        rfc2833_pthru
16791234   16777306   s-mtp   sendrecv  pass_th  8004   17576   172.18.154.2         rfc2833_report

Total number of active session(s) 1, and connection(s) 2

To display information about RTP connections, use the show rtpspi call command: 


Router# show rtpspi call 
RTP Service Provider info:
No. CallId  dstCallId   Mode      LocalRTP  RmtRTP  LocalIP     RemoteIP    SRTP 
1    22      19         Snd-Rcv   7242      17510   0x90D080F   0x90D0814    0   
2    19      22         Snd-Rcv   18050     6900    0x90D080F   0x90D080F    0

If SRTP DTMF interworking is active, the SRTP field shows a non-zero value:

Router# show rtpspi call
RTP Service Provider info:
No. CallId  dstCallId   Mode      LocalRTP  RmtRTP  LocalIP     RemoteIP    SRTP
1   13      14          Snd-Rcv   8024      18270   0xA7A5355   0xAC129A02   1
2   14      13          Snd-Rcv   8026      24768   0xA7A5355   0xAC129925   1