DSP not registered in the Box-to-Box redundancy design

[Difan Zhao]

We have two 4331 routers with PVDM4-32 cards in them that we plan to use as CUBE router for our new data center. Right now I am testing and learning the setup.

We want to use the Box-to-Box redundancy configuration for the CUBE functionality. That part actually works great so far with the testing. However, which may or may not be relevant that, only the active CUBE's DSP can register to the CUCM, not the standby. The standby just shows 

# show sccp
...
Transcoding Oper State: ACTIVE_IN_PROGRESS - Cause Code: SOCKET_OPEN_FAILED

Here are my config

--- CUBE01 ---

sccp local Loopback0
sccp ccm 10.135.3.21 identifier 2 priority 2 version 7.0
sccp ccm 10.135.3.11 identifier 1 priority 1 version 7.0
sccp
!
sccp ccm group 1
 bind interface Loopback0
 associate ccm 1 priority 1
 associate ccm 2 priority 2
 associate profile 1 register VSP_YYC-DSP-01
 switchback method immediate
 audio dscp default

--- CUBE02 --- 

sccp local Loopback0
sccp ccm 10.135.3.21 identifier 1 priority 1 version 7.0
sccp ccm 10.135.3.11 identifier 2 priority 2 version 7.0
sccp
!
sccp ccm group 1
 bind interface Loopback0
 associate ccm 1 priority 1
 associate ccm 2 priority 2
 associate profile 1 register VSP_YYC-DSP-02
 switchback method immediate
 audio dscp default

So is this setup supported that both DSPs can still be registered on the CUCM and can be used at the same time, even though one being used as the standby CUBE?

Thanks,

Difan

[R0g22 · Accepted solution]

You cannot have SCCP Media Resources on a CUBE HA. This is not supported. This is true for Conference bridge, Transcoding, HW MTP, and SW MTP.
You can use LTI based Transcoding. Starting XE 3.15, LTI Xcoding based calls are preserved. The DSP's need to be of the same capacity and in the same slot/subslot on the Active/Standby box.
But LTI is local to CUBE. CUCM won't invoke this.

[M02@rt37]

Hi @Difan Zhao

This is the cisco doc illustrating what you really need to do.

https://www.google.fr/url?sa=t&source=web&rct=j&url=https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-cube-dsp.pdf&ved=2ahUKEwiQqcnBxe_bAhWQpFkKHX6mBmkQFjABegQIABAB&usg=AOvVaw11LcZY9eMsEB_ZFYFPFL1J

[Jaime Valencia]

The supported HA with DSPs when used with CUBE HA is explained here:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-cube-dsp.html

What you're seeing is the expected behavior, and thus it's not recommended to be used, as if those resources are involved in a call, the call will not be preserved when failover occurs, you would need a 3rd ISR to place those resources.

[Difan Zhao]

Thanks guys. I wanted to register on the CUCM because I want to be able to use the DSP in both routers together to support more concurrent calls. 

It looks like even with the LTI, I won't be able to do it, correct? The DSP resource in the standby router will always be idle?

Thanks

Difan

[R0g22]

Nope. The router that is ACTIVE in the HSRP/RG redundancy, the LTI resource for that will be used. Once the failover happens, the calls will be preserved and checkpointed to the other standby box which would now become active.

[Difan Zhao]

Thanks. In the dspfarm profile config, there is "universal" as an optional keyword for the profile. What does it do? Apparently I could have 16 sessions without it, but only 12 with it configured. Thanks

(config)#dspfarm profile 1 transcode ?
  universal  Profile type Transcoding
  <cr>

[R0g22]

Universal Xcoder allows LBR to LBR transcoding i.e both the legs can be non-G711. Without that keyword, you have a classic transcoder which will only work if either call leg is G711.