delay dtone intermittent

[trilogy8]

For an LSP that is registered to the core, does the dialtone come from the core? Getting some reports of delayed dtone for periods of time and inability for admins to grab professional calls off bridges. Issue then resolves itself. Is this a network related issue?

 

[ZeroZeroOne]

What is the hardware setup? Core servers in a main office with LSP and media-gateway in a remote office? Software version? Type of phones?
It could be network related, but it's hard to tell. It could be a mismatch on Ethernet ports, such as the local media-gateway is set for 100/full but the switch is set for Auto. That used to be a common issue but if the delay in dial tone is only recent or only during peak usage then this is probably not the problem.

Phones will register to the Core Processor Ethernet (PROCR) but use DSP resources from media-gateways. If the local media-gateway is overwhelmed then DSP resources in other offices will be used, depending on how your ip-network-regions are configured. If you have 80 local VoIP channels and 100 users making tons of calls then it is possible that some users have to wait for a free channel on the local gateway or are experiencing a delay getting resources from another office.

That's just a really brief overview. You can check the DSP usage by connecting to the gateway and running show voip-parameters to see the usage of your VoIP channels.

g430-001(super)# show voip-para

VOIP ENGINE PARAMETERS
---------------------------------------------------------
Fault Status        : No Fault Messages
Additional Status   : No Status Messages

CURRENT STATE
---------------------------------------------------------
In Use     : 0 of 120 channels, 0 of 3600 points (0.0% used)

VoIP-DSPs PARAMETERS
-----------------------------------------------------------
VoIP Child Type  SUFFIX HW      FW      Chan    Admin   Oper    Fault
Slot Board              VINTAGE VINTAGE InUse   State   State   Status
---- ----- ----- ------ ------- ------- ------- ------- ------- ---------
1    -- Not Installed --
2    VOIP  MP120 A      0       144       0/120 Release Idle    No Error

Done!
g430-001(super)#

Capturing information at the exact moment it happens can be tricky. list trace station xxxx is helpful but only if that station is having problems exactly when you are watching.

 

[trilogy8]

That's odd. it's a remote office g450MG/s8300 6.3.x LSP hung off a core CM in another location. It only has about 35 h.323 phones, with 80 voip resources. Unless VoIP resources are getting hung somehow I don't see how oversubscribing is possible.

 

[ZeroZeroOne]

OK, so we know DSP resources aren't the issue in that office.
Here are some other questions that may help point you in the right direction.

Is the problem just recent or have users always had this issue?
Does the problem seem to only happen at specific times of the day or can it be any time?
What is the connection back to the core? MPLS? Internet?
Are phones registered to the correct ip-network-region?
Is the network set up with a unique voice VLAN with priority over regular data?

I wish there was a feature setting "turn off dial tone delay" we could just set but I'm afraid it won't be that easy. Try tracing a user that often has the problem to see if you can capture the moment.

 

[trilogy8]

Our network team is using a SD WAN appliance and they're going to map out all the flows to ensure all the voice signaling and media is only allowed over MPLS. There's a possibility this policy is misconfig'd and at some condition, some of the voice traffic was sent over Internet VPN. This issue has only happened twice.. once last week and this week.