Intermittent One-way Audio over NEM VPN

[Sam Byers]

I have a user that uses an ASA 5505 in NEM to have his/her laptop and Cisco IP Phone at home. The ASA 5505 establishes a tunnel to an ASA 5510, which is connected and speaking EIGRP to our core switch. Off of the core switch we have our CCM cluster.

The issue happens on the first call after a long period of no calls. After if happens on the first call, he/she can continue to make calls without the issue. I though it was a timeout issue, but his/her ASA configuration is the exact same. Also, he/she is using the same group policy, tunnel-group etc. as everyone else with the same setup.

When the issue happens, he/she can't hear the other party, but they can hear her/him.

This issue happens regardless if she has a PC behind the phone or not.

Internal calls and external are both affected.

I am aware that most one-audio issues are RTP connectivity issues between the two endpoints. I can clearly see in the routing table of all of our routers, that the route to the subnet her phone is on has not changed for days, and she has had the issue within that amount of time.

I'm looking for a good place to start troubleshooting that doesn't require me to to a pcap. If all else fails, I will do a pcap, but I'm trying to be some what judicious with my time.

I am definitely able to accept it may be his/her router at home since it's one of the only unique things about his/her setup, compared to the other 20 people I have doing this.

Thanks in advance.

Cisco IP Phone 7941

CCM 7.1.5.32900-2

ASA 5505 8.2(5)

ASA 5510 8.2(5)

Edit: Moved to VPN

[Gaurav Purohit · Accepted solution]

Hello,

I'd suggest by asking if the packet count increases during the active call. (press '?' twice). 

I also believe you have asked this question under wrong discussion group, it must be under security thread instead of voice.

[Sam Byers]

This was a split tunneling issue.

The number of networks I had in the split tunnel was over 50, and it caused issues with VoIP.

I have seen problems when making EzVpn (NEM) connections with IOS and a split tunnel that has more than 50 networks. The log will print out that it doesn't like more than 50 networks.

The log in the ASA 5505 did not complain about it. Also, I have many ASA 5505's with the same split tunnel that never have an issue.

So, if anyone has this issue, here it is.