Phone Proxy and MOH Failure

Unanswered Question
Feb 24th, 2009

We have been testing out the ASA UC Proxy functionality. It was fairly straight forward to configure, and we have a working setup now with one exception - when placed on hold, the off site phone does not receive music on hold.

When the call is placed on hold, the CM starts pumping out udp packets containing the MOH and destined for the Media Termination Address configured on the ASA. These packets hit the firewall and are promptly dropped.

Feb 24 2009 14:03:41: %ASA-7-710005: UDP request discarded from prodcm-be/26760 to inside:67.155.4.204/23394

Feb 24 2009 14:03:41: %ASA-7-710005: UDP request discarded from prodcm-be/26760 to inside:67.155.4.204/23394

Feb 24 2009 14:03:41: %ASA-7-710005: UDP request discarded from prodcm-be/26760 to inside:67.155.4.204/23394

A look at the ASP information shows

TEST-UCPROXY-ASA# sh asp drop frame

Flow is denied by configured rule (acl-drop) 358

And a packet-tracer

Phase: 1

Type: CAPTURE

Subtype:

Result: ALLOW

Config:

Additional Information:

MAC Access list

Phase: 2

Type: ACCESS-LIST

Subtype:

Result: ALLOW

Config:

Implicit Rule

Additional Information:

MAC Access list

Phase: 3

Type: FLOW-LOOKUP

Subtype:

Result: ALLOW

Config:

Additional Information:

Found no matching flow, creating a new flow

Phase: 4

Type: ROUTE-LOOKUP

Subtype: input

Result: ALLOW

Config:

Additional Information:

in 67.155.4.204 255.255.255.255 identity

Phase: 5

Type: ACCESS-LIST

Subtype:

Result: DROP

Config:

Implicit Rule

Additional Information:

Result:

input-interface: inside

input-status: up

input-line-status: up

output-interface: NP Identity Ifc

output-status: up

output-line-status: up

Action: drop

Drop-reason: (acl-drop) Flow is denied by configured rule

Finally, taking a look at the phone-proxy session info during an active call:

UCPROXY-ASA# sh phone-proxy media-sessions

3 in use, 5 most used

Media-session: 67.155.4.204/23920 :: client ip 192.168.221.71/29412

Lcl SRTP conn 67.155.4.204/23920 to 71.194.132.108/58919 tx_pkts 221 rx_pkts 222

Media-session: 67.155.4.204/20442 :: client ip 71.194.132.108/58919

Lcl RTP conn 67.155.4.204/20442 to 192.168.221.71/29412 tx_pkts 222 rx_pkts 221

Media-session: 67.155.4.204/30620 :: client ip 71.194.132.108/58918

Lcl RTP conn 67.155.4.204/30620 to 192.168.221.71/22856 tx_pkts 592 rx_pkts 594

And again when the call is placed on hold:

UCPROXY-ASA# sh phone-proxy media-sessions

2 in use, 5 most used

Media-session: 67.155.4.204/18176 :: client ip 71.194.132.108/0

Lcl RTP conn 67.155.4.204/18176 to 0.0.0.0/0 tx_pkts 0 rx_pkts 0

Media-session: 67.155.4.204/30620 :: client ip 71.194.132.108/58918

Lcl RTP conn 67.155.4.204/30620 to 192.168.221.71/22856 tx_pkts 592 rx_pkts 594

In both cases, .221.71 is the office phone, .132.108 is the remote phone. When on hold, the office side goes all 0's.

I am guessing that the issue here is the ASA not accepting an unsolicited udp flow from the Call Manager, but was wondering if anyone else has run into this or if it indicates a configuration issue or... ?

ASA is on 8.0.4, CM is v6, phone is a 7960. CM is configured to send the MOH as unicast, not multicast.

Again, all other aspects of this solution are working as expected. It is only music on hold which fails.

Thanks

I have this problem too.
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Tommer Catlin Tue, 02/24/2009 - 13:58

I think this is a limitation of phone proxy and you will not be able to send this to the remote device. I was trying to find a document of support Phone features with PhoneProxy, but I cant seem to find it. I'll keep looking.

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