Wireless Access

Hi all.

We have deployed voice over wireless with Cisco 7921 and 7925 IP Phones and an Aruba6000 controller (ArubaOS 6.4.x) with a mix os AP 105, 124 and 215 and a SSID dedicated only for voice. Lately some users complained of the calls finishing just after picking up the phone or after only a few seconds and in the Dashboard of the controller (Dashboard > UCC > QoS Details, for example) we are noting that many calls terminate after only a few seconds (in some cases after 1 second) with reason "TCLAS flow deleted".

I've been unable to found some Aruba document refering to such term, although it seems clear that it's related with QoS/TSPEC. The voice VAP has an WMM Traffic management profile applied, and a VoIP Call Admission Control profile applied to the groups that contain such VAP (the SSID profile has an High-throughput SSID Profile, by the way). The profiles are configured accordingly, as far as possible, the guidelines of Cisco for the 792x phones (http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/cuipph/7925g/7_0/english/deployment/guide/7925dply.pdf). Here are the profiles:

SSID Profile
---------------------
Parameter Value
--------- -----
SSID enable Enabled
ESSID XXXXX
Encryption wpa2-psk-aes
Enable Management Frame Protection Disabled
Require Management Frame Protection Disabled
DTIM Interval 2 beacon periods
802.11a Basic Rates 12 24
802.11a Transmit Rates 12 18 24
802.11g Basic Rates 12 18 24
802.11g Transmit Rates 12 18 24
Station Ageout Time 1000 sec
Max Transmit Attempts 3
RTS Threshold 2333 bytes
Short Preamble Enabled
Max Associations 64
Wireless Multimedia (WMM) Enabled
Wireless Multimedia U-APSD (WMM-UAPSD) Powersave Enabled
WMM TSPEC Min Inactivity Interval 0 msec
Override DSCP mappings for WMM clients Disabled
DSCP mapping for WMM voice AC 56
DSCP mapping for WMM video AC 40
DSCP mapping for WMM best-effort AC 24
DSCP mapping for WMM background AC 8
Multiple Tx Replay Counters Disabled
Hide SSID Disabled
Deny_Broadcast Probes Disabled
Local Probe Request Threshold (dB) 0
Disable Probe Retry Enabled
Battery Boost Disabled
WEP Key 1 N/A
WEP Key 2 N/A
WEP Key 3 N/A
WEP Key 4 N/A
WEP Transmit Key Index 1
WPA Hexkey N/A
WPA Passphrase ********
Maximum Transmit Failures 25
EDCA Parameters Station profile N/A
EDCA Parameters AP profile N/A
BC/MC Rate Optimization Disabled
Rate Optimization for delivering EAPOL frames Enabled
Strict Spectralink Voice Protocol (SVP) Disabled
High-throughput SSID Profile NO-802.11n
802.11g Beacon Rate default
802.11a Beacon Rate default
Video Multicast Rate Optimization default
Advertise QBSS Load IE Disabled
Advertise Location Info Disabled
Advertise AP Name Disabled
802.11r Profile N/A
Enforce user vlan for open stations Disabled
Enable OKC Disabled

High-throughput SSID profile "NO-802.11n"
-----------------------------------------
Parameter Value
--------- -----
High throughput enable (SSID) Disabled
40 MHz channel usage Disabled
Very High throughput enable (SSID) Disabled
80 MHz channel usage (VHT) Disabled
BA AMSDU Enable Enabled
Temporal Diversity Enable Disabled
Legacy stations Allowed
Low-density Parity Check Enabled
Maximum number of spatial streams usable for STBC reception 1
Maximum number of spatial streams usable for STBC transmission 1
MPDU Aggregation Enabled
Max received A-MPDU size 65535 bytes
Max transmitted A-MPDU size 65535 bytes
Min MPDU start spacing 0 usec
Short guard interval in 20 MHz mode Enabled
Short guard interval in 40 MHz mode Enabled
Short guard interval in 80 MHz mode Enabled
Supported MCS set 0-23
VHT - Supported MCS map 9,9,9
VHT - Explicit Transmit Beamforming Disabled
VHT - Transmit Beamforming Sounding Interval 25 msec
Maximum VHT MPDU size 11454 bytes
Maximum number of MSDUs in an A-MSDU on best-effort AC 2 MSDUs
Maximum number of MSDUs in an A-MSDU on background AC 2 MSDUs
Maximum number of MSDUs in an A-MSDU on video AC 2 MSDUs
Maximum number of MSDUs in an A-MSDU on voice AC 0 MSDUs

Virtual AP profile
-------------------------------
Parameter Value
--------- -----
AAA Profile XXXXX
802.11K Profile default
Hotspot 2.0 Profile N/A
SSID Profile XXXXX
Virtual AP enable Enabled
VLAN XXXXX
Forward mode tunnel
Allowed band all
Band Steering Disabled
Steering Mode prefer-5ghz
Dynamic Multicast Optimization (DMO) Disabled
Dynamic Multicast Optimization (DMO) Threshold 6
Drop Broadcast and Unknown Multicast Enabled
Convert Broadcast ARP requests to unicast Enabled
Authentication Failure Blacklist Time 3600 sec
Blacklist Time 3600 sec
Deny inter user traffic Disabled
Deny time range N/A
DoS Prevention Disabled
HA Discovery on-association Enabled
Mobile IP Disabled
Preserve Client VLAN Disabled
Remote-AP Operation standard
Station Blacklisting Enabled
Strict Compliance Disabled
VLAN Mobility Disabled
FDB Update on Assoc Disabled
WMM Traffic Management Profile XXXXX

WMM Traffic management profile XXXXX
------------------------------------------------
Parameter Value
--------- -----
Enable Shaping Policy true
Voice Share 70 %
Video Share 10 %
Best-effort Share 10 %
Background Share 10 %

VoIP Call Admission Control profile XXXXX
-----------------------------------------------
Parameter Value
--------- -----
VoIP Call Admission Control Enabled
VoIP Bandwidth based CAC Disabled
VoIP Call Capacity 12
VoIP Bandwidth Capacity (kbps) 2000
VoIP Call Handoff Reservation 20 %
VoIP Send SIP 100 Trying Disabled
VoIP Disconnect Extra Call Disabled
VOIP TSPEC Enforcement Disabled
VOIP TSPEC Enforcement Period 1 sec
VoIP Drop SIP Invite and send status code (client) 486
VoIP Drop SIP Invite and send status code (server) 486

Any idea about what could be causing the "TCLAS flow deleted"?

Regards.

Remove your WMM traffic management profile.

Remove your VOIP Call admission control profile.

See if that fixes it.

You have too many options enabled to say what it could be.

Going along with what Colin is suggesting, are you using Airwave?  You could use the Call Volume table on the UCC Dashboard to determine if you're hitting your max of 12 simultaneous calls on an AP.

Hi all and thanks for the replies.

I removed WMM traffic management and VOIP Call admission control profiles, but the problem persists, perhaps at a slightly minor frequency.

Yes, I'm using Airwave and I've found that in some very specific cases and moments some APs gets more than 12 concurrent calls, although don't seems to correlate with the "TCLAS flow deleted" messages and it don't occurs with enough frequency to explaining the messages.

xosema,

Please PM me your email address so I can send you a link to send me your logs.tar so I can take a look and come up with a recommendation.

A call is released with reason code as TCLAS_FLOW_DELETED if AP sends ageout for the client due to inactivity.  What kind of voice clients are these (what voice protocol is in use)?  I have looked over your logs and I have a few questions...

The voice clientes are Cisco 792x IP phones using SCCP.

It's strange that the "TCLAS flow deleted" appears due to client ageout: "Station Ageout Time" is configured to 1000 seconds and I've verified that, for the same phones, several TCLAS terminations occurs frequently in intervals under that 1000 seconds, some times even in intervals of few .

Feel free to ask.

Please send me the logs of the controller with the issue.  I only got the logs for the master controller.

I've sended you the logs of the right controller now, sorry!

Hi.

Unfortunately after aplying yesterday the suggested changes (disabling the "dot11a-traffic-mgmt-profile" and "dot11a-traffic-mgmt-profile" profiles in the AP Group and enabling "Drop Broadcast and Multicast" in the other SSIDs of the same AP Group) the TCLAS messages remains. Any idea?

I'm gonna try to review the configuration both in the phones themselves as in the Call Manager searching for patterns to verify if the problem only occurs in some of them and if some kind of configuration matches the problematic ones.

Regards.

At this point, I would open a TAC case.  They can review your logs in detail and perhaps come up with a few reasons why you are having that issue.

Thanks for the advice :-)

Sorry about that...

Hi all.

I think I've found what was the problem before opening a case in the TAC. Reviewing carefully the configuration I found that the parameter "interference-immunity" in both radio profiles ("dot11a-radio-profile" and "dot11g-radio-profile") for the AP Groups that included the voice SSID was set to "3" instead of the default "2". Probably the value was changed a time ago during some tests. Since returning to the default value the TCLAS messages have dissapeared.

To change the "interference-immunity" parameter to the default value:

rf dot11a-radio-profile "TEST-a"
interference-immunity 2
!

rf dot11g-radio-profile "TEST-g"
interference-immunity 2
!

As explained for example in http://community.arubanetworks.com/t5/Technology-Blog/Hotspot-deployments-Part-II-Interference-mitigation-guidelines/ba-p/35669, the "interference-immunity" value should not changed lightly.

Regards.