I have a QOS configuration for interactive video among other queues.
class-map match-any QOS-INTERACTIVE-VIDEO
match ip dscp af41 af42
match protocol rtp video
match protocol ms-lync-video
match protocol skype
match protocol h323
match protocol rtcp
match protocol ms-teams-video
A user on the network has Skype for Desktop installed on a MAC. When the user was on a video call I noticed the counters for rtcp being hit heavily. For example, I started monitoring shortly after the call started... No other voice/video calls occured except one I made on Microsoft Teams to a colleague at the time as a test for utilization of the queue.
#show policy-map interface ethernet 0 output class QOS-INTERACTIVE-VIDEO
Ethernet0
Service-policy output: QOS-EGRESS
queue stats for all priority classes:
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 662756/364269137
Class-map: QOS-INTERACTIVE-VIDEO (match-any)
323201 packets, 291869126 bytes
5 minute offered rate 3383000 bps, drop rate 0000 bps
Match: ip dscp af41 (34) af42 (36)
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol rtp video
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol ms-lync-video
21 packets, 5224 bytes
5 minute rate 0 bps
Match: protocol skype
23374 packets, 13593864 bytes
5 minute rate 7000 bps
Match: protocol h323
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol rtcp
193572 packets, 160132444 bytes
5 minute rate 2106000 bps
Match: protocol ms-teams-video
106234 packets, 118137594 bytes
5 minute rate 1278000 bps
Priority: 15% (3390 kbps), burst bytes 84750, b/w exceed drops: 154
The user was on the call for about 20 minutes and these are the counters near the end
#show policy-map interface ethernet 0 output class QOS-INTERACTIVE-VIDEO
Ethernet0
Service-policy output: QOS-EGRESS
queue stats for all priority classes:
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 790148/468967730
Class-map: QOS-INTERACTIVE-VIDEO (match-any)
449633 packets, 396362739 bytes
5 minute offered rate 2836000 bps, drop rate 0000 bps
Match: ip dscp af41 (34) af42 (36)
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol rtp video
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol ms-lync-video
21 packets, 5224 bytes
5 minute rate 0 bps
Match: protocol skype
23694 packets, 13797267 bytes
5 minute rate 0 bps
Match: protocol h323
0 packets, 0 bytes
5 minute rate 0 bps
Match: protocol rtcp
319684 packets, 264422654 bytes
5 minute rate 2419000 bps
Match: protocol ms-teams-video
106234 packets, 118137594 bytes
5 minute rate 422000 bps
Priority: 15% (3390 kbps), burst bytes 84750, b/w exceed drops: 154
You'll notice the usage of rtcp! FYI, I have rtp audio in a different queue per this config and it was not being hit by Skype
class-map match-any QOS-VOICE
match ip dscp ef
match ip dscp cs5
match protocol rtp audio
match protocol ms-lync-audio
match protocol ms-teams-audio
According to my understanding rtcp should not see much traffic. quoting the following link "RTP and RTCP. RTP is used for transfer of multimedia data, and the RTCP is used to periodically send control information and QoS parameters"
https://en.wikipedia.org/wiki/Real-time_Transport_Protocol
I have the latest available nbar protocol pack installed on C887VAM-K9 running version 15.6(3)M4
Loaded Protocol Pack(s):
Name: Advanced Protocol Pack
Version: 32.1
Publisher: Cisco Systems Inc.
NBAR Engine Version: 23
Creation time: Tue Nov 14 09:42:31 UTC 2017
File: flash:pp-adv-isrg2-156-3.M-23-32.1.0.pack
State: Active
My question is: Besides Skype for Desktop MAC doing this, is there a way I can get skype out of the rtcp queue so it doesn't affect legitimate rtcp traffic? And allow me to better manage Skype for Desktop calls - say for example... putting it in its own queue altogether? I haven't tested Skype for Desktop on Windows or Linux to see if they behave the same yet.
