FaceTime traffic is normally carried ‘best effort’ along with email, web browsing and general data traffic. But multimedia servicee like facetime are affected by delay, jitter and packet loss, FaceTime requires good end-to-end quality of service. This can be achieved by adjusting the QoS in both directions of the call to the appropriate priority
Aruba recognize events like registration sent by facetime application to Apple’s FaceTime server through its unique protocol. Once devices have been identified as multimedia capable, the mobility controller continually examines their traffic to see if it decodes as RTP, with the known characteristics of a multimedia session. RTP streams are not easily identified: There is no single field in the packet header identifying them as RTP. Aruba uses its integral stateful firewall to continuously monitor multimedia devices, scrutinizing headers for several signatures of RTP streams, and a specific template that identifies FaceTime multimedia sessions.
Aruba Controller has to use an ACL with the classify-media option enabled to identify the voice or video flow based on a deep packet inspection and analysis of the actual traffic Also setting “classify-media” in the ACL automatically enables the Application layer gateway ( ALG ) for Facetime.
Sample Configuration:
The example below shows how to configure an ACL to identify and monitor Apple Facetime traffic.
(host) (config) #ip access-list session facetime
(host) (config-sess-facetime)#any any tcp 80 permit position 1 queue low
(host) (config-sess-facetime)#any any tcp 443 permit position 2 queue low
(host) (config-sess-facetime)#any network 17.0.0.0 255.0.0.0 tcp 5223 permit position 3 queue low classify-media
(host) (config-sess-facetime)#any any UDP 80 permit position 4 queue low
(host) (config-sess-facetime)#any network 17.0.0.0 255.0.0.0 UDP 16384-16387 permit position 5 queue low
Caveat: Apple devices do not set the appropriate priority when transmitting frames, over-the-air transmissions from the Apple device towards the AP cannot be re-set until they are received, so they must still contend with other traffic.