Technical Description of TANDBERG MCU with software version D3
D12925 Rev. 03
13
4.1.4.6 Diagnostic tools for IP
Q.931
To show Q.931 trace during a conference you need to issue the command
syslog
on
. One can get traces for RAS, Q.931 and H.245 with this command. It is a
complex trace and requires an extensive knowledge in H.323 signalling to be
understood.
Ping
Ping is used to see if the MCU is able to reach a specific IP-address, using a
mechanism in IP called ICMP. If the MCU is unable to register to its gatekeeper,
or if it is unable to dial a specific endpoint, one can use ping to see if there is at
least an IP-route to the gatekeeper or to the endpoint. In case you have problems,
one would first ping the default gateway, then the gatekeeper, and then the other
endpoint.
Traceroute
Traceroute does exactly that; it traces the route an IP-packet takes to reach its
destination and displays all router hops. Traceroute is very useful for seeing
exactly where there is a routing-problem in the IP-network, and for checking
where transport-delay is introduced.
4.1.4.7 Latency
&
Jitter
Latency
is defined as the time between a node sending a message and receipt of the
message by another node. The TANDBERG MCU can handle any value of latency-
however, the higher the latency, the longer the delay in video and audio. This may lead
to conferences with undesirable delays causing participants to interrupt and speak over
each other.
Jitter
is defined as the difference in latency. Where constant latency simply produces
delays in audio and video, jitter can have a more adverse effect. Jitter causes packets to
arrive out of order or at the wrong times, which again leads to packet loss. TANDBERG
MCU can manage packets with jitter up to 100ms. If excessive packet loss is detected,
the TANDBERG MCU will downspeed the connection until acceptable packet loss is
achieved.
4.1.4.8 Layer 4 Ports used in H.323 meetings
The following tables describes what layer 4 ports are being used by the system when call
is made on an H.323 network.
MCU me Duo Video
Function Port
Type
Gatekeeper Discovery (RAS) 1719
UDP
Q.931 Call Setup
Range 5555—5587
TCP
H.245*
Range 5555—5587
TCP
Video Range
2326—2837 UDP
Audio
Range 2326—2837
UDP
Data/FECC
Range 2326—2837
UDP
