Cisco Cisco Expressway Manual De Manutenção
Configuring the Traversal Subzone Ports
On Configuration > Traversal Subzone you can configure the range of ports used for media in traversal calls.
What is a valid range to use?
You can define the media port range anywhere within the range 1024 to 65533. Traversal media port start must be
an even number and Traversal media port end must be an odd number, because ports are allocated in pairs and the
first port allocated in each pair is even.
an even number and Traversal media port end must be an odd number, because ports are allocated in pairs and the
first port allocated in each pair is even.
How big should the range be?
Up to 48 ports could be required for a single traversal call, and you can have up to 100 concurrent traversal calls on a
small/medium system, or 500 concurrent traversal calls on a large system. The default range is thus 48*500 = 24000
ports.
small/medium system, or 500 concurrent traversal calls on a large system. The default range is thus 48*500 = 24000
ports.
If you want to reduce the range, be aware that the Expressway will raise an alarm if the range is not big enough to
meet the nominal maximum of 48 ports per call for the licensed number of rich media sessions. You may need to
increase the range again if you add new licenses.
meet the nominal maximum of 48 ports per call for the licensed number of rich media sessions. You may need to
increase the range again if you add new licenses.
Why are 48 ports required for each call?
The nominal maximum number of ports allocated per call = max number of ports per allocation * max number of
allocation instances. This is 8 * 6 = 48, and those numbers are derived as follows:
allocation instances. This is 8 * 6 = 48, and those numbers are derived as follows:
Each call can have up to 5 types of media; video (RTP/RTCP), audio (RTP/RTCP), second/duo video (RTP/RTCP),
presentation (BFCP), and far end camera control (H.224). If all these media types are in the call, then the call requires
8 ports; 3 RTP/RTCP pairs, 1 for BFCP, and 1 for H.224.
presentation (BFCP), and far end camera control (H.224). If all these media types are in the call, then the call requires
8 ports; 3 RTP/RTCP pairs, 1 for BFCP, and 1 for H.224.
Each call has at least two legs (inbound to Expressway and outbound from Expressway), requiring two instances of
port allocation. A further four instances of allocation are required if the call is routed via the B2BUA. In this case, ports
are allocated at the following points:
port allocation. A further four instances of allocation are required if the call is routed via the B2BUA. In this case, ports
are allocated at the following points:
1.
Inbound to the local proxy from the source
2.
Outbound from the local proxy to the local B2BUA
3.
Inbound to the local B2BUA from the local proxy
4.
Outbound from the local B2BUA to the local proxy
5.
Inbound to the local proxy from the local B2BUA
6.
Outbound from the local proxy to the destination
Figure 12: Maximum port allocation for a media traversal call
In practice, you probably won't reach the maximum number of concurrent traversal calls, have them all routed
through the B2BUA, and have all the possible types of media in every call. However, we defined the default range to
through the B2BUA, and have all the possible types of media in every call. However, we defined the default range to
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Cisco Expressway Administrator Guide