Cobalt Digital COMPASS 9223-SA Dual-Channel 3G_HD_SD MPEG-4 Encoder Unit - Manual (Page 73)

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9223SA-OM (V2.0)
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FEC: Summary of the FEC configuration. If FEC is disabled, this field will indicate it as
Off. If FEC is enabled, this field will indicate the FEC matrix size as Columns × Rows,
and the protection mode as C for Column Only or R-C for Row and Column. In the
example above, Stream 1/1 has Column Only FEC with 1 Column and 4 Rows, and
Stream 2/1 has Row and Column FEC with 4 Columns and 10 Rows.
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Destination MAC: The destination MAC address for this IP Output. For multicast
destination addresses, this is derived from the destination IP address using the rules from
RFC 1112. For unicast destination addresses, this is obtained using the ARP protocol. If
this entry is the word Unknown, the 9223-SA has failed to obtain a destination MAC
address. The IP Output is
not streaming. A more detailed description of the unicast
MAC address algorithms used in the 9223-SA is presented below.
Managing Unicast MAC Addresses
When the 9223-SA is configured with a unicast destination address, it needs to obtain a
corresponding MAC address (corresponding to either the final destination, if it is in the same
subnet, or to the default gateway). These MAC addresses are obtained using the ARP protocol.
The 9223-SA uses a custom MAC address management algorithm, designed specifically for
MPEG operation.
When an IP Output stream with a unicast destination address is created, the 9223-SA
immediately starts attempting to obtain a MAC address for it, using standard ARP requests.
These requests are issued every two seconds until answered. No packets will be transmitted on
that IP Output until a MAC address can be obtained. Note that this process will happen even if
the stream is configured to be in the disabled state.
Once a MAC address is obtained, the 9223-SA will cache it for about 5 minutes, as it is usual for
IP devices. Unlike other IP devices, the 9223-SA will keep on using the MAC address until a
response is received, to avoid stream interruptions. If no response is received at that time, the
9223-SA will raise a yellow alarm. This alarm can be seen in the IP Output Statistics tab,
described in detail below.
The current state of the 9223-SA current streaming ARP cache is available in the Advanced
View of the Active IP Outputs table, described above.
IP Outputs: Statistics Tab
The Statistics tab for the IP output ports contains a summary of each stream status. There are
two sub-tabs: one for Ethernet 1, and another for Ethernet 2. The tab is depicted below: