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CDD-880 Multi Receiver Router
Appendix C
User traffic on the Traffic ports does not require CDRP, as BPM automatically and seamlessly
handles ACM/VCM for this traffic.
When operating the network with the Comtech NetVue or Vipersat Management System (VMS),
the Advanced VSAT units (CTOG-250/CDM-800, CDM-840, and CDD-880) are managed through
the Management Network using the Management Ethernet port and Management IP Addresses.
C.4
IEEE 802.1Q Support
Advanced VSAT support for IEEE 802.1Q includes VLAN Trunking, Access Mode and Multiple
VLAN Tagging support.
C.4.1 VLAN Trunking
The Advanced VSAT Hub equipment always functions in VLAN Trunking Mode. Trunking Mode
means that Ethernet packets received by the CTOG-250 LAN-1 interface are passed, unchanged
and unfiltered, to the appropriate remote modem.
Likewise, when the CDM-840 is in Trunking Mode, the VLAN tags are passed, unchanged and
unfiltered, through the modem.
The CDD-880 is a receive-only pass-through in BPM Mode. As such, it receives the packets from
the remotes and passes them to the CTOG-250 for processing and forwarding.
C.4.2 Access Mode Support
As part of 802.1Q support, the CDM-840 supports Traffic port configuration in either Trunk or
Access Mode. Access Mode allows the CDM-840 to function as a VLAN edge switch to add and
remove VLAN tags to connect a distant end network with other networks.
•
All packets received at the Traffic Ethernet port are tagged with the assigned Access Port
VLAN ID.
•
All packets having the matching VLAN ID that are then received from the WAN have the
VLAN tag removed, and the packets are passed out the Traffic LAN port.
•
In Access Mode, the CDM-840 drops all packets that already have VLAN tags that it receives
at its Traffic LAN port.
•
In Access Port Mode, packets that do not have a matching VLAN ID that are received from
the WAN are dropped.
(Note that this is not normal behavior as, once the MAC addresses have been learned at a
given remote, all other remotes will then perform a hardware-level filter on the packets.)
C–6
MN-CDD880
Revision 2
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