1:1 Ip Redundancy Data Switching; Managed Switch Mode For Cdm-625A Or Cdm-625, Heights Remote Gateway, Advanced Vsat Cdm-850 Or Cdm-840, Cdm-760, Cdm-750, Cdm-710Gl, Cdm-710, Or Cdm-700 - Comtech EF Data CRS-170A Installation And Operation Manual

CRS-170A L-Band 1:1 Redundancy Switch
Introduction
will see that both faults have occurred at the same time (i.e., within a 0.5 second window), and infers
that the fault is external. Therefore, no unnecessary switchover is initiated.
1.3.2

1:1 IP Redundancy Data Switching

1.3.2.1 Managed Switch Mode for CDM-625A or CDM-625, Heights Remote
Gateway, Advanced VSAT CDM-850 or CDM-840, CDM-760, CDM-
750, CDM-710GL, CDM-710, or CDM-700
A standard, user-provided Ethernet Layer 2 Switch is needed if any of the modems listed here are
configured for Managed Switch Mode (also known as "Ethernet Bridge Mode") terrestrial traffic.
A Layer 2 Switch is designed to limit the traffic that egresses each port by only sending Ethernet packets
out the port that the destination network device is located. The switch maintains a table - known as the
dynamic Content-Addressable Memory (CAM) table - that maps MAC addresses to switch ports. When a
packet arrives, in which an entry for that specific destination MAC is unknown to the switch, it sends the
packet out all ports and waits for response packets in an attempt to identify which port that particular
MAC resides. Once the device responds, the switch is able to map the MAC to the port in the CAM table.
Any new arriving packets destined for that MAC address will be forwarded only out the port identified in
the CAM table. Most switch CAM tables do have a flush or timeout value, but is normally set to a very
high number to limit the amount of times the switch has to broadcast a packet out all ports. It is also
important to note that CAM entries for a specific port are cleared when a port link goes down.
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