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
Figure 1-4. 1:1 IP Redundancy Managed Switch Mode for CDM-625A or CDM-625, Heights
Remote Gateway, Advanced VSAT CDM-850 or CDM-840, CDM-760, CDM-750,
Figure 1-4 shows a Managed Switch Mode 1:1 IP Redundancy setup with the Ethernet data interface of both
modems connected to a Layer 2 Switch. Both modems are operational – Modem 'A' is Online and connected
to Port 4 of the Layer 2 Switch. Modem 'B' is Offline and connected to Port 3 of the Layer 2 Switch, but the
Ethernet link is not active because only the Online unit will have an active Ethernet data interface. Also, Local
PC 'A' is connected to Port 1 of the Layer 2 Switch.
When Ethernet traffic is sent from Local PC 'A' across the satellite link to remote PC 'B', the Layer 2
Switch will "learn" the MAC addresses of both PCs and will have these dynamic entries in its CAM Table:
Port 1 MAC 00-00-00-00-00-11 (Local PC 'A')
Port 3 No entries, port down
Port 4 MAC 00-00-00-00-00-22 (Remote PC 'B')
As shown in Figure 1-5, in the event of a fault on the Online unit 'A', the following will occur:
•
Modem 'A' goes offline and disables its Ethernet data interface.
•
Simultaneously, Modem 'B' goes online and enables its Ethernet data interface.
•
Layer 2 Switch 'A' senses that Port 4 is no longer active and clears the CAM table entries for that
port.
•
When the next Ethernet packet from Local PC 'A' destined for Remote PC 'B' arrives at Switch
'A', there is no CAM entry for the PC 'B' MAC, so it will be broadcast to all active ports.
•
When the next Ethernet packet from Remote PC 'B' arrives at Switch 'A', Switch 'A' dynamically
adds the PC 'B' MAC to the CAM table for Port 3.

CDM-710GL, CDM-710, or CDM-700

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MN/CRS170A.IOM
Revision 14