Comtech EF Data SLM-5650A Installation And Operation Manual page 363

Multi-TDM Tunneling Mode (ViperSat Hub or ViperSat Hub Expansion Mode
only)
Multi-TDM Tunneling is a technique where a VLAN "tunnel" is set up between the Hub unit and any
expansion units that are being used to create an SCPC link with a Remote that is Home Stated to
the specified Hub Time-Division Multiplexing (TDM) Modem.
When an Expansion unit is configured by VMS for an SCPC link, it queries its assigned hub for the
correct VLAN ID. If the feature is turned off, the Hub unit responds with a zero (0). If the feature is
enabled, the Hub will respond with a VLAN tag that is unique on the current LAN segment.
Set the Multi-TDM Tunneling Mode: Click Off, Automatic, or Manual:
•
Off – In this mode, the feature is not used and there is no VLAN tag used.
•
Automatic – In this mode, the Hub generates the VLAN tag from the last 12 bits of its IP
Address. In most cases, this will guarantee a unique value.
•
Manual – This mode SHOULD ONLY BE USED if the network is configured in such a way
that two or more hub units on the LAN segment may have the same value in the low order
12 bits of their IP Address. Once this mode is selected, a text box will appear to allow entry
of a unique ID in the range from 2 to 4095.
Click [Submit] to save the desired Multi-TDM Tunneling Mode setting.
Flow Control Enable
Use the drop-down list to set Flow Control as Enabled or Disabled. Click [Submit] to save.
Ethernet Flow Control is a technique by which the receiver sends a message to the sender to back-
off traffic once congestion is encountered.
With Flow Control Enabled, the NP Interface monitors the QOS queue depths to identify the
congestion, if any, of the QOS queue sizes. If the queue reaches 90% of the configurable QOS
queue depth, then the interface sends Ethernet Pause Frames (IEEE 802.3) with pass time 0xFFFF
to the LAN ports. Upon dropping all of the QOS depths to 50%, the interface again sends Pause
frames with pass time 0x0000 to resume the traffic back.
Proxy ARP Enable
Use the drop-down list to set Proxy ARP (Proxy Address Resolution Protocol) as Enabled or
Disabled. Click [Submit] to save.
Proxy ARP is a technique by which an NP Interface in Router Mode on a given network answers
the ARP queries for a network address that is not on this network, but is reachable via the NP
Interface.
With Proxy ARP enabled, the NP Interface (in Router Mode) 'snoops' all ARP_REQs; it will send an
ARP_REPLY (one if the ARP_REQ host address is an NP host address that is reachable via one of
the routes in the Route Table).
Appendix E
In Manual mode, it is the user's responsibility to ensure that each Hub box
on the segment is given a unique value in that range.
E–41
SLM-5650A Satellite Modem
Revision 10
MN-SLM-5650A