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C.4.3 a daisy chain capability, C.4.4 in-band control, C.4.5 internal buffer and flow control throttle – Comtech EF Data MDX420 SkyWire Manual User Manual

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MDX420 SkyWire™ Satellite Network Gateway

SkyWire QoS

MN-MDX420 Revision 6

C–9

C.4.3 A Daisy Chain Capability

For large networks that require more than 4 carriers, the ability to daisy chain multiple SkyWire
Gateways together provides a simple upgrade path. As your network grows, an addition SkyWire
Gateway with up to four burst demodulators can be added to the chain without having to buy
additional blades for your router or update the routing table to allow for multiple return paths.
From your routers point of view, there will still only be a single one wire path to and from all of the
destinations. Despite the fact that the outbound satellite path and some of the satellite return
paths go through two boxes.

C.4.4 In-band Control

For users who wish to monitor and control the remote end of a link, SkyWire provides an internal
connection between the normal data path and the M&C. When this capability enabled, the
Ethernet SNMP commands and responses to the far side ride along with the rest of the data
traffic. At the far end they are internally passed to and from the M&C without requiring an
external connection between the data port and the M&C port. Security for the control information
that is riding along with the user traffic is provided by using SNMP version 3.

For users who never want to mix their control information with user traffic, disabling this feature
breaks the internal connection. In this case, Ethernet control of the M&C can only be
accomplished by using one of the M&C RJ-45 Control ports on the gateway.

C.4.5 Internal Buffer and Flow Control Throttle

SkyWire provides 120K bytes of internal data storage for buffering of Ethernet traffic. When this
buffer is almost full, if flow control is enabled, SkyWire will attempt to slow down the incoming
terrestrial data to prevent the buffer from being overrun. It does so using industry standard
backpressure on half duplex links and an IEEE 802.3x Pause Frame on full duplex links.
Together the combination of the buffer and flow control can provide an effective rate exchange
and throttle between the Ethernet ports and the satellite link.