Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 478)

ToS Switching MN/22156, rev 12
E-22 VMS User Guide
Figure E-12 Per Type ToS Switching Example
ToS Remarking
For situations where the application device is not capable of stamping a packet
with a ToS value, or where the application traffic is generated by a variety of
different hosts and protocols, ToS remarking should be considered. ToS
remarking refers to a device, such as a router, that has the capability of re-
stamping packets with a user defined ToS value. Devices that support remarking
often allow users to assign a ToS value to packets that match certain source or
destination IP addresses, port numbers, and/or protocols.
Example 1 : A user wants to switch up whenever a host performs an FTP across
the satellite. A device that supports remarking can be placed between the appli-
cations and the remote modem. The device can then be configured to stamp all
traffic that utilized FTP port 21 with a particular ToS value. The remote modem
can then be configured to detect this value and switch to a specific SCPC bit
rate.
Example 2 : A remote customer is using an IP based video encoder to transmit
video over the satellite. The encoder does not have the option to assign a ToS
value for prioritization. Again, a remarking device can be placed between the
encoder and the remote modem and configured to assign a ToS value to all
packets received from the encoder.
Figure E-13 provides an example of a router performing ToS remarking for
VoIP phones.