Specifications
EASTAR UHP-1000 SERIES SATELLITE ROUTER
INSTALLATION AND OPERATION MANUAL, V. 2.3
(SW VERSION 2.2.9)
© ROMANTIS 2010 36 www.romantis.com
main Table, with VLAN=0), having IP-address entered into route Table of this VLAN.
Decide how to route this traffic over to satellite, having map commands entered into
Table of this VLAN and SVLAN number for transmission.
Mix traffic from various VLANs, routing IP networks from VLAN routing tables into the
same SVLAN.
Direct traffic from one VLAN by separate routes into different SVLANs.
The command routing IP network to SVLAN always features one of the four priorities
(Low, Med, High, and DSCP), so the user can route networks for transmission with
different priorities to the same SVLAN.
On the other end of the channel:
Decide to which routing table of (which VLAN) to receive SVLAN from the satellite.
Decide where route it afterwards (to LAN) with VLAN tagging of this Table (or
without tagging if the main Table with VLAN=0 performed reception).
2.8.5 IP traffic screening
Satellite channels by nature are broadcasting. In this case in a point-to-multipoint topology
network, IP-packets transmitted to the satellite from Hub can be received on many
terminals simultaneously. Since different networks are routed to different terminals, it is
logical that each SVLAN be assigned to a separate direction, and this is what is usually
done. But it may happen so that due to the router wrong configuration or in case of mixing
routers traffic into one SVLAN (e.g. into SVLAN 0 for a better channel efficiency), not all
traffic received via SVLAN will be lead out from the router to LAN (there will be no routes).
If in this case the default route on the router is set to the Central Station, a rooting loop
may be generated, the result being that channels will be instantly overloaded with
circulating packets.
To avoid this situation, UHP-1000 router is provided with a special mechanism - IP
screening. This mechanism works as follows: each packet received from satellite gets a tag.
If during routing this packet tries to go back to the satellite it will be dropped. Packets
coming from LAN and generated by the router itself are not tagged and they have no
limitations whatsoever.
Modulator
Demodulator
Local IP stack
LAN
IP router
ip map 0.0.0.0 /0 ml 0
svlan receive demod 0
SVLAN encapsulation
SVLAN decapsulation
Figure 18 IP traffic screening
Router statistics (sh ip) is provided with a counter indicating how many packets have been
dropped because of screening.
Packets directed to the modulator are at first encapsulated in SVLAN and then are placed
into of the three priority queues LOW, MED, HIGH. There is the fourth queue with a still
higher priority but it is used for service traffic and signaling. The queues work using a
"hard‖ priority, i.e. packets from a lower priority queue are transmitted only when a higher-
priority queue is empty.