Q-Flex Satellite Modem Installation and Operating Handbook
7-30
7.8.10 Static and Dynamic Routing
The modem can be operated as a two-port static router, one port being the terrestrial
interface and the other port being the satellite interface. Static routing is useful for small
networks that do not require dynamic routing – it can be activated by selecting routing
mode but not enabling any dynamic routing protocols (static routing is provided as a free
feature).
Each route comprises a
Destination IP Address, Subnet Mask
and a
Gateway Address.
If
the destination address of a packet fails to match any entries in the routing table, and the
packet has a destination address outside of the local network, the packet will be sent to
the default gateway, if specified, otherwise the packet will be discarded. (Static routes can
also be entered, and the whole routing table displayed, via the telnet interface to Zebra
within the Quagga Router when in Routing Mode The Zebra interface
is not dissimilar to
Cisco’s command line interface and is described in
the Quagga user manual available
from
http://www.quagga.net/docs/quagga.pdf
.)
Dynamic routing in the modem offers support for RIP V1 and V2, OSPF V2 and V3 and
BGP V4. Note that the 64 static routes have precedence over dynamic routes.
When dynamic routing is on, traffic will be automatically routed across satellite correctly
by automatic exchange of routing information with other routers. The routing information
exchange uses satellite bandwidth and is therefore an overhead. The amount of
bandwidth required depends on the size of the routing tables that are exchanged and the
frequency with which they are exchanged.
Dynamic routing is supported via the Quagga software package. Itan only be used on
point-to-point links. It is possible to enable routing, TCP acceleration and traffic shaping
together at the same time (but routing is incompatible with the header compression
feature).
Configuration of dynamic routing protocols can be complex and for this reason the
modem provides only a default configuration for the RIP and OSPF protocols that can be
enabled from the user interfaces. These will be all that is required in many cases. Further
configuration of all routing protocols is available for expert users, via a telnet interface to
the
Quagga
software
(the
Quagga
user
manual
available
from
http://www.quagga.net/docs/quagga.pdf
). You can telnet into a different command line
interpreter for setting up each routing protocol and one that can be used for basic-level
setup of all routing protocols. These provide ‘Cisco IOS-like’ commands that will be
familiar to users of Cisco equipment.
When using telnet to login to the Quagga (the default password is ‘paradise’) various port
numbers are used to access the routing protocol to be configured, as follows:
•
RIP: port 2602
•
OSPF: port 2604
•
BGP: port 2605
•
Zebra: port 2601
