Zhone Technologies 800 - Manual (Page 112)

5-6 IMACS System Release 5.1.6 Server Cards
Model No. Running Head IPR WAN Routing IPR Card
5.4 IPR WAN Routing
IPR is designed to provide a maximum level of flexibility to users with different IP WAN
topology requirements. IPR supports hub-and-spoke topology, partially or fully meshed
topology, point-to-point IP interfaces, multi-point IP interface, unnumbered IP interfaces or a
combination of any of the above. Figure 5-4 shows the Hub-to-Spoke Topology.
5.4.1 Hub-and-Spoke
The Hub-and-Spoke topology is that every “regional” (spoke) router has to go through the
same “central-office: (hub) router for every destination IP node that is not local to a spoke
router. This topology is very simple to configure: All spoke routers have a hub router as their
default gateway (Default gateway is a router that IP nodes go to if they do not know a path to
a particular IP network). Hub can be completely passive (from a routing protocol point of
view), advertising no routes to spoke router, and the spoke router can be configured with
default point at the hub. A spoke router, in its turn, will advertise any locally known or
discovered IP networks (if any) through any routing protocol, since routing convergence time
is irrelevant. IPR can be both a spoke and/or a hub router.
Figure 5-4. Hub-and-Spoke Topology
"Spoke" Router
Central Side
"Hub" Router
"Spoke" Router
"Spoke" Router
"Spoke" Router