3Com Switch 8800 Configuration Guide Chapter 16 IP Routing Protocol Overview
16-4
The Switch 8800 supports the configuration of a series of dynamic routing protocols
such as RIP, OSPF , IS-IS and BGP, as well as the static routes. In addition, the running
switch will automatically obtain some direct routes according to the port state and user
configuration.
16.2 Routing Management Policy
For the Switch 8800, you can configure manually the static route to a specific
destination, and configure dynamic routing protocol to interact with other routers on the
network. The routing algorithm can also be used to discover routes. For the configured
static routes and dynamic routes discovered by the routing protocol, the Switch 8800
implements unified management. That is, the static routes configured by the user are
managed together with the dynamic routes discovered by the routing protocol. The
static routes and the routes learned or configured by different routing protocols can also
be shared with each other.

16.2.1 Routing Protocols and the Preferences of the Corresponding Routes

Different routing protocols (as well as the static configuration) may generate different
routes to the same destination, but not all these routes are optimal. In fact, at a certain
moment, only one routing protocol can determine a current route to a specific
destination. Thus, each of these routing protocols (including the static configuration) is
set with a preference, and when there are multiple routing information sources, the
route discovered by the routing protocol with the highest preference will become the
current route. Routing protocols and the default preferences (the smaller the value is,
the higher the preference is) of the routes learned by them are shown in Table 16-1.
In the table, 0 indicates a direct route. 255 indicates any route from unreliable sources.
Table 16-1 Routing protocols and the default preferences for the routes learned by
them
Routing protocol or route type The preference of the corresponding
route
DIRECT 0
OSPF 10
IS-IS 15
STATIC 60
RIP 100
OSPF ASE 150
OSPF NSSA 150
IBGP 256
EBGP 256