3Com 5500-SI Routing Management Policy

IP Routing Protocol Overview 219
Figure53 The routing table
Routing Management
Policy
The Switch 5500 supports the configuration of a series of dynamic routing protocols
such as RIP and OSPF, as well as static routes. The static routes configured by the user
are managed together with the dynamic routes as detected by the routing protocol.
The static routes and the routes learned or configured by routing protocols can be
shared with each other.
Routing Protocols and Route Preferences
Routing protocols (including static configurations) can 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 single
destination. Thus, each routing protocol (including static configurations) has a set
preference, and when there are multiple routing information sources, the route with
the highest preference becomes the current route. Routing protocols and the default
preferences of the routes that they learn are shown in Table197. Th e smaller the
value, the higher the preference).
In Table197, 0 indicates a direct route, and 255 indicates any route from an
unreliable source.
Except for direct routing and BGP (IBGP and EBGP), the preferences of various
dynamic routing protocols can be manually configured to meet the user
requirements. The preferences for individual static routes can be different.
Forwarding Port
router passed
10.0.0.0 Directly
11.0.0.0
12.0.0.0 11.0.0.2
13.0.0.0 3
14.0.0.0 13.0.0.2 3
15.0.0.0 10.0.0.2 2
16.0.0.0 10.0.0.2 2
15.0.0.0
16.0.0.0
10.0.0.0
13.0.0.0
12.0.0.0
14.0.0.0 11.0.0.0
R4
R1
R3
R2
R6
R5
R7
R81
11.0.0.2
2
12.0.0.1
12.0.0.2
12.0.0.3
14.0.0.1
14.0.0.2
13.0.0.1 13.0.0.4 11.0.0.1
3
10.0.0.1
10.0.0.2
16.0.0.3
16.0.0.2
15.0.0.2
15.0.0.1 13.0.0.2
16.0.0.2
13.0.0.3
The routing table of router R8
Destination
host
location
Directly
Directly
2
1
1
Forwarding Port
router passed
10.0.0.0 Directly
11.0.0.0
12.0.0.0 11.0.0.2
13.0.0.0 3
14.0.0.0 13.0.0.2 3
15.0.0.0 10.0.0.2 2
16.0.0.0 10.0.0.2 2
15.0.0.0
16.0.0.0
10.0.0.0
13.0.0.0
12.0.0.0
14.0.0.0 11.0.0.0
R4
R1
R3
R2
R6
R5
R7
R81
11.0.0.2
2
12.0.0.1
12.0.0.2
12.0.0.3
14.0.0.1
14.0.0.2
13.0.0.1 13.0.0.4 11.0.0.1
3
10.0.0.1
10.0.0.2
16.0.0.3
16.0.0.2
15.0.0.2
15.0.0.1 13.0.0.2
16.0.0.2
13.0.0.3
The routing table of router R8
Destination
host
location
Directly
Directly
2
1
1
Table197 Routing Protocols and the Default Preferences for Routes
Routing protocol or route type The preference of the corresponding route
DIRECT 0
OSPF 10
ISIS 15
STATIC 60
RIP 100
OSPF ASE 150
OSPF NSSA 150
IBGP 256
EBGP 256
UNKNOWN 255