2
Static routes are easy to configure and require less system resources. They work well in small and stable
networks. In networks where topology changes may occur frequently, using a dynamic routing protocol
is better.
To display brief information about a routing table, use the
display ip routing-table
command:
<Sysname> display ip routing-table
Routing Tables: Public
Destinations : 7 Routes : 7
Destination/Mask Proto Pre Cost NextHop Interface
1.1.1.0/24 Direct 0 0 1.1.1.1 Vlan11
2.2.2.0/24 Static 60 0 12.2.2.2 Vlan12
80.1.1.0/24 OSPF 10 2 80.1.1.1 Vlan13
…
A route entry includes the following key items:
•
Destination
—IP address of the destination host or network.
•
Mask
—Mask length of the IP address.
•
Pre
—Preference of the route. Among routes to the same destination, the one with the highest
preference is optimal.
•
Cost
—If multiple routes to a destination have the same preference, the one with the smallest cost is
the optimal route.
•
NextHop
—Next hop.
•
Interface
—Output interface.
Dynamic routing protocols
Dynamic routing protocols dynamically collect and report reachability information to adapt to topology
changes. They are suitable for large networks.
Compared with static routing, dynamic routing protocols require more resources, and are complicated to
configure.
Dynamic routing protocols can be classified based on different criteria, as shown in
:
Table 2
Dynamic routing protocols
Criterion Categories
Optional scope
•
Interior gateway protocols (IGPs)
—Work within an AS. Examples include RIP, OSPF,
and IS-IS.
•
Exterior gateway protocols (EGPs)
—Work between ASs. The most popular one is
BGP.
Routing algorithm
•
Distance-vector protocols
—RIP and BGP. BGP is also considered a path-vector
protocol.
•
Link-state protocols
—OSPF and IS-IS.
Destination address
type
•
Unicast routing protocols
—RIP, OSPF, BGP, and IS-IS.
•
Multicast routing protocols
—PIM-SM and PIM-DM.
IP version
•
IPv4 routing protocols
—RIP, OSPF, BGP, and IS-IS.
•
IPv6 routing protocols
—RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS.