Principle and configuration of static routing
1. Routing
Routing: The process of forwarding from the source host to the target host.
The criteria for selecting the optimal route:
1. The most preferred match for the longest subnet mask.
2. Select the most preferred match with the smallest priority in the routing protocol.
DIRECT:0
OSPF:10
IS-IS:15
STATIC:60
RIP:100
OSPF ASE:150
OSPF NSSA:150
IBGP:256
EBGP:256
3. In the case of the same routing protocol, select the highest priority match with the smallest metric value.
The metric value of each protocol is defined differently. Static routing is related to the routing priority. This is manually specified. The RIP protocol is related to the number of hops. The smaller the number of hops, the higher the priority. The OSPF protocol is related to bandwidth. The maximum bandwidth is the highest priority. The metric is used to determine the quality of the link.
4. If none of the above routes can match, match the default route.
The default route is a special form of static route. It belongs to a kind of static route. It is conditional to use it and can only be used in the stub network.
Floating routing refers to the configuration of two static routes. The default link quality (high bandwidth) is selected as the main path. When the main path fails, the backup route with smaller bandwidth will replace it to keep the network uninterrupted.
Static routing protocols can only be used in small-scale corporate networks, while large-scale corporate networks use dynamic routing protocols. Static routing advantages: flexible configuration, manual configuration by the administrator, saving link costs.
Disadvantages of static routing: When the topology changes, the administrator needs to go to each router to modify the routing configuration. It is recommended to use static routing protocol for external routes within five, and dynamic routing protocol for more than five external routes.
Static routing features: small network use, does not occupy bandwidth, needs to be manually configured by the administrator, one-way, lack of flexibility
2. Routing table
The routing table is a collection of routing entries maintained in the router, and the router makes path selection according to the routing table
The routing table forms
1. Directly connected network segments. Configure IP address, port UP state, form direct route
2. Indirect network segment. For non-directly connected network segments that require static routing or dynamic routing, add the network segment to the routing table
3. Classification of routing protocols
Routing protocol:
1. Static routing-the administrator manually configures the routing.
2. Dynamic routing-automatically learn routing between routers.
In the local area network-GP (Interior Gateway Routing Protocol)-RIPV1, RIPV2, EIGRP (DV) distance vector routing protocol, OSPF, ISIS (LS) link state routing protocol
Internet-EGP (External Gateway Routing Protocol)-BGPV4 (version four )﹒
int g0/0/0
ip address 10.1.1.3 24
undo shutdown
ip address 10.1.2.3 24
undo shutdown
ip route-static 192.168.1.0 24 10.1.1.2
(Configure static route) The next hop of the subnet mask of the target network segment
ip route- static 172.16.1.0 24 10.1.2.4
4. The default route
When the router cannot find the routing entry of the target network in the routing table, the router forwards the request to the default routing interface
stub network: stub network
Default routing is a special form of static routing, it belongs to a kind of static routing, and can only be used in stub/stub network
5. Floating routing
Refers to the configuration of two static routes. The route with good quality (large bandwidth) is selected by default. When the main route fails, the backup route with smaller bandwidth will replace it to keep the network uninterrupted.
/32: Host route
| R1 |
|---|
| int LoopBack 0 |
| ip address 1.1.1.1 32 |
| int g0/0/0 |
| ip address 12.1.1.1 24 |
| undo shutdown |
| int e0 / 0/0 |
| ip add 21.1.1.1 24 |
| undo shutdown |
| display ip routing-table (view routing table) |
| ip route-static 0.0.0.0 0.0.0.0 21.1.1.2 preference 61 (Priority 61. Because all default routes can be used at the end) |
| Criteria when selecting the optimal route: |