1. Static Routing Configuration
basic concept of
static route is a route information configured by the user or network administrator. When the state of the network topology or link changes, the network administrator needs to manually modify the static routing table associated with the routing information. Static routing information by default is private and will not be passed to other routers. Of course, the network administrator can also set the router to become shared. Static routing is generally applicable to simple network environment, in this environment, network administrators easy clear understanding of the network topology, easy to set the correct routing information.
Pros:
Another benefit of using static routing is that network security is high. Since dynamic routing exchange their routing tables between routers need frequent, and the analysis of the routing table can reveal information about the network topology and network addresses and the like. Therefore, the network for security reasons also can configure static routes. Do not take up network bandwidth, because no static routing update traffic.
Disadvantages:
large and complex network environments generally should not use static routing. On the one hand, the network administrator is difficult to fully understand the topology of the entire network; on the other hand, when the network topology and link state changes, the router static routing information in a wide range of needs adjustment, the difficulty of this work and complexity is very high.
Static Routing Configuration Commands
router (config) #hostnameA (to change the router hostname) A (config) # interfacef0 / 0 ( Enter interface F0 / 0)
A (config-IF) # ipaddress192.168.1.1 255.255.255.0 (Set the interface ip address and subnet mask code)
A (config-IF) #noshutdown (enable Interface)
A (config) # interfacef0 /. 1
A (config-IF) # ipaddress192.168.2.1 255.255.255.0
A (config-IF) #noshutdown
A (config) # iproute192.168.3.0 255.255.255.0f0 / 1 (the destination network segment address of the destination subnet mask ip exit interface (router A))
router (config) #hostnameB
B (config) # interfacef0 / 0
B (config-IF) # address192.168.3.1 255.255.255.0 IP
B (config-IF) #noshutdown
B (config) # interfacef0 /. 1
B (config-IF) #ip address192.168.2.2 255.255.255.0
B (config-IF) #noshutdown
B (config) # iproute192.168.1.0 192.168.2.1 255.255.255.0
r1 port:
Router> EN
Router#config//进入配置模式Configuring from terminal,memory,or network[terminal]?t Enter configuration
commands,one perline.End with CNTL/Z.
Router (config) # hostnamer1 // Change the host name r1
r1 (config) # intf0 / 0 // Configure port f0 / 0
r1 (config-if) # ipadd192.168.1.1255.255.255.0 // Set the port ip
r1(config-if)#noshut//打开端口%LINK-5-CHANGED:Interface Fast Ethernet1/0,changed state to up
r1(config-if)#%SYS-5-CONFIG_I:Configured from console by console
r1 (config) # intf1 / 0 // Configure port f1 / 0
r1 (config-if) # ipadd192.168.2.1255.255.255.0 // Set the port ip
r1 (config-if) # noshut // open the port% LINK-5-CHANGED: Interface Fast Ethernet1 / 0, changed state to up the router r2 Port
Router (config) #hostname
route types and characteristics of
routes into static routes, default routing and dynamic routing.
① static routing fixed routing manually configured by the administrator in the router. Static routing allows routing behavior for precise control, reducing network traffic (dynamic routing needs to send a message periodically to maintain the relationship), and having a unidirectional configuration is simple. Under normal circumstances, a higher priority than static routing dynamic routing.
② default route is a static route, which is generated when the routing table entry used by routers between the routing table with the target address of the packet does not match.
The default routing configuration commands are as follows:
router (config) # ip route 0.0.0.0 0.0.0.0 next-hop address
router（config）# ip classless
Wherein 0.0.0.0 0.0.0.0 representatives will be sent to any network packets are forwarded to the next hop.
Ip classless refer to a router can not forward the received packets when it will be matched to the default route. Otherwise usually it will drop the packet and return an ICMP unreachable destination address message.
③ is between the dynamic routing network routers, network topology in real time in accordance with changes in mutual transmission of information, the received information is calculated by using the routing protocol, routing table generated or updated in the process.
Dynamic routing reduces administrative tasks but take up network bandwidth.
Common routes include dynamic distance vector routing protocol (e.g., RIP) and link state routing protocols (e.g. OSPF).
Configuring 2.RIP
Basic Concepts
Routing Information Protocol RIP is a distributed based on distance vector routing protocol is an internal gateway protocol. RIP agreement "distance" also known as "hops" because each through a router hop count is incremented. Agreement provides for an autonomous system (AS) routers in child every 30 seconds will exchange messages with neighboring routers to dynamically establish routing table. When transmitting data, RIP will select a route having a minimum router.
RIP algorithm
sent from each neighboring router RIP messages, perform the following steps:
(1) address of the adjacent router X RIP packet sent, to modify all items in this telegram: the "under hop "field X address is changed, and all the" distance value plus 1. each item "key has three data fields, namely: the destination network N, the distance d, is the next-hop router X .
(2) RIP packets in each of the modified item, the following steps:
- If the routing table is not the original purpose of the network N, put the item is added to the routing table,
- If the next-hop router address is X, put the project received the routing table to replace the original project
- If the items are received is less than the distance d from the routing table is updated
(3) if three minutes have not received adjacent routers update routing tables, neighboring routers referred to put this unreachable routers, i.e., the distance is set to 16.
(4) returns.
Characteristics of rip
1. hop limit
RIP is designed for a relatively small autonomous systems. As a result, it imposes a strict limit on the number of hop hop 15. When the packet is forwarded by the routing device, which hops counter which will add cost to be forwarded link. If the number of hops to the value after 15, the message still did not reach its destination address, the destination is considered unreachable and the packet is discarded.
2. Fixed a measure
of the number of hops for the next discussion of a fundamental limitation of the study RIP made good bedding, this limitation is: fixed cost metric. Although the cost metric can be configured by the administrator, but they are essentially static. RIP can not update them in real time to adapt to changes in the network encountered. Takes measures defined by the administrator remain unchanged until updated manually.
3. Slow convergence
from a human point of view, wait for 30 seconds once the update is not inconvenienced. However, routers and computers to run much faster than human speed. We had to wait 30 seconds update there is no obvious adverse consequences. Than just wait 30 seconds once the update is more damaging had to wait 180 seconds set aside a route. And this is only the beginning of a router the amount of time required for convergence. Depends on the number of routers and their interconnection topology, you may need to repeat the update to fully converge on the new topology. RIP router slow convergence will create many opportunities such invalid routes still erroneously broadcast as valid route
4. reacted strongly to the routing table update
RIP node 30 seconds of inactivity intervals circumferentially broadcast its routing table. In large networks with many nodes, this will consume a considerable amount of bandwidth.
5. Lack of load balancing
another RIP is its lack of clearly insufficient dynamic load balancing capabilities. FIG. 19 shows a case to another router has two serial links. Ideally, the router will try to figure equal distribution of traffic in two serial links. This makes minimizing congestion on the two links, and optimize performance.
6.RIP easy to configure, flexible and easy to use
RIP configuration commands
ip Protocol Show
Show ip route
in the global settings mode:
1. Start RIP routing
Router RIP
2. Configure RIP routing subnet
network subnet address
3. RIP routing broadcast allow non-broadcast type network
neighbor port adjacent neighboring routers IP address
4. Configure RIP versions of
RIP routing protocols in two versions, when the routers connected to other vendors, note the version to be consistent, by default, the Cisco router receives a routing information and RIP Version 2, but only one version of the transmitted routing information, provided the RIP version vesion 1 or 2. further, the control may be a particular version of a specific port to send or receive routing information
3.RIP + static routing entire network interworking
Configuring R1, R2, R3, R4 basic IP
Do R2, R3, R4 Rip the 
configuration R1, R4 is the loopback interface
R2 configure static routes on 
doing the introduction of static, R2 R3 R4 192.168.1.0 learning 
tests it possible to ping