Dynamic routing
Overview of dynamic routing
Dynamic routing
based on a certain routing protocol
Dynamic routing features
reduce management tasks and
occupy network bandwidth
After configuring the interface IP address, a direct route is generated in the routing table.
Dynamic routing does not need to write routes manually, and routers can learn from each other by themselves
Routing table formation
When the router learns the direct route
, the router will send the routing table to its neighbors when the
update cycle is up to 30s. After another 30s, the second update cycle will send the routing table again.
Dynamic routing protocol
Overview of Dynamic Routing Protocol
The language used to exchange information between routers
Metric value
Hops, bandwidth, load, delay, reliability, cost The router will determine the optimal routing path through the metric value
Convergence The process of
bringing all routing tables to a consistent state
Comparison
of static routing and dynamic routing Static routing and dynamic routing complement each other in the network
Dynamic routing protocol classification
According to the routing algorithm classification
Distance vector routing protocol
Route
RIP1/2, BGP (Path Vector Protocol), EIGRP (Advanced Distance Vector Protocol) based on the number of routers passing from the source network to the target network. Routers
do not fully understand the topology of the entire network. It is the "legendary route". A sends routing information to B, and B adds its own metric and sends it to C. The entries in the routing table are audible
Link state routing protocol
Comprehensive consideration of the various paths from the source network to the target network choose the route
OSPF, IS-IS
routers have a complete understanding of the entire network topology. It is a "route of sending a letter". A puts the information in a letter and sends it to B. B does not make any changes to it, copies it, and puts his information in another letter. The two letters are sent to C together. In this way, there is no change or loss of information, and finally all routers receive the same bunch of letters, and this bunch of letters is the LSDB. Then, each router uses the same SPF algorithm, takes itself as the root, calculates the SPF Tree (that is, each plan to reach the destination), selects the best path, and puts it in the routing table
The working principle of RIP routing protocol
RIP is a distance-vector routing protocol
Basic concepts of RIP
Regular update
Neighbor
Broadcast update
Full routing table update
RIP measurement value and update time
The RIP metric value is the number of hops. The
maximum number of hops is 15 hops, and 16 hops are unreachable.
RIP update time
Send routing update messages every 30s, UDP520 port
RIP routing update message
Send the entire routing table information
Split horizon
Performing split horizon can prevent the occurrence of routing loops. In the process of routing information transmission, the router learns routing information from an interface and no longer sends it out from this interface. At the same time, it can also reduce the link bandwidth resources occupied by routing update information.
Toxicity reversal
After the router receives the routing information of a certain network segment from a certain interface, it does not stop sending the information back, but sends it. It just marks this network segment as unreachable and sends it out. After receiving such routing information, the receiver router will immediately abandon the route instead of waiting for its aging time to expire. This can speed up routing convergence.
RIP routing protocol v1 and v2 2-1
The difference between RIPv1 and RIPv2
| RIP v1 | RIP v2 |
|---|---|
| Classful routing protocol | Classless routing protocol |
| Broadcast update (255.255.255.255) | Multicast update (224.0.0.9) |
| Does not support VLSM | Support VLSM |
| Automatic route summarization, cannot be turned off | Automatic summary can be closed, can be manually summarized |
| Discontinuous subnets are not supported | Support for discontinuous subnets |
Actual operation
[R1]rip 1-----Start RIP
[R1-rip-1]version 2-----Start version 2 (default is version 1)
[Rl-rip-1]undo summary----- Turn off automatic route aggregation (that is, all routing information will be classified according to IP addresses)
[R1-rip-1]network 192.168.10.0-----Announce the main network number, v2 will carry the mask multicast update 224.0.0.9, V1 does not carry the mask broadcast update 255.255.255.255
[R1-rip-1] network 200.1.1.0