Article directory
- CCNP1: RIP – Routing Information Protocol (interference routing, V1, V2 compatibility issues, V1 continuous subnet issues)
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- 1. Explanation of RIP protocol:
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- 1. The difference between V1 and V2:
- 3. The working principle of RIP:
- 4. The breaking mechanism of RIP:
- 5. What happens if RIP does not have a breaking mechanism?
- Second, the configuration of RIP:
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- 1. Basic configuration:
- 2. Extended configuration:
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- (6) Interference routing:
- (7) Compatibility issues of V1 and V2:
- (8) The continuous subnet problem of V1:
CCNP1: RIP – Routing Information Protocol (interference routing, V1, V2 compatibility issues, V1 continuous subnet issues)
RIP: Routing Information Protocol, distance vector protocol, using hop count as a measure, working based on UDP520 port, management distance 120. Use cycle (30s) and trigger update
Trigger update: Used for timely re-convergence when the structure changes suddenly, telling all routers that a network segment has changed.
Periodic update: It is used to keep alive, ensure data receipt, and solve the situation that no confirmation package is received, but it occupies bandwidth.
1. Explanation of RIP protocol:
Three versions of RIP exist:
Work based on IPv4: V1, V2
Working on IPv6: NG version
The difference between 1, V1 and V2:
| Features\Version | V1 | V2 |
|---|---|---|
| Category | Category | No category (with mask) |
| Support | Support Continuity subnet | supports VLSM, only supports CIDR, does not support supernet |
| update method | broadcast update 255.255.255.255 |
multicast update 224.0.0.9 |
| Does authentication support | No | Yes |
| Timer | Notes |
|---|---|
| 180s failure | If you don’t receive an update once and you can’t judge the route, it’s gone. It may be because of the network card, so you gave 6 chances. Once the 6 opportunities are used up, it is determined that this route is invalid. Immediately afterwards, another poisonous route will be sent to other neighbors to inform other neighbors that the path is no longer reachable. |
| 180s suppression | Normally does not work, under normal circumstances assume R1 reaches R2, jump The number is 1 hop. However, the number of hops suddenly increases without warning, indicating that the network has gone out of the loop. At this time, after suppressing for 180s, it converges again to find a new network segment. |
| 240s refresh | That is, it will delete the routing entries that do not exist |
Appropriately modifying the timer can speed up the convergence speed of the device. It is recommended to maintain the original multiple relationship when modifying, and it is not easy to modify too small, otherwise bandwidth resources will be occupied, and all devices on the entire network need to be modified.
R1(config)#router rip R1(config-router)#timers basic 15 90 90 120 </code>
The above is the content copied and pasted from my CCNA classification, if you want to view it, please click here: CCNA3: Dynamic Routing Protocol, RIP – Routing Information Protocol and the next 3 extended configurations , is the extended configuration that CCNP needs to supplement compared to CCNA:
(6) Interference routing:
Because RIP uses the hop count as a measure, the route selection may be inaccurate during route selection, as shown in the following figure:
The above road has a large number of hops, but the bandwidth is good. The router has chosen the following path, which requires us to intervene in the path selection.
Interference principle: use the offset list strategy to achieve: on the inbound or outbound interface of the control plane traffic, increase the metric value in the traffic, and then affect the route selection. When adding metrics, if multiple devices are set, the metrics will be superimposed.
Defect of the offset list: it can only be increased, not decreased. If you want to modify one of the paths, you need to increase the measurement on the other path
The control plane is the direction of transmitting the routing table (R4 sends its loopback to R1), the direction of the data plane access target (R1pingR4) .
| Level | Annotation |
|---|---|
| Control Level | For the routing protocol, the router learns the route through the IGP protocol to form a routing table, which is |
| data level | For sending data, the control plane builds a routing table to provide services for sending data at the data plane, that is, without the control plane forming a routing table, the data plane has no meaning. |
The configuration is as follows:
R1(config)#access-list 1 permit 3.3.3.0 (first use ACL to capture the corresponding network number traffic: equivalent to 3.3.3.0 0.0.0.0) R1(config)#router rip (set in rip again) R1(config-router)#offset-list 1 in 2 serial 1/1
offset: list of offsets
1: ACL number
2: The measurement is increased by 2 on the basis of the original
in: The direction of calling the interface is inbound
serial 1/1: incoming interface
(7) Compatibility issues of V1 and V2:
Here we want to set up an experimental environment, the underlying configuration is shown in the figure below, and then R1 runs RIPv1 version, R2 runs RIPv1 + version, and R3 runs V2 version.
The declaration is as follows:
R1(config)#router rip R1(config-router)#version 1 R1(config-router)#network 1.0.0.0 R1(config-router)#network 12.0.0.0 R2(config)#router rip R2(config-router)#network 12.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 23.0.0.0 R3(config)#router rip R3(config-router)#version 2 R3(config-router)#no auto-summary R3(config-router)#network 23.0.0.0 R3(config-router)#network 3.0.0.0 </code>
Their routing tables after the announcement are as follows:
We found that only the routing table of R3 is faulty, and the previous routes of R1 and R2 were not received.
Let’s take a look at their protocol operation again:
R1 only sends and receives version 1
V1 + version: release V1, both V1 and V2 accept V2
| Receiver relationship\version | Standard V1 | Upgrade V1 |
|---|---|---|
| Send | V1 | V1 |
| Receive | V1 | V1, V2 |
No matter what version the device is currently using, the version information that can be sent and received by all interfaces can be modified, so the compatibility problem can be solved:
①V1, V1 + devices can imitate the routing of sending and receiving V2, but they cannot carry the mask.
②V2 can normally issue the same route as V1.
R2(config)#int s0/1 R2(config-if)#ip rip send version 1 2 R2(config-if)#ip rip receive version 1 2 </code>
(8) The continuous subnet problem of V1:
Continuity subnet: Same parent network, same mask length (Only contiguous subnets can be aggregated).
For example, the following four network segments are a continuous subnet.
Let’s take the following figure as an example. When the two routers are running the V1 version of RIP, R1 will not learn the network segment on 1.1.2.0, and R2 will not learn the network segment on R1.
The underlying configuration is shown in the figure above, and the declaration is as follows:
R1(config)#router rip R1(config-router)#version 1 R1(config-router)#network 1.0.0.0 R1(config-router)#network 12.0.0.0 R2(config)#router rip R2(config-router)#version 1 R2(config-router)#network 1.0.0.0 R2(config-router)#network 12.0.0.0 </code>
We checked their routing tables and found that they did not learn the loopback network segment of the other party.
The reasons are as follows:
From the announcement above, we should also be able to see that the network segment of 1.0.0.0 was announced. When two routers receive the route from the peer, It is found that, as announced by myself, according to the split horizon rule of RIP, the same route is no longer received, which leads to the fact that the network segment is not fully learned.
Solution principle:
In V1 RIP, if the local is going to share the routing of the neighbor with the directly connected network segment of the local and the neighbor If it is a continuous subnet, the local will send the route with the host bit to the neighbor. When the neighbor receives the route with the host bit, it will use the mask of the network segment directly connected to the neighbor to add to these routes.
solution:
According to the solution principle, we can add a second address to the IP between R1 and R2 (or directly cover the original IP), so that it can be connected with R1 and R2 The loopback constructs the continuity subnet, so that the three network segments are all in the same continuity subnet.
The configuration is as follows:
R1(config)#int s0/0 R1(config-if)#ip add 1.1.3.1 255.255.255.0 secondary R2(config)#int s0/0 R2(config-if)#ip add 1.1.3.2 255.255.255.0 secondary </code>
Finally, the routing table is complete:
