Route Protocol troubleshooting

1RIPSummary

RIPRouting Information Protocol) Is based onD-VThe internal dynamic routing protocol of the algorithm. It is the first standard supported by all major vendors.IPThe routing protocol has become one of the criteria for transmitting router and Host Routing information. It is applicable to most campus networks and continuous regional networks with little change in usage rate. Generally, it should not be used in more complex environments.RIP.

 

RIP1As the distance vector routing protocolD-VAll algorithm-related restrictions, such as slow convergence and high bandwidth usage for Route loops and broadcast updates;RIP1As a classless routing protocol, update messages do not carry subnet masks, which means they are automatically aggregated on the main network boundary and do not supportVLSMAndCIDR; Similarly,RIP1As an old protocol, authentication is not provided, which may lead to potential risks. In short, simplicity isRIP1One of the reasons for widespread use, but some problems brought about by simplicity are alsoRIPImportant in troubleshooting.

 

RIPIn the process of continuous development and improvement, another version emerged:RIP2. AndRIP1The biggest difference is thatRIP2A classless routing protocol that carries a subnet mask in the update message. It supportsVLSM,CIDR, Authentication and multicast. These two versions are currently widely used, and the difference between the two causes problems inRIPPay special attention to troubleshooting.

 

We will also pay attentionRIPConfiguration and connectivity with other vendors.

 

2 RIP Configuration FAQs   2.1 The two configured routers are unavailable.RIP Interconnection

If the two configured routers are unavailableRIPWhen there is no problem with the physical connection, consider the following reasons::

 

(1) InQuidwayConnection between series routers:

LIt may beRIPNot started,Or the corresponding CIDR block is not enabled.

Note that you are usingNetworkConfigure the CIDR block according to the address category when running the command. For example, interface address137.11.1.1, Because137.11.1.1YesBClass address, if you set"Network 137.0. 0.0" The packets are not accepted by the peer end."Network 137.11. 0.0" You can receive the message correctly.

LAnother possible cause is thatRIP.

Check the configuration information to see if the interface has been setUndo rip work OrUndo rip inputOrUndo rip outpuTCommand.

L Another reason may be that the subnet mask does not match.

InRIP1In this classless routing protocol, each vro and host in the master network should have the same subnet mask. If the subnet mask length does not match, the information package cannot be correctly routed.

 

2.2 InQuidway Series routers cannot communicate with other manufacturers' Routers:

L Please take a photo first1).

L Then consider whether the version settings are different.QuidwayBy default,RIPYesRIP1AndRIP2Broadcast packets, but can only be sentRIP1Packets. IfQuidwayWhen series routers are interconnected,One configuration isRIP1,One configuration isRIP2,It can send and receive packets correctly. However, ifQuidwayWhen series routers are connected with vrouters of other manufacturers,QuidwaySeries routers are configuredRIP2And other manufacturers' RoutersRIP1,There may be problems.

 

2.3 RIP1 AndRIP2Problems caused by the difference

BecauseRIP2PairRIP1There are many functional extensions, and confusion between them will also lead to some problems.

 

(1) With verification, it does not work:

BecauseRIP-1Verification is not supported.RIPAfter configuration verification, it is actually not effective in the default ConditionRIP-1), Only the interfaces at both ends are configuredRip version 2Then the verification will take effect.

 

(2) The subnet mask is not matched.

If automatic aggregation is canceledBClass address routing, but24Bit mask.16Bit mask, for example:

137.11.1.0/24,Get137.11.0.0/16,Because there is no ConfigurationIp rip version 2,BecauseRIP-1The subnet mask is not supported. You can only combine routes by address type,137.11.1.0YesBThe Class address is aggregated137.11.0.0Outbound, RIP2Subnet Mask supported,In this way, the configured subnet mask can pass.

There are also two routes in the same master network, such 10.1.0 . 0And10.110.0.0, InRIP1All the differences are aggregated10.0.0.0Outgoing sending.RIP-2Configuration below16Bit masks can be differentiated.

 

(3) Problems caused by automatic aggregation

RIP1Always use aggregation, andRIPThe aggregation is performed by class,RIP2Aggregation is also used by default, but can be canceled in Protocol mode. Note the following two points:

 

LCancel auto aggregate onlyRIP2Valid Interface.

L Automatic aggregation is used to reduce the number of routes in the network. If there is no special reason, do not cancel it.

 

2.4 RIP Performance problems   1. OnlyHopAsMetricProblems

RIPOnly the number of hops is used as the metric value for route selection. The effect of bandwidth on different routes is not considered at all. In some cases, we will find that the route through which the packets arrive at the destination is not the best route. For example, a message from the source to the destination mayHopIs1OfISDNThe real function of this link is to back up and forward data without going through the bandwidth10 MbpsOnly because of itsHopThe value is2.

The solution is to re-design the network or use other routing protocols with greater flexibility, such:OSPF).

 

2. Broadcast update Problems

RIPThe default value is every30Second to broadcast and exchange the entire route table information, which will consume a lot of network bandwidth, especially in the WAN environment, may have serious performance problems.

WhenRIPWhen broadcast causes network performance problems, you can consider using"Neighbor"Command configurationRIPFixed-point transmission of packets. On the one hand, fixed-point transmission can be used in non-broadcast networks such as frame relay networks) SupportRIP. On the other hand, using fixed-point transmission in an Ethernet environment can significantly reduce network traffic.

 

3. Slow convergence

RIPIs a distance vector protocol.GarbageThe following interesting phenomenon may occur when the timer is set: Sometimes a command is configured but it does not work.,This may make us think that configuration errors or other faults are causedRIPThe reason for slow convergence requires a delay. Don't worry. wait a few minutes. Maybe you can see everything is normal if you have not done anything.

Note:

GarbageTime: When a route is marked as invalid, the router does not immediately delete the route, but maintains the route for a period of time, the router actually deletes the route from the routing table. This period of time is calledGarbageTime.GarbageTime helps increase the stability of the network, but the price is that the time for re-available routing is postponed, that is, convergence is slower.

 

2.5 Other related questions   1. Horizontal Split in Frame Relay:  

In frame relay,X25And so onNBMAWhen running on the network, you need to cancel horizontal segmentation and configure it in interface mode.No ip rip splitIf horizontal segmentation is used, the routing information cannot be exchanged between logical interfaces under the same physical interface.

 

2. Verification question:  

When verification is configured, the verification type is configured, and no verification information is displayed when no verification word is configured. verification does not take effect at this time.

 

3. Address borrow problem:  

Address borrow must be borrowed from both ends at the same time. If only one end is borrowed, the two ends are not connected because they are not in the same network segment. If both ends are borrowed, you can cancel the source address check.

 

4.2.6 RIP Troubleshooting steps  

Network-based measurementIPThe most common method for connectivity isPingCommand. Send from source to targetPingIf the command is successful, all physical layer, data link layer, and network layer functions are running properly. WhenIPConnectivity fails. First, we need to check whether all physical connections between the source and target are normal, and whether all interfaces and line protocols are running. When the physical layer and data link layer check are correct, we will focus on the network layer, assuming that the routing protocol for this network isRIPThe general troubleshooting steps are as follows:

 

1. Check the route tables of all route devices from the source to the destination to check whether route table items are lost.

Example: Source DevicePingTarget Device161.7.9.10No response, we should useDisplay ip routing-tableCommand to check that all route entries from the source to the destination are161.7.x.xX. xBased onRIPDifferent versions may vary.

 

2. When route table items are lost or other problems occur, check the network device'sRIPBasic Configuration (1) UseDisplay ripCommand ViewRIPParameters.

LViewRIPWhether it has been started, whether the related interfaces have been enabled,NetworkCommand settingsIs the network segment correct;

(2) UseDebug ripCommand SeriesRIPDebugging information.

PassDebugThe information can be clearly understood.RIPWhether the message is correctly sent and received.DebugThe information shows why the message fails to be sent or received.

 

3. WhenRIPNo problems are found in the basic configuration. Check the following items.

Whether to configure on the InterfaceUndo rip workCommand, whether there is a problem with the verification, whether there is a problem with the introduction of other routes, whether the access control list is configured incorrectly, and so on.

LViewDisplay current-configurationInformation can be seenRIPWhether the configuration information in interface mode is correct. If this interface is used for sending and receivingRIPThe interface configuration verifies the packet type and the type of authentication. The packet sent from the interface isRIP-1OrRIP-2Whether it is broadcast sending or multicast sending. Does the interface add additional routing permissions when receiving and sending routes.

L ViewDisplay current-configurationInformation can be seenRIPWhether the configuration information in Protocol mode is correct. For example, whether to introduce routes of other protocols. If so, how many route weights have been introduced; Whether to filter routes and what rules are used for filtering.