RIP is a simple Interior Gateway Protocol (IGP), mainly used in small-sized networks, such as academic networks and simple LANs. It is not applicable to complex networks.

RIP is widely used in practical networking because it is easy to implement, configure, and maintain.

RIP working mechanism

Introduction

RIP is a distance vector routing protocol, using UDP packets for exchanging information through port 520.

RIP uses a hop count to measure the distance to a destination. The hop count from a router to a directly connected network is 0. The hop count from a router to a directly connected router is 1. To limit convergence time, the RIP metric value ranges from 0 to 15. A metric value of 16 (or greater) is considered infinite, which means the destination network is unreachable. Because of this, RIP is not suitable for large-sized networks.

RIP prevents routing loops by implementing the split horizon and poison reverse functions.

RIP routing table

A RIP router has a routing table containing routing entries of all reachable destinations, and each routing entry contains the following elements:

· Destination address—IP address of a host or a network.

· Next hop—IP address of the adjacent router’s interface to reach the destination.

· Egress interface—Packet outgoing interface.

· Metric—Cost from the local router to the destination.

· Route time—Time elapsed since the routing entry was last updated. The time is reset to 0 every time the routing entry is updated.

· Route tag—Identifies a route, used in a routing policy to flexibly control routes. For more information about routing policy, see the chapter “Configuring routing policies.”

RIP timers

RIP employs the following timers:

· Update timer—Defines the interval between routing updates.

· Timeout timer—Defines the route aging time. If no update for a route is received within the aging time, the metric of the route is set to 16 in the routing table.

· Suppress timer—Defines how long a RIP route stays in suppressed state. When the metric of a route is 16, the route enters the suppressed state. In suppressed state, only routes which come from the same neighbor and whose metric is less than 16 will be received by the router to replace unreachable routes.

· Garbage-collect timer—Defines the interval from when the metric of a route becomes 16 to when it is deleted from the routing table. During the garbage-collect timer length, RIP advertises the route with the routing metric set to 16. If no update is announced for that route after the garbage-collect timer expires, the route will be deleted from the routing table.

Routing loops prevention

RIP is a distance vector (D-V) routing protocol. Since a RIP router advertises its own routing table to neighbors, routing loops may occur.

RIP uses the following mechanisms to prevent routing loops:

· Counting to infinity—The metric value of 16 is defined as unreachable. When a routing loop occurs, the metric value of the route will increment to 16.

· Split horizon—A router does not send the routing information learned from a neighbor to the neighbor to prevent routing loops and save bandwidth.

· Poison reverse—A router sets the metric of routes received from a neighbor to 16 and sends back these routes to the neighbor to help delete such information from the neighbor’s routing table.

· Triggered updates—A router advertises updates once the metric of a route is changed rather than after the update period expires to speed up network convergence.

RIP operation

The following procedure describes how RIP works.

1. After RIP is enabled, the router sends request messages to neighboring routers. Neighboring routers return Response messages including information about their routing tables.

2. After the router receives this information, it updates its local routing table, and sends triggered update messages to its neighbors. All routers on the network do this to keep the latest routing information.

3. By default, a RIP router sends its routing table to neighbors every 30 seconds.

4. RIP ages out routes by adopting an aging mechanism to keep only valid routes.

RIP versions

RIP has the following versions: RIPv1 and RIPv2.

RIPv1 is a classful routing protocol and supports message advertisement via broadcast only. RIPv1 protocol messages do not carry mask information, which means it can only recognize routing information of natural networks such as Class A, B, and C. That is why RIPv1 does not support discontiguous subnets.

RIPv2 is a classless routing protocol, and has the following advantages over RIPv1:

· Supports route tags. Route tags are used in routing policies to flexibly control routes.

· Supports masks, route summarization and Classless Inter-Domain Routing (CIDR).

· Supports designated next hops to select the best ones on broadcast networks.

· Supports multicasting routing updates to reduce resource consumption. Only RIPv2 routers can receive these update messages.

· Supports plain text authentication and MD5 authentication to enhance security.

NOTE:

RIPv2 has two types of message transmission: broadcast and multicast. Multicast is the default type using 224.0.0.9 as the multicast address. The interface working in the RIPv2 broadcast mode can also receive RIPv1 messages.

RIP message format

A RIP message consists of a header and up to 25 route entries. (A RIPv2 authentication message uses the first route entry as the authentication entry, leaving 24 available.)

RIPv1 message format

Figure 1 RIPv1 Message Format

Header description:

· Command—Type of message. 1 indicates request, which is used to request all or part of the routing information from the neighbor; 2 indicates response, which contains all or part of the routing information. A response message consists of up to 25 route entries.

· Version—Version of RIP, 0x01 for RIPv1.

· Must be zero—This field must be zero.

· AFI—Address Family Identifier, 2 for IP.

· IP Address—Destination IP address of the route. It can be a natural network, subnet or a host address.

· Metric—Cost of the route.

RIPv2 message format

The format of RIPv2 message is similar to RIPv1.

Figure 2 RIPv2 Message Format

Differences from RIPv1:

· Version–Version of RIP. For RIPv2 the value is 0x02.

· Route tag.

· IP address—Destination IP address. It can be a natural network address, subnet address or host address.

· Subnet mask—Mask of the destination address.

· Next hop—If set to 0.0.0.0, it indicates that the originator of the route is the best next hop. Otherwise, it indicates a next hop better than the originator of the route.

RIPv2 authentication message format

RIPv2 sets the AFI field of the first route entry to 0xFFFF to identify authentication information.

Figure 3 RIPv2 Authentication Message

· Authentication Type—A value of 2 represents plain text authentication; a value of 3 represents MD5.

· Authentication—Authentication data, including password information when plain text authentication is adopted or including key ID, MD5 authentication data length and sequence number when MD5 authentication is adopted.

NOTE:

· RFC 1723 only defines plain text authentication. For more information about MD5 authentication, see RFC 2453, RIP Version 2.

· With RIPv1, you can configure the authentication mode in interface view. However, the configuration will not take effect because RIPv1 does not support authentication.

TRIP

Triggered RIP (TRIP), a RIP extension for WANs, is mainly used in dial-up networks.

Working mechanism

Routing information is sent in triggered updates rather than in periodic broadcasts to reduce route management cost on WANs.

· A routing update message is sent when data in the routing table changes or the next hop is unreachable.

· Since the periodic update delivery is canceled, an acknowledgement and retransmission mechanism is required to guarantee successful updates transmission on WANs.

Message types

RIP uses the following new types of message which are identified by the value of the command field.

· Update request (Type-9)—Requests the needed routes from the neighbor.

· Update response (Type-10)—Contains the routes requested by the neighbor.

· Update Acknowledge (Type-11)—Acknowledges received update responses.

TRIP retransmission mechanism

· If a router receives no update responses within a specified interval after sending an update request, it sends the request again. If the router still receives no update response after the upper limit for sending requests is reached, it considers the neighbor unreachable.

· If a router receives no update acknowledge within a specified interval after sending an update response, it sends the update response again. If the router still receives no update acknowledge after the upper limit for sending update responses is reached, it considers the neighbor unreachable.

Supported RIP features

The current implementation supports the following RIP features:

· RIPv1 and RIPv2.

· RIP support for multi-VPN-instance.

RIP can serve as the IGP running between CE and PE on an MPLS L3VPN network. For related information, see MPLS Configuration Guide.

· TRIP

· RIP FRR

· BFD

RIP periodically sends route update requests to neighbors. If no route update response for a route is received within the specified interval, RIP considers the route unreachable. This mechanism cannot detect link faults quickly. After BFD is configured for RIP, and BFD detects a broken link, RIP can quickly age out the unreachable route, thus avoiding interference to other services.

Protocols and standards

· RFC 1058, Routing Information Protocol

· RFC 1723, RIP Version 2 - Carrying Additional Information

· RFC 1721, RIP Version 2 Protocol Analysis

· RFC 1722, RIP Version 2 Protocol Applicability Statement

· RFC 1724, RIP Version 2 MIB Extension

· RFC 2082, RIPv2 MD5 Authentication

· RFC 2091, Triggered Extensions to RIP to Support Demand Circuits

· RFC 2453, RIP Version 2

RIP configuration task list

Complete the following tasks to configure RIP:

Task		Remarks
Configuring RIP basic functions		Required
Configuring RIP route control	Configuring an additional routing metric	Optional
	Configuring RIPv2 route summarization	Optional
	Disabling host route reception	Optional
	Advertising a default route	Optional
	Configuring inbound/outbound route filtering	Optional
	Configuring a priority for RIP	Optional
	Configuring RIP route redistribution	Optional
Tuning and optimizing RIP networks	Configuring RIP timers	Optional
	Configuring split horizon and poison reverse	Optional
	Configuring the maximum number of load balanced routes	Optional
	Enabling zero field check on incoming RIPv1 messages	Optional
	Enabling source IP address check on incoming RIP updates	Optional
	Configuring RIPv2 message authentication	Optional
	Specifying a RIP neighbor	Optional
	Configuring TRIP	Optional
	Configuring RIP-to-MIB binding	Optional
	Configuring the RIP packet sending rate	Optional
Configuring RIP FRR		Optional
Configuring BFD for RIP	Single-hop detection in BFD echo packet mode	Optional
Configuring BFD for RIP	Bidirectional detection in BFD control packet mode	Optional

Configuring RIP basic functions

Configuration prerequisites

Before you configure RIP basic functions, complete the following tasks:

· Configure the link layer protocol.

· Configure IP addresses for interfaces, and make sure that all neighboring routers are reachable to each other.

Configuration procedure

Enabling RIP and a RIP interface

To enable RIP:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable a RIP process and enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	Disabled by default
3. Enable RIP on the interface attached to the specified network.	network network-address	Disabled by default

NOTE:

· If you make some RIP configurations in interface view before enabling RIP, those configurations will take effect after RIP is enabled.

· RIP runs only on the interfaces residing on the specified networks. Specify the network after enabling RIP to validate RIP on a specific interface.

· You can enable RIP on all interfaces using the command network 0.0.0.0.

· If a physical interface is attached to multiple networks, you cannot advertise these networks in different RIP processes.

Configuring the interface behavior

To configure the interface behavior:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Disable an or all interfaces from sending routing updates (the interfaces can still receive updates).	silent-interface { interface-type interface-number \| all }	Optional. All interfaces can send routing updates by default.
4. Return to system view.	quit	N/A
5. Enter interface view.	interface interface-type interface-number	N/A
6. Enable the interface to receive RIP messages.	rip input	Optional. Enabled by default.
7. Enable the interface to send RIP messages.	rip output	Optional. Enabled by default.

Configuring a RIP version

You can configure a RIP version in RIP or interface view.

· If neither global nor interface RIP version is configured, the interface sends RIPv1 broadcasts and can receive the following packets: RIPv1 broadcast, RIPv1 unicast, RIPv2 broadcast, RIPv2 multicast, and RIPv2 unicast.

· If an interface has no RIP version configured, it uses the global RIP version; otherwise it uses the RIP version configured on it.

· With RIPv1 configured, an interface sends RIPv1 broadcasts, and can receive RIPv1 broadcasts and RIPv1 unicasts.

· With RIPv2 configured, a multicast interface sends RIPv2 multicasts and can receive RIPv2 unicasts, broadcasts, and multicasts.

· With RIPv2 configured, a broadcast interface sends RIPv2 broadcasts and can receive RIPv1 unicasts, and broadcasts, and RIPv2 broadcasts, multicasts, and unicasts.

To configure a RIP version:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Specify a global RIP version.	version { 1 \| 2 }	Optional. By default, if an interface has a RIP version specified, the version takes precedence over the global one. If no RIP version is specified for an interface, the interface can send RIPv1 broadcasts, and receive RIPv1 broadcasts, unicasts, RIPv2 broadcasts, multicasts and unicasts.
4. Return to system view.	quit	N/A
5. Enter interface view.	interface interface-type interface-number	N/A
6. Specify a RIP version for the interface.	rip version { 1 \| 2 [ broadcast \| multicast ] }	Optional. By default, if an interface has no RIP version specified, the global version takes effect. If no global RIP version is specified, the interface can send RIPv1 broadcasts, and receive RIPv1 broadcasts, unicasts, RIPv2 broadcasts, multicasts and unicasts.

Configuring RIP route control

In complex networks, you must configure advanced RIP features.

Before you configure RIP routing feature, complete the following tasks:

· Configure IP addresses for interfaces, and make sure that all neighboring routers can communicate with each other.

· Configure RIP basic functions.

Configuring an additional routing metric

An additional routing metric (hop count) can be added to the metric of an inbound or outbound RIP route.

The outbound additional metric is added to the metric of a sent route, and the route’s metric in the routing table is not changed.

The inbound additional metric is added to the metric of a received route before the route is added into the routing table, and the route’s metric is changed. If the sum of the additional metric and the original metric is greater than 16, the metric of the route will be 16.

To configure additional routing metrics:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Define an inbound additional routing metric.	rip metricin [ route-policy route-policy-name ] value	Optional 0 by default
4. Define an outbound additional routing metric.	rip metricout [ route-policy route-policy-name ] value	Optional 1 by default

Configuring RIPv2 route summarization

Route summarization means that subnets in a natural network are summarized into a natural network that is sent to other networks. This feature can reduce the size of routing tables.

After route summarization, the smallest metric among all the summarized routes is used as the metric of the summary route.

Enabling RIPv2 route automatic summarization

You can disable RIPv2 route automatic summarization if you want to advertise all subnet routes.

To enable RIPv2 route automatic summarization:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable RIPv2 automatic route summarization.	summary	Optional. Enabled by default. If the subnet routes in the routing table are not consecutive, disable automatic route summarization to avoid black hole routing.

Advertising a summary route

To configure RIPv2 to advertise a summary route on the specified interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Disable RIPv2 automatic route summarization.	undo summary	Enabled by default
4. Return to system view.	quit	N/A
5. Enter interface view.	interface interface-type interface-number	N/A
6. Advertise a summary route.	rip summary-address ip-address { mask \| mask-length }	N/A

NOTE:

You must disable RIPv2 route automatic summarization before advertising a summary route on an interface.

Disabling host route reception

Sometimes a router may receive from the same network many host routes, which are not helpful for routing and consume a large amount of network resources. You can disable RIP from receiving host routes to save network resources.

To disable RIP from receiving host routes:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Disable RIP from receiving host routes.	undo host-route	Enabled by default

NOTE:

RIPv2 can be disabled from receiving host routes, but RIPv1 cannot.

Advertising a default route

You can configure RIP to advertise a default route with a specified metric to RIP neighbors.

· In RIP view, you can configure all the interfaces of the RIP process to advertise a default route; in interface view, you can configure a RIP interface of the RIP process to advertise a default route. The interface view takes precedence over on the interface.

· If a RIP process is enabled to advertise a default route, to disable an interface of the RIP process from default route advertisement, you can use the rip default-route no-originate command on the interface.

To configure RIP to advertise a default route:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable RIP to advertise a default route.	default-route { only \| originate } [ cost cost ]	Not enabled by default.
4. Return to system view.	quit	N/A
5. Enter interface view.	interface interface-type interface-number	N/A
6. Configure the RIP interface to advertise a default route.	rip default-route { { only \| originate } [ cost cost ] \| no-originate }	Optional. By default, a RIP interface can advertise a default route if the RIP process is configured with default route advertisement.

NOTE:

The router enabled to advertise a default route does not receive default routes from RIP neighbors.

Configuring inbound/outbound route filtering

The router supports route filtering. You can filter routes by configuring the inbound and outbound route filtering policies by referencing an ACL or IP prefix list. You can also configure the router to receive only routes from a specified neighbor.

To configure route filtering:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the filtering of incoming routes.	filter-policy { acl-number \| gateway ip-prefix-name \| ip-prefix ip-prefix-name [ gateway ip-prefix-name ] } import [ interface-type interface-number ]	Not configured by default
4. Configure the filtering of outgoing routes.	filter-policy { acl-number \| ip-prefix ip-prefix-name } export [ protocol [ process-id ] \| interface-type interface-number ]	Not configured by default

NOTE:

· Using the filter-policy import command filters incoming routes. Routes not passing the filtering will be neither installed into the routing table nor advertised to neighbors.

· Using the filter-policy export command filters outgoing routes, including routes redistributed with the import-route command.

Configuring a priority for RIP

Multiple IGP protocols may run in a router. If you want RIP routes to have a higher priority than those learned by other routing protocols, assign RIP a smaller priority value to influence optimal route selection.

To configure a priority for RIP:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure a priority for RIP.	preference [ route-policy route-policy-name ] value	Optional 100 by default

Configuring RIP route redistribution

If a router runs RIP and other routing protocols, you can configure RIP to redistribute OSPF, IS-IS, BGP, static, or direct routes.

To configure RIP route redistribution:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure a default metric for redistributed routes.	default cost value	Optional. The default metric of a redistributed route is 0.
4. Redistribute routes from another protocol.	import-route protocol [ process-id \| all-processes \| allow-ibgp ] [ cost cost \| route-policy route-policy-name \| tag tag ] *	By default, no redistribution is configured.

NOTE:

Only active routes can be redistributed. Use the display ip routing-table protocol command to display route state information.

Tuning and optimizing RIP networks

Complete the following tasks before tuning and optimizing RIP networks:

· Configure network addresses for interfaces, and make neighboring nodes reachable to each other.

· Configure RIP basic functions.

Configuring RIP timers

You can change the RIP network convergence speed by adjusting RIP timers.

To configure RIP timers:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure values for RIP timers.	timers { garbage-collect garbage-collect-value \| suppress suppress-value \| timeout timeout-value \| update update-value } *	Optional. The default update timer, timeout timer, suppress timer, and garbage-collect timer are 30s, 180s, 120s and 120s respectively.

NOTE:

Based on network performance, make RIP timers of RIP routers identical to each other to avoid unnecessary traffic or route oscillation.

Configuring split horizon and poison reverse

NOTE:

If both split horizon and poison reverse are configured, only the poison reverse function takes effect.

The split horizon and poison reverse functions can avoid routing loops.

Enabling split horizon

The split horizon function disables an interface from sending routes received from the interface to prevent routing loops between adjacent routers.

To enable split horizon:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable split horizon.	rip split-horizon	Optional Enabled by default

NOTE:

Disabling the split horizon function on a point-to-point link does not take effect.

Enabling poison reverse

The poison reverse function allows an interface to advertise the routes received from it, but the metric of these routes is set to 16, making them unreachable. This can avoid routing loops between neighbors.

To enable poison reverse:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter interface view.	interface interface-type interface-number	N/A
3. Enable poison reverse.	rip poison-reverse	Disabled by default

Configuring the maximum number of load balanced routes

This task allows you to implement load balancing over multiple equal-cost RIP routes.

To configure the maximum number of load balanced routes:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the maximum number of load balanced routes.	maximum load-balancing number	Optional

Enabling zero field check on incoming RIPv1 messages

Some fields in the RIPv1 message must be zero. These fields are called “zero fields”. You can enable zero field check on received RIPv1 messages. If such a field contains a non-zero value, the RIPv1 message will not be processed. If you are sure that all messages are trusty, disable zero field check to save CPU resources.

This feature does not apply to RIPv2 packets that have no zero fields.

To enable zero field check on incoming RIPv1 messages:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable zero field check on received RIPv1 messages.	checkzero	Optional Enabled by default

Enabling source IP address check on incoming RIP updates

You can enable source IP address check on incoming RIP updates.

For a message received on an Ethernet interface, RIP compares the source IP address of the message with the IP address of the interface. If they are not in the same network segment, RIP discards the message.

For a message received on a serial interface, RIP checks whether the source address of the message is the IP address of the peer interface. If not, RIP discards the message.

To enable source IP address check on incoming RIP updates:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Enable source IP address check on incoming RIP messages.	validate-source-address	Optional Enabled by default

NOTE:

The source IP address check feature should be disabled if the RIP neighbor is not directly connected.

Configuring RIPv2 message authentication

In a network requiring high security, you can configure this task to implement RIPv2 message validity check and authentication.

RIPv2 supports two authentication modes: plain text and MD5.

In plain text authentication, the authentication information is sent with the RIP message; however, this cannot meet high security needs.

To configure RIPv2 message authentication:

Step	Command
1. Enter system view.	system-view
2. Enter interface view.	interface interface-type interface-number
3. Configure RIPv2 authentication.	rip authentication-mode { md5 { rfc2082 key-string key-id \| rfc2453 key-string } \| simple password }

NOTE:

This feature does not apply to RIPv1 because RIPv1 does not support authentication. Although you can specify an authentication mode for RIPv1 in interface view, the configuration does not take effect.

Specifying a RIP neighbor

Usually, RIP sends messages to broadcast or multicast addresses. On non broadcast or multicast links, you must manually specify RIP neighbors.

To specify a RIP neighbor:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Specify a RIP neighbor.	peer ip-address	N/A
4. Disable source address check on incoming RIP updates.	undo validate-source-address	Not disabled by default

NOTE:

· You need not use the peer ip-address command when the neighbor is directly connected; otherwise the neighbor may receive both the unicast and multicast (or broadcast) of the same routing information.

· If a specified neighbor is not directly connected, disable source address check on incoming updates.

Configuring TRIP

In a connection oriented network, a router may establish connections to multiple remote routers. In a WAN, links are created and removed as needed. In such applications, a link created between two nodes for data transmission is temporary and infrequently.

TRIP should be enabled when it is necessary to exchange routing information through on-demand links or triggered RIP.

Enabling TRIP

To enable TRIP:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable RIP.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Return to system view.	quit	N/A
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable TRIP.	rip triggered	Disabled by default

NOTE:

If RIP is disabled, TRIP is also disabled.

Configuring TRIP retransmission parameters

You can specify the interval and count for retransmitting a request or response as needed.

For two routers on an analog dial-up link, the difference between retransmission intervals on the two ends must be greater than 50 seconds; otherwise, they cannot become TRIP neighbors.

To configure TRIP retransmission parameters:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable RIP and enter its view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the interval for retransmitting an update request or update response.	trip retransmit timer retransmit-time-value	5 seconds by default
4. Configure the maximum count for retransmitting an update request or update response.	trip retransmit count retransmit-count-value	Optional 36 by default

NOTE:

The maximum retransmission interval (count × interval) for a packet cannot be so long that the router still resends the packet when its neighbor is down.

Configuring RIP-to-MIB binding

This task allows you to enable a specific RIP process to receive SNMP requests.

To bind RIP to MIB:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Bind RIP to MIB.	rip mib-binding process-id	Optional. By default, MIB is bound to RIP process 1.

Step

Command

Remarks

1. Enter system view.

system-view

N/A

2. Bind RIP to MIB.

rip mib-binding process-id

Optional.

By default, MIB is bound to RIP process 1.

Configuring the RIP packet sending rate

RIP periodically sends routing information in RIP packets to RIP neighbors.

Sending large numbers of RIP packets at the same time may affect router performance and consume large network bandwidth. To solve this problem, you can specify the maximum number of RIP packets that can be sent at the specified interval.

To configure the RIP packet sending rate:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable a RIP process and enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the maximum number of RIP packets that can be sent at the specified interval.	output-delay time count count	Optional. By default, an interface sends up to three RIP packets every 20 milliseconds.

Configuring RIP FRR

NOTE:

· RIP FRR is only effective for non-recursive RIP routes (that are learned from directly connected neighbors).

· Do not use RIP FRR and BFD (for RIP) at the same time; otherwise, RIP FRR may fail to take effect.

When a link in a RIP network fails, the traffic is interrupted until RIP completes routing convergence based on the new network topology.

You can enable RIP fast reroute (FRR) to reduce traffic recovery time.

Figure 4 Network diagram for RIP FRR

In Figure 4, after you enable FRR on Router B, RIP designates a backup next hop using a routing policy when a network failure is detected. Packets are directed to the backup next hop to reduce traffic recovery time. At the same time, RIP calculates the shortest path based on the new network topology, and forwards packets over the path after network convergence.

Configuration prerequisites

You must specify a next hop by using the apply fast-reroute backup-interface command in a routing policy and reference the routing policy with RIP FRR. For more information about routing policy configuration, see the chapter “Configuring routing policies.”

Configuration procedure

To configure RIP FRR:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Configure the source address of echo packets.	bfd echo-source-ip ip-address	Not configured by default
3. Enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
4. Enable RIP FRR and reference a routing policy to designate a backup next hop.	fast-reroute route-policy route-policy-name	Disabled by default

Configuring BFD for RIP

NOTE:

For more information about BFD, see High Availability Configuration Guide.

BFD for RIP provides the following link detection modes:

· Single-hop detection in BFD echo packet mode for a directly connected neighbor. In this mode, a BFD session is established only when the neighbor has route information to send.

· Bidirectional detection in BFD control packet mode for an indirectly connected neighbor. In this mode, a BFD session is established only when both ends have routes to send and BFD is enabled on the receiving interface.

Single-hop detection in BFD echo packet mode

To configure BFD for RIP (single-hop detection in BFD echo packet mode):

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Configure the source IP address of BFD echo packets.	bfd echo-source-ip ip-address	By default, no source IP address is configured for BFD echo packets.
3. Enter interface view.	interface interface-type interface-number	N/A
4. Enable BFD on the RIP interface.	rip bfd enable	Disabled by default.

Bidirectional detection in BFD control packet mode

To configure BFD for RIP (bidirectional detection in BFD control packet mode):

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Create a RIP process and enter RIP view.	rip [ process-id ] [ vpn-instance vpn-instance-name ]	By default, RIP is disabled.
3. Specify a RIP neighbor.	peer ip-address	By default, RIP does not unicast updates to any peer.
4. Enter interface view.	interface interface-type interface-number	N/A
5. Enable BFD on the RIP interface.	rip bfd enable	Disabled by default.

NOTE:

· Unidirectional detection in BFD echo packet mode only works for RIP neighbors that are directly connected (one hop away from each other).

· Using the undo peer command does not remove the neighbor relationship at once; therefore, it cannot bring down the BFD session at once.

Displaying and maintaining RIP

Task	Command	Remarks
Display RIP current status and configuration information.	display rip [ process-id \| vpn-instance vpn-instance-name ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display all active routes in RIP database.	display rip process-id database [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display RIP interface information.	display rip process-id interface [ interface-type interface-number ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display routing information about a specified RIP process.	display rip process-id route [ ip-address { mask \| mask-length } \| peer ip-address \| statistics ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Reset a RIP process.	reset rip process-id process	Available in user view
Clear the statistics of a RIP process.	reset rip process-id statistics	Available in user view

RIP configuration examples

Configuring RIP version

Network requirements

As shown in Figure 5, enable RIPv2 on all interfaces on Router A and Router B.

Figure 5 Network diagram

Configuration procedure

1. Configure an IP address for each interface. (Details not shown)

2. Configure basic RIP functions:

# Configure Router A.

<RouterA> system-view

[RouterA] rip

[RouterA-rip-1] network 1.0.0.0

[RouterA-rip-1] network 2.0.0.0

[RouterA-rip-1] network 3.0.0.0

# Configure Router B.

<RouterB> system-view

[RouterB] rip

[RouterB-rip-1] network 1.0.0.0

[RouterB-rip-1] network 10.0.0.0

# Display the RIP routing table on Router A.

[RouterA] display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

Peer 1.1.1.2 on GigabitEthernet1/1/1

Destination/Mask Nexthop Cost Tag Flags Sec

10.0.0.0/8 1.1.1.2 1 0 RA 9

The output shows that RIPv1 uses natural mask to advertise routing information.

3. Configure a RIP version:

# Configure RIPv2 on Router A.

[RouterA] rip

[RouterA-rip-1] version 2

[RouterA-rip-1] undo summary

# Configure RIPv2 on Router B.

[RouterB] rip

[RouterB-rip-1] version 2

[RouterB-rip-1] undo summary

# Display the RIP routing table of Router A.

[RouterA] display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

Peer 1.1.1.2 on GigabitEthernet1/1/1

Destination/Mask Nexthop Cost Tag Flags Sec

10.0.0.0/8 1.1.1.2 1 0 RA 87

10.1.1.0/24 1.1.1.2 1 0 RA 19

10.2.1.0/24 1.1.1.2 1 0 RA 19

The output shows that RIPv2 uses classless subnet mask.

NOTE:

Because RIPv1 routing information has a long aging time, it will still exist before being aged out after RIPv2 is configured.

Configuring RIP route redistribution

Network requirements

As shown in the following figure:

· Two RIP processes are running on Router B, which communicates with Router A through RIP 100 and with Router C through RIP 200.

· Configure RIP 200 to redistribute direct routes and routes from RIP 100 on Router B. Router C can then learn routes destined for 10.2.1.0/24 and 11.1.1.0/24, and Router A cannot learn routes destined for 12.3.1.0/24 and 16.4.1.0/24.

· Configure a filtering policy on Router B to filter out the route 10.2.1.1/24 from RIP 100, making the route not advertised to Router C.

Figure 6 Network diagram

Configuration procedure

1. Configure an IP address for each interface. (Details not shown)

2. Configure RIP basic functions:

# Enable RIP 100, and configure a RIP version of 2 on Router A.

<RouterA> system-view

[RouterA] rip 100

[RouterA-rip-100] network 10.0.0.0

[RouterA-rip-100] network 11.0.0.0

[RouterA-rip-100] version 2

[RouterA-rip-100] undo summary

[RouterA-rip-100] quit

# Enable RIP 100 and RIP 200, configure RIP version as 2 on Router B.

<RouterB> system-view

[RouterB] rip 100

[RouterB-rip-100] network 11.0.0.0

[RouterB-rip-100] version 2

[RouterB-rip-100] undo summary

[RouterB-rip-100] quit

[RouterB] rip 200

[RouterB-rip-200] network 12.0.0.0

[RouterB-rip-200] version 2

[RouterB-rip-200] undo summary

[RouterB-rip-200] quit

# Enable RIP 200 and configure RIP version as 2 on Router C.

<RouterC> system-view

[RouterC] rip 200

[RouterC-rip-200] network 12.0.0.0

[RouterC-rip-200] network 16.0.0.0

[RouterC-rip-200] version 2

[RouterC-rip-200] undo summary

# Display the routing table of Router C.

[RouterC] display ip routing-table

Routing Tables: Public

Destinations : 6 Routes : 6

Destination/Mask Proto Pre Cost NextHop Interface

12.3.1.0/24 Direct 0 0 12.3.1.2 GE3/1/1

12.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

16.4.1.0/24 Direct 0 0 16.4.1.1 GE3/1/2

16.4.1.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

3. Configure RIP route redistribution:

# Configure RIP 200 to redistribute direct routes and routes from RIP 100 on Router B.

[RouterB] rip 200

[RouterB-rip-200] import-route rip 100

[RouterB-rip-200] import-route direct

[RouterB-rip-200] quit

# Display the routing table of Router C.

[RouterC] display ip routing-table

Routing Tables: Public

Destinations : 8 Routes : 8

Destination/Mask Proto Pre Cost NextHop Interface

10.2.1.0/24 RIP 100 1 12.3.1.1 GE3/1/1

11.1.1.0/24 RIP 100 1 12.3.1.1 GE3/1/1

12.3.1.0/24 Direct 0 0 12.3.1.2 GE3/1/1

12.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

16.4.1.0/24 Direct 0 0 16.4.1.1 GE3/1/2

16.4.1.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

4. Configure a filtering policy for redistributed routes:

# On Router B, define ACL 2000 and reference it to a filtering policy to filter routes redistributed from RIP 100, making the route not advertised to Router C.

[RouterB] acl number 2000

[RouterB-acl-basic-2000] rule deny source 10.2.1.1 0.0.0.255

[RouterB-acl-basic-2000] rule permit

[RouterB-acl-basic-2000] quit

[RouterB] rip 200

[RouterB-rip-200] filter-policy 2000 export rip 100

# Display the routing table on Router C.

[RouterC] display ip routing-table

Routing Tables: Public

Destinations : 7 Routes : 7

Destination/Mask Proto Pre Cost NextHop Interface

11.1.1.0/24 RIP 100 1 12.3.1.1 GE3/1/1

12.3.1.0/24 Direct 0 0 12.3.1.2 GE3/1/1

12.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

16.4.1.0/24 Direct 0 0 16.4.1.1 GE3/1/2

16.4.1.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

Configuring an additional metric for a RIP interface

Network requirements

As shown in the following figure:

· RIPv2 is enabled on all the interfaces of Router A, Router B, Router C, Router D, and Router E.

· Router A has two links to Router D. The link from Router B to Router D is more stable than that from Router C to Router D. Configure an additional metric for RIP routes received through GigabitEthernet 3/1/2 on Router A so that Router A prefers the network 1.1.5.0/24 learned from Router B.

Figure 7 Network diagram

Configuration procedure

1. Configure IP addresses for the interfaces. (Details not shown)

2. Configure RIP basic functions:

# Configure Router A.

<RouterA> system-view

[RouterA] rip

[RouterA-rip-1] network 1.0.0.0

[RouterA-rip-1] version 2

[RouterA-rip-1] undo summary

[RouterA-rip-1] quit

# Configure Router B.

<RouterB> system-view

[RouterB] rip

[RouterB-rip-1] network 1.0.0.0

[RouterB-rip-1] version 2

[RouterB-rip-1] undo summary

# Configure Router C.

<RouterC> system-view

[RouterB] rip

[RouterC-rip-1] network 1.0.0.0

[RouterC-rip-1] version 2

[RouterC-rip-1] undo summary

# Configure Router D.

<RouterD> system-view

[RouterD] rip

[RouterD-rip-1] network 1.0.0.0

[RouterD-rip-1] version 2

[RouterD-rip-1] undo summary

# Configure Router E.

<RouterE> system-view

[RouterE] rip

[RouterE-rip-1] network 1.0.0.0

[RouterE-rip-1] version 2

[RouterE-rip-1] undo summary

# Display the IP routing table of Router A.

[RouterA] display rip 1 database

1.0.0.0/8, cost 0, ClassfulSumm

1.1.1.0/24, cost 0, nexthop 1.1.1.1, Rip-interface

1.1.2.0/24, cost 0, nexthop 1.1.2.1, Rip-interface

1.1.3.0/24, cost 1, nexthop 1.1.1.2

1.1.4.0/24, cost 1, nexthop 1.1.2.2

1.1.5.0/24, cost 2, nexthop 1.1.1.2

1.1.5.0/24, cost 2, nexthop 1.1.2.2

The output shows that two RIP routes can reach network 1.1.5.0/24. Their next hops are Router B (1.1.1.2) and Router C (1.1.2.2) respectively, with the same cost of 2. Router C is the next hop router to reach network 1.1.4.0/24, with a cost of 1.

3. Configure an additional metric for the RIP interface:

# Configure an additional metric of 3 for GigabitEthernet 3/1/2 on Router A.

[RouterA] interface GigabitEthernet 3/1/2

[RouterA-GigabitEthernet3/1/2] rip metricin 3

[RouterA-GigabitEthernet3/1/2] display rip 1 database

1.0.0.0/8, cost 0, ClassfulSumm

1.1.1.0/24, cost 0, nexthop 1.1.1.1, Rip-interface

1.1.2.0/24, cost 0, nexthop 1.1.2.1, Rip-interface

1.1.3.0/24, cost 1, nexthop 1.1.1.2

1.1.4.0/24, cost 2, nexthop 1.1.1.2

1.1.5.0/24, cost 2, nexthop 1.1.1.2

The output shows that only one RIP route reaches network 1.1.5.0/24, with the next hop as Router B (1.1.1.2) and a cost of 2.

Configuring RIP to advertise a summary route

Network requirements

As shown in the following figure:

· Router A and Router B run OSPF, Router D runs RIP, and Router C runs OSPF and RIP.

· Configure RIP to redistribute OSPF routes on Router C so that Router D has routes destined for networks 10.1.1.0/24, 10.2.1.0/24, 10.5.1.0/24, and 10.6.1.0/24.

· Route summarization is configured on Router C and only the summary route 10.0.0.0/8 is advertised, reducing the routing table size of Router D.

Figure 8 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown)

2. Configure OSPF basic functions:

# Configure Router A.

<RouterA> system-view

[RouterA] ospf

[RouterA-ospf-1] area 0

[RouterA-ospf-1-area-0.0.0.0] network 10.5.1.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] quit

# Configure Router B.

<RouterB> system-view

[RouterB] ospf

[RouterB-ospf-1] area 0

[RouterB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] network 10.6.1.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] quit

# Configure Router C.

<RouterC> system-view

[RouterC] ospf

[RouterC-ospf-1] area 0

[RouterC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255

[RouterC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255

[RouterC-ospf-1-area-0.0.0.0] quit

3. Configure RIP basic functions:

# Configure Router C.

<RouterC> system-view

[RouterC] rip 1

[RouterC-rip-1] network 11.3.1.0

[RouterC-rip-1] version 2

[RouterC-rip-1] undo summary

# Configure Router D.

<RouterD> system-view

[RouterD] rip 1

[RouterD-rip-1] network 11.0.0.0

[RouterD-rip-1] version 2

[RouterD-rip-1] undo summary

[RouterD-rip-1] quit

# Configure RIP to redistribute the routes from OSPF process 1 and direct routes on Router C.

[RouterC-rip-1] import-route direct

[RouterC-rip-1] import-route ospf 1

# Display the routing table information of Router D.

[RouterD] display ip routing-table

Routing Tables: Public

Destinations : 10 Routes : 10

Destination/Mask Proto Pre Cost NextHop Interface

10.1.1.0/24 RIP 100 1 11.3.1.1 GE3/1/1

10.2.1.0/24 RIP 100 1 11.3.1.1 GE3/1/1

10.5.1.0/24 RIP 100 1 11.3.1.1 GE3/1/1

10.6.1.0/24 RIP 100 1 11.3.1.1 GE3/1/1

11.3.1.0/24 Direct 0 0 11.3.1.2 GE3/1/1

11.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.4.1.0/24 Direct 0 0 11.4.1.2 GE3/1/2

11.4.1.2/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

4. Configure route summarization on Router C and advertise only the summary route 10.0.0.0/8:

[RouterC] interface GigabitEthernet 3/1/2

[RouterC-GigabitEthernet3/1/2] rip summary-address 10.0.0.0 8

# Display the routing table information of Router D.

[RouterD] display ip routing-table

Routing Tables: Public

Destinations : 7 Routes : 7

Destination/Mask Proto Pre Cost NextHop Interface

10.0.0.0/8 RIP 100 1 11.3.1.1 GE3/1/1

11.3.1.0/24 Direct 0 0 11.3.1.2 GE3/1/1

11.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.4.1.0/24 Direct 0 0 11.4.1.2 GE3/1/2

11.4.1.2/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

Configuring RIP FRR

Network requirements

Router S, Router A, and Router D are interconnected through RIPv2, as illustrated in Figure 9. Configure RIP FRR so that when Link A between Router S and Router D fails, traffic can be switched to Link B immediately.

Figure 9 Network diagram

Configuration procedure

1. Configure IP addresses for the interfaces on each router and configure RIPv2:

Follow Figure 9 to configure the IP address and subnet mask of each interface on the routers. (Details not shown)

Configure RIPv2 on the routers, making sure that Router A, Router D, and Router S can communicate with each other at Layer 3. (Details not shown)

2. Configure RIP FRR:

# Configure Router S.

<RouterS> system-view

[RouterS] bfd echo-source-ip 1.1.1.1

[RouterS] ip ip-prefix abc index 10 permit 4.4.4.4 32

[RouterS] route-policy frr permit node 10

[RouterS-route-policy] if-match ip-prefix abc

[RouterS-route-policy] apply fast-reroute backup-interface GigabitEthernet 3/1/1 backup-nexthop 12.12.12.2

[RouterS-route-policy] quit

[RouterS] rip 1

[RouterS-rip-1] fast-reroute route-policy frr

[RouterS-rip-1] quit

# Configure Router D.

<RouterD> system-view

[RouterD] bfd echo-source-ip 4.4.4.4

[RouterD] ip ip-prefix abc index 10 permit 1.1.1.1 32

[RouterD] route-policy frr permit node 10

[RouterD-route-policy] if-match ip-prefix abc

[RouterD-route-policy] apply fast-reroute backup-interface GigabitEthernet 3/1/1 backup-nexthop 24.24.24.2

[RouterD-route-policy] quit

[RouterD] rip 1

[RouterD-rip-1] fast-reroute route-policy frr

[RouterD-rip-1] quit

3. Verify the configuration:

# Display route 4.4.4.4/32 on Router S and you can view the backup next hop information.

[RouterS] display ip routing-table 4.4.4.4 verbose

Routing Table : Public

Summary Count : 1

Destination: 4.4.4.4/32

Protocol: RIP Process ID: 1

Preference: 100 Cost: 1

NextHop: 13.13.13.2 Interface: GigabitEthernet3/1/2

BkNextHop: 12.12.12.2 BkInterface: GigabitEthernet3/1/1

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

State: Active Adv Age: 00h01m27s

Tag: 0

# Display route 1.1.1.1/32 on Router D. You can find the backup next hop information.

[RouterS] display ip routing-table 1.1.1.1 verbose

Routing Table : Public

Summary Count : 1

Destination: 1.1.1.1/32

Protocol: RIP Process ID: 1

Preference: 100 Cost: 1

NextHop: 13.13.13.1 Interface: GigabitEthernet3/1/2

BkNextHop: 24.24.24.2 BkInterface: GigabitEthernet3/1/1

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

State: Active Adv Age: 00h01m27s

Tag: 0

Configuring BFD for RIP (single-hop detection in BFD echo packet mode)

Network requirements

As shown in the following figure:

· Router A and Router C are interconnected through Router D. GigabitEthernet 4/1/1 of the two routers runs RIP process 1, BFD is enabled on GigabitEthernet 4/1/1 of Router A.

· Router A is connected to Router C through Router B. GigabitEthernet 4/1/2 on Router A runs RIP process 2; GigabitEthernet 4/1/2 on Router C, and GigabitEthernet 4/1/1 and GigabitEthernet 4/1/2 on Router B run RIP process 1.

· Configure a static route and enable static route redistribution into RIP on Router C. Router A learns the static route sent by Router C, and the outbound interface of the route is the interface connected to Router D.

· When the link between Router C and Router D fails, BFD can quickly detect the link failure and notify it to RIP, and the BFD session goes down. In response, RIP deletes the neighbor relationship with Router C and the route information received from Router C. Then, Router A learns the static route from Router C with the outbound interface being the interface connected to Router B.

Figure 10 Network diagram

Configuration procedure

1. Configure RIP basic functions and enable BFD on the interfaces:

# Configure Router A.

<RouterA> system-view

[RouterA] rip 1

[RouterA-rip-1] network 192.168.1.0

[RouterA-rip-1] quit

[RouterA] interface GigabitEthernet 4/1/1

[RouterA-GigabitEthernet4/1/1] rip bfd enable

[RouterA-GigabitEthernet4/1/1] quit

[RouterA] rip 2

[RouterA-rip-2] network 192.168.2.0

[RouterA-rip-2] quit

# Configure Router B.

<RouterB> system-view

[RouterB] rip 1

[RouterB-rip-1] network 192.168.2.0

[RouterB-rip-1] network 192.168.3.0

[RouterB-rip-1] quit

# Configure Router C.

<RouterC> system-view

[RouterC] rip 1

[RouterC-rip-1] network 192.168.1.0

[RouterC-rip-1] network 192.168.3.0

[RouterC-rip-1] import-route static

[RouterC-rip-1] quit

2. Configure the BFD parameters on GigabitEthernet 4/1/1 of Router A:

[RouterA] bfd session init-mode active

[RouterA] bfd echo-source-ip 11.11.11.11

[RouterA] interface GigabitEthernet 4/1/1

[RouterA-GigabitEthernet4/1/1] bfd min-transmit-interval 500

[RouterA-GigabitEthernet4/1/1] bfd min-receive-interval 500

[RouterA-GigabitEthernet4/1/1] bfd detect-multiplier 7

[RouterA-GigabitEthernet4/1/1] return

3. Configure a static route on Router C:

[RouterC] ip route-static 100.1.1.1 24 null 0

4. Verify the configuration:

# Display the BFD session information of Router A.

<RouterA> display bfd session

Total Session Num: 1 Init Mode: Active

Session Working Under Echo Mode:

LD SourceAddr DestAddr State Holdtime Interface

3 192.168.1.1 192.168.1.2 Up 2000ms GE4/1/1

# Display the RIP route 100.1.1.0/24 learned on Router A.

<RouterA> display ip routing-table 100.1.1.0 24 verbose

Routing Table : Public

Summary Count : 2

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 1

Preference: 100 Cost: 1

NextHop: 192.168.1.2 Interface: GigabitEthernet4/1/1

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 192.168.1.2

Tunnel ID: 0x0 Label: NULL

State: Active Adv Age: 00h00m47s

Tag: 0

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 2

Preference: 100 Cost: 2

NextHop: 192.168.2.2 Interface: GigabitEthernet4/1/2

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 192.168.2.2

Tunnel ID: 0x0 Label: NULL

State: Inactive Adv Age: 00h12m50s

Tag: 0

# Enable RIP event debugging on Router A.

<RouterA> debugging rip 1 event

<RouterA> terminal debugging

# When the link between Router C and the Layer 2 switch fails, Router A quickly detects the link state change.

%Jan 19 10:41:51:203 2008 RouterA BFD/4/LOG:Sess[192.168.1.1/192.168.1.2, GE4/1/1,Ctrl], Sta: UP->DOWN, Diag: 1

*Jan 19 10:33:12:813 2008 RouterA RM/6/RMDEBUG: RIP-BFD: Message Type Disable, Connect Type Direct-connect, Pkt Type Echo, Src IP Address 192.168.1.1, Src IFIndex4, Nbr IP Address 192.168.1.2.

# Display the BFD information of Router A.

Router A has deleted the neighbor relationship with Router C and no output information is displayed.

<RouterA> display bfd session

# Display the RIP routes of RIP process 1 on Router A.

The RIP route learned from Router C is no longer existent.

<RouterA> display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

# Display the RIP route 100.1.1.0/24 learned on Router A.

<RouterA> display ip routing-table 100.1.1.0 24 verbose

Routing Table : Public

Summary Count : 1

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 2

Preference: 100 Cost: 2

NextHop: 192.168.2.2 Interface: GigabitEthernet4/1/2

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 192.168.2.2

Tunnel ID: 0x0 Label: NULL

State: Active Adv Age: 00h18m40s

Tag: 0

Configuring BFD for RIP (bidirectional detection in BFD control packet mode)

Network requirements

As shown in the following figure:

· Router A is connected to Router C through Router B. GigabitEthernet 4/1/2 on Router A and GigabitEthernet 4/1/1 on Router C run RIP process 1.

· Configure a static route to Router C on Router A, and configure a static route to Router A on Router C. Enable BFD on GigabitEthernet 4/1/2 of Router A and GigabitEthernet 4/1/1 of Router C.

· Router A is connected to Router C through Router D. GigabitEthernet 4/1/1 on Router A runs RIP process 2; GigabitEthernet 4/1/2 on Router C, and GigabitEthernet 4/1/1 and GigabitEthernet 4/1/2 on Router D run RIP process 1.

· Enable static route redistribution into RIP on Router A and Router C so that Router A and Router C have routes to send to each other. Router A learns the static route sent by Router C, the outbound interface is the interface connected to Router B.

· When the link between Router B and Router C fails, BFD can quickly detect the link failure and notify it to RIP, and the BFD session goes down. In response, RIP deletes the neighbor relationship with Router C and the route information received from Router C. Then, Router A learns the static route sent by Router C, and the outbound interface of the route is the interface connected to Router D.

Figure 11 Network diagram

Configuration procedure

1. Configure RIP basic functions and enable static route redistribution into RIP so that Router A and Router C have routes to send to each other:

# Configure Router A.

<RouterA> system-view

[RouterA] rip 1

[RouterA-rip-1] network 192.168.1.0

[RouterA-rip-1] peer 192.168.2.2

[RouterA-rip-1] undo validate-source-address

[RouterA-rip-1] import-route static

[RouterA-rip-1] quit

[RouterA] interface GigabitEthernet 4/1/2

[RouterA-GigabitEthernet4/1/2] rip bfd enable

[RouterA-GigabitEthernet4/1/2] quit

[RouterA] rip 2

[RouterA-rip-2] network 192.168.3.0

[RouterA-rip-2] quit

# Configure Router C.

<RouterC> system-view

[RouterC] rip 1

[RouterC-rip-1] network 192.168.2.0

[RouterC-rip-1] network 192.168.4.0

[RouterC-rip-1] peer 192.168.1.1

[RouterC-rip-1] undo validate-source-address

[RouterC-rip-1] import-route static

[RouterC-rip-1] quit

[RouterC] interface GigabitEthernet 4/1/1

[RouterC-GigabitEthernet4/1/1] rip bfd enable

[RouterC-GigabitEthernet4/1/1] quit

# Configure Router D.

<RouterC> system-view

[RouterC] rip 1

[RouterC-rip-1] network 192.168.3.0

[RouterC-rip-1] network 192.168.4.0

[RouterC-rip-1] quit

2. Configure IP addresses and BFD parameters for the interfaces:

# Configure Router A.

[RouterA] bfd session init-mode active

[RouterA] interface GigabitEthernet 4/1/1

[RouterA-GigabitEthernet4/1/1] ip address 192.168.3.1 24

[RouterA-GigabitEthernet4/1/1] quit

[RouterA] interface GigabitEthernet 4/1/2

[RouterA-GigabitEthernet4/1/2] ip address 192.168.1.1 24

[RouterA-GigabitEthernet4/1/2] bfd min-transmit-interval 500

[RouterA-GigabitEthernet4/1/2] bfd min-receive-interval 500

[RouterA-GigabitEthernet4/1/2] bfd detect-multiplier 7

[RouterA-GigabitEthernet4/1/2] quit

# Configure Router B.

<RouterB> system-view

[RouterB] interface GigabitEthernet 4/1/2

[RouterB-GigabitEthernet4/1/2] ip address 192.168.1.2 24

[RouterB-GigabitEthernet4/1/2] quit

[RouterB] interface GigabitEthernet 4/1/1

[RouterB-GigabitEthernet4/1/1] ip address 192.168.2.1 24

# Configure Router C.

[RouterC] bfd session init-mode active

[RouterC] interface GigabitEthernet 4/1/1

[RouterC-GigabitEthernet4/1/1] ip address 192.168.2.2 24

[RouterC-GigabitEthernet4/1/1] bfd min-transmit-interval 500

[RouterC-GigabitEthernet4/1/1] bfd min-receive-interval 500

[RouterC-GigabitEthernet4/1/1] bfd detect-multiplier 6

[RouterC-GigabitEthernet4/1/1] quit

[RouterC] interface GigabitEthernet 4/1/2

[RouterC-GigabitEthernet4/1/2] ip address 192.168.4.2 24

[RouterC-GigabitEthernet4/1/2] quit

# Configure Router D.

<RouterD> system-view

[RouterD] interface GigabitEthernet 4/1/2

[RouterD-GigabitEthernet4/1/2] ip address 192.168.4.1 24

[RouterD-GigabitEthernet4/1/2] quit

[RouterD] interface GigabitEthernet 4/1/1

[RouterD-GigabitEthernet4/1/1] ip address 192.168.3.2 24

[RouterD-GigabitEthernet4/1/1] quit

3. Configure static routes:

# Configure a static route to Router C on Router A.

[RouterA] ip route-static 192.168.2.0 24 GigabitEthernet4/1/2 192.168.1.2

[RouterA] ip route-static 101.1.1.1 24 null 0

[RouterA] quit

# Configure a static route to Router A on Router C.

[RouterC] ip route-static 192.168.1.0 24 GigabitEthernet4/1/1 192.168.2.1

[RouterC] ip route-static 100.1.1.1 24 null 0

CAUTION:

If you specify null 0 interface as the output interface for a static route, do not specify the IP address of a directly connected network as the destination IP address.

4. Verify the configuration:

# Display the BFD session information of Router A.

<RouterA> display bfd session

Total Session Num: 1 Init Mode: Active

Session Working Under Ctrl Mode:

LD/RD SourceAddr DestAddr State Holdtime Interface

6/1 192.168.1.1 192.168.2.2 Up 1700ms GE4/1/2

# Display the RIP route 100.1.1.0/24 learned on Router A.

<RouterA> display ip routing-table 100.1.1.0 verbose

Routing Table : Public

Summary Count : 2

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 1

Preference: 100 Cost: 1

NextHop: 192.168.2.2 Interface: GigabitEthernet4/1/2

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 192.168.1.2 Neighbor : 192.168.2.2

Tunnel ID: 0x0 Label: NULL

State: Active Adv GotQ Age: 00h04m02s

Tag: 0

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 2

Preference: 100 Cost: 2

NextHop: 192.168.3.2 Interface: GigabitEthernet4/1/1

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 192.168.3.2

Tunnel ID: 0x0 Label: NULL

State: Inactive Adv Age: 00h03m57s

Tag: 0

# Enable RIP event debugging on Router A.

<RouterA> debugging rip 1 event

<RouterA> terminal debugging

# When the link between Router B and Router C fails, Router A quickly detects the link state change.

%Jan 19 10:41:51:203 2008 RouterA BFD/4/LOG:Sess[192.168.1.1/192.168.2.2, GE4/1/2, Ctrl], Sta: UP->DOWN, Diag: 1

*Jan 19 10:41:51:203 2008 RouterA RM/6/RMDEBUG: RIP-BFD: Message Type Disable, Connect Type Indirect-connect, Pkt Type Control, Src IP Address 192.168.1.1, Src IFIndex 4, Nbr IP Address 192.168.2.2.

# Display the BFD information of Router A.

Router A has deleted the neighbor relationship with Router C and no output information is displayed.

<RouterA> display bfd session

# Display the RIP routes of RIP process 1 on Router A.

The RIP route learned from Router C is no longer existent.

<RouterA> display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

# Display the RIP route 100.1.1.0/24 learned on Router A.

<RouterA> display ip routing-table 100.1.1.0 verbose

Routing Table : Public

Summary Count : 1

Destination: 100.1.1.0/24

Protocol: RIP Process ID: 2

Preference: 100 Cost: 2

NextHop: 192.168.3.2 Interface: GigabitEthernet4/1/2

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 192.168.3.2

Tunnel ID: 0x0 Label: NULL

State: Active Adv Age: 00h10m35s

Tag: 0

Troubleshooting RIP

No RIP updates received

Symptom

No RIP updates are received when the links work properly.

Analysis

After enabling RIP, you must use the network command to enable corresponding interfaces. Make sure no interfaces are disabled from handling RIP messages.

If the peer is configured to send multicast messages, the same should be configured on the local end.

Solution

1. Use the display current-configuration command to check RIP configuration

2. Use the display rip command to check whether an interface is disabled

Route oscillation occurred

Symptom

When all links work properly, route oscillation occurs on the RIP network. After displaying the routing table, you might find some routes intermittently appear and disappear in the routing table.

Analysis

In the RIP network, make sure that all the same timers within the entire network are identical and have logical relationships between them. For example, the timeout timer value should be greater than the update timer value.

Solution

1. Use the display rip command to check the configuration of RIP timers

2. Use the timers command to adjust timers properly.

06-Layer 3 - IP Routing Configuration Guide

RIP overview

RIP working mechanism

Introduction

RIP routing table

Routing loops prevention

RIP operation

RIP versions

RIP message format

RIPv1 message format

RIPv2 message format

RIPv2 authentication message format

Working mechanism

Message types

TRIP retransmission mechanism

Configuring RIP basic functions

Configuration procedure

Enabling RIP and a RIP interface

Configuring the interface behavior

Configuring a RIP version

Configuring RIP route control

Configuring an additional routing metric

Configuring RIPv2 route summarization

Enabling RIPv2 route automatic summarization

Advertising a summary route

Disabling host route reception

Configuring inbound/outbound route filtering

Configuring a priority for RIP

Configuring RIP route redistribution

Tuning and optimizing RIP networks

Configuring RIP timers

Configuring split horizon and poison reverse

Enabling split horizon

Enabling poison reverse

Configuring the maximum number of load balanced routes

Enabling zero field check on incoming RIPv1 messages

Enabling source IP address check on incoming RIP updates

Specifying a RIP neighbor

Configuring TRIP

Enabling TRIP

Configuring TRIP retransmission parameters

Configuring RIP-to-MIB binding

Configuring RIP FRR

Configuration prerequisites

Configuration procedure

Configuring BFD for RIP

RIP configuration examples

Network requirements

Configuring RIP route redistribution

Network requirements

Configuration procedure

Configuring an additional metric for a RIP interface

Network requirements

Configuration procedure

Network requirements

Configuration procedure

Configuring RIP FRR

Network requirements

Configuration procedure

Configuring BFD for RIP (single-hop detection in BFD echo packet mode)

Network requirements

Configuration procedure

Network requirements

Configuration procedure

Symptom

Analysis

Solution

Symptom

Analysis

Solution

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