The Routing Information Protocol (RIP) is an Interior Gateway Protocol (IGP). This document discusses both RIP and Triggered RIP. OpenROUTE software supports RIP Version 1 (RIPv1), RIP Version 2 (RIPv2), Triggered RIPv1, and Triggered RIPv2. The document includes the following topics:

Interior Gateway Protocols

Most router loads contain one IGP for building the IP routing table and that is RIP. However, many of the OpenROUTE software loads contain both RIP and OSPF. The Bellman-Ford or the distance-vector algorithm is the basis for RIP. Link-state technology or the Shortest-Path First (SPF) algorithm is the basis for the Open Shortest Path First (OSPF) protocol. Routers can run OSPF and RIP simultaneously.

The Routing Information Protocol (RIP)

Destinations may be either networks or a special destination used to convey a default route. RIP, like OSPF, does not alter IP packets and routes them based on destination address only.

Distance-vector algorithms make each router periodically broadcast its routing tables to all its neighbors. Then a router knowing its neighbors' tables can decide which destination neighbor to use for routing a packet.

Limitations

• Limits an Autonomous System (AS) diameter to 15 hops.

• Can result in sub-optimal routing because the hop count cannot adequately describe variations in a path's characteristics.

• Finds new routes slowly when the network changes. This search consumes considerable bandwidth, and, in extreme cases, exhibits a slow convergence behavior referred to as a count to infinity.

• Does not carry a subnet mask. Therefore, any subnet mask information can only be derived from the router's configuration.

• Requires that all router interfaces running RIPv1 and configured with IP addresses in the same network class must be configured with the same subnet mask.

• Requires that routes be aggregated to the network class boundary when routes are sent out over an interface of a different class.

• Carries a subnet mask.

• Supports password authentication security.

• Specifies the next hop address.

• Does not require that routes be aggregated on the network boundary.

Subnet Mask

With RIPv1, the interface's routing information does not contain a subnet mask; thus, the interface's subnet mask is not known to routers or systems outside the interface's own network. Such routers or systems assume that the subnet mask for the interface is the same as its network class mask. If the sending interface is in the same network as the interface receiving the RIP packet, however, it assumes that the subnet mask is the same as that configured for the destination interface.

With RIPv2, the RIPv1 restriction that router interfaces configured with addresses contained in the same network class have the same subnet mask no longer applies. Therefore, if you need variable subnet masks on the different router interfaces, you should configure RIPv2 to run on these interfaces.

With RIPv1, routing advertisements must be aggregated on the network class boundary when advertised outside the network. This is exactly what you need if your network class is completely contiguous, and there are no intervening networks that separate your network into non-contiguous segments.

However, if your network class is not contiguous, RIPv1 does not work since it has no subnet mask, and it must aggregate advertisements on the network class boundary. RIPv2 solves this problem and can be used to advertise the individual subnets that comprise each of the separate, non-contiguous segments of your network class.

Note: The ability to advertise subnets is something that OSPF could always do. You now have this ability by using RIPv2. OSPF is the superior routing protocol for large networks, but if you have a small or medium-sized network, RIPv2 may satisfy your needs if the ability to advertise subnets was the key criterion in your choice between RIP and OSPF.

Next Hop

When Should I Choose RIPv1 Over RIPv2?

• Choose RIPv1 if you want routing advertisements to be aggregated on the network class boundary. Otherwise, choose RIPv2.

• Configure all the router interfaces on the same physical IP network to run either RIPv1 or RIPv2, but not both.

• Configure your router to run both RIPv1 and RIPv2 if there are routers on the same physical network that must use RIPv1 and others that must use RIPv2. Setting the Both option allows your router to interoperate with the RIPv1 routers and also the RIPv2 routers at the same time.

The set of routes sent out from a particular address is the union of the routes selected by setting any of the flags described in Table 1. At the RIP Config> prompt, you use the enable/disable sending commands to configure RIP send flags.

Table 40 RIP Send Flags

Flag	If enabled, the interface . . .
Send All Routes	Sends all routes in RIP responses.
Send Default Routes	Advertises a default route in RIP responses if the router itself has a default gateway in operation. The router advertises the route to the default (authoritative) gateway as a route to destination 0.0.0.0.
Send Host Routes	Sends all host routes in RIP responses. (Usually only used with RIPv2.)
Send Net Routes	Sends all network-level routes in RIP responses.
Send Poisoned-Reverse Routes	Sends poisoned-reverse routes in RIP responses. (You can disable this flag if necessary.)
Send Static Routes	Advertises all directly connected networks and statically configured routes in RIP responses.
Send Subnet Routes	Sends appropriate subnet-level routes in RIP responses.

The flags described in Table 2 control how the router incorporates information that RIP receives into its routing tables. At the RIP Config> prompt, you use the enable/disable receiving commands to configure RIP receive flags.

Table 41 RIP Receive Flags

Flag	If disabled, the interface ...
Receive RIP	Ignores RIP packets received on the specified interface.
Receive All Dynamic Routes	Accepts RIP updates for all routes specified by the add accept-rip route command.
Receive Dynamic Host Routes	Accepts RIP updates only for those hosts specified by the add accept-rip route command.
Receive Dynamic Net Routes	Accepts RIP updates only for those networks specified by the add accept-rip route command.
Receive Dynamic Subnet Routes	Accepts RIP updates only for those subnets specified by the add accept-rip route command.

The flags described in Table 3 also control how the router incorporates information that RIP receives into its routing tables. Certain flag settings allow RIP routes to override static routing information, but only if the RIP metric is better than the static route's metric. At the RIP Config> prompt, you use the enable/disable override commands to configure RIP override flags.

Table 42 Override Flags

Flag	If enabled, RIP packets received on the interface ...
Override Default	May override the router's default gateway.
Override Static Routes	May override any of the router's statically configured routing information.

Triggered RIP

• Consume a lot of bandwidth on point-to-point lines.

• Interfere with normal data flow and run up the usage charge on demand circuits by always keeping the link up in order to exchange routing information.

Notes:

• OpenROUTE software allows you to configure either Triggered RIPv1 or Triggered RIPv2.

• Triggered RIP runs only on a point-to-point WAN connection between two and only two routers. This means that it runs over a PPP interface or a Frame Relay interface that consists of a single Data Link Connection Identifier (DLCI).

• Although Triggered RIP is similar to RIP, it is a completely different protocol. RIP and Triggered RIP are incompatible.

• You must set the Triggered RIP send-option on routers at both ends of the link.

• No Route Aging. The router treats all routes that it learns via Triggered RIP responses as permanent. That is, the routes do not age like routes that are learned across broadcast media and that get refreshed every 30 seconds.

• Route Acknowledgment. Triggered RIP neighbors must acknowledge all routing updates. This implies that RIP cannot clear a deleted route from the routing table unless all of its neighbors have acknowledged the update.

  However, if the router cannot make contact with a neighbor after a configured number of times, it clears its routes.

• Retransmission. All Triggered RIP update responses are retransmitted until they are acknowledged.

• Sub-optimal Routes. To take full advantage of Triggered RIP, for faster convergence, OpenROUTE software retains all alternate or sub-optimal routes that your router learns across Triggered RIP interfaces. Otherwise, a request for a full routing table update would have to be sent to all Triggered RIP neighbors each time a route is deleted from the database.

1. At the Config> prompt, enter protocol ip.

Config>protocol ip
Internet protocol user configuration
IP config>rip

2. At the IP config> prompt, enter rip.

Config>protocol ip
Internet protocol user configuration

IP config>rip
RIP config>

1. At the Monitor> prompt, enter protocol ip.

Monitor>protocol ip
IP>

2. At the IP> prompt, enter rip.

IP>rip
RIP>

1. Enable RIP with the following command. The default is to use RIP v2.

RIP Config>enable rip

2. Enable or disable the various flags.

By default, RIP advertises all network and subnet routes out all interfaces of the router that have assigned IP addresses or are using unnumbered IP. Once you enable RIP, you can configure what it listens to and what it advertises by setting the various RIP flags. Configure these flags for each interface.

For information on the send, receive, and override flags, see Table 1, Table 2, and Table 3 respectively.

3. If your network is using RIP, and your connected network is using another routing protocol (such as OSPF, EGP, or BGP) to establish (originate) a single default route to that network, enter the set originate-rip-default command.

RIP config>set originate-rip-default
Always originate default route? [No]:
Originate default if EGP/BGP routes available? [No]: y
   From AS number [0]?
   To network number [0.0.0.0]?
Originate default if OSPF routes available? [No]:
Cost [1]?
RIPv2 next hop [0.0.0.0]?

You need to originate a RIP default route for the other routing protocols to which your network may be connected. This default route directs traffic bound for a non-RIP network to a boundary router that functions as a portal. Originating a single default route means that the boundary router does not have to distribute the other network's routing information to the other nodes on its network.

Answering Yes means a default route is always originated (that is, defaults to previous behavior). Answering Yes to the EGP/BGP question originates a default whenever there are EGP or BGP routes in the routing table. Answering Yes to if OSPF routes available causes the RIP default to be advertised when OSPF routes are in the routing table. When the router originates a RIP default, it uses the original default cost number.

4. If you are using Triggered RIP, you must set the send-option for Triggered V1 or V2 and the receive-option for V1 or V2.

RIP config>set send-option trigV1
Interface address [0.0.0.0]?11.2.84.42
RIP config>set receive-option V1
Interface address [0.0.0.0]?11.2.84.42

You can verify the information you configured with the list protocol command.

RIP config>list protocol

Press Space twice after you type a command to display the available options for the command. Enter help for information about using the command line interface.

[C] means the command is available at the RIP config> prompt.

[M] means the command is available at the RIP> prompt.

Table 4 lists the RIP commands.

Table 43 RIP Commands

Command	Function
Add [C]	Adds a RIP interface and the acceptance of a RIP route.
Clear [C] [M]	At the RIP Config> prompt, clears all RIP information on all interfaces and resets all settings, including flags, to default settings. (If RIP is enabled, this command still clears RIP information, but RIP remains enabled.) At the RIP> prompt, clears counters.
Delete [C]	Deletes a RIP interface and the acceptance of a RIP route.
Disable [C]	Disables RIP, a selected RIP interface, or the receiving or sending of RIP packets.
Dump [M]	Dumps routing tables.
Enable [C]	Enables RIP, a selected RIP interface, or the receiving or sending of RIP packets.
Interface [M]	Displays an interface summary.
List [C]	Lists RIP configuration information.
Neighbor [M]	Displays summary information on the router's neighbors.
Ping [M]	Sends requests to a designated address and waits for a response.
Route [M]	Routes a particular network address.
Set [C]	Sets RIP configuration parameters.
Statistics [M]	Displays RIP statistics on the router.
Traceroute [M]	Displays information on the routing destination path(s).

Add [C]

Syntax: add

accept-rip-route

interface

Note: This command has no effect if there are no disable receiving dynamic command settings

Network number [0.0.0.0]? 128.185.227.21

Example: add interface

Interface address [0.0.0.0]? 128.185.227.21

Clear [C]

Note: If you enabled RIP, it remains enabled after you use this command. All RIP parameters are set to default settings.

All configured interface records will be deleted;  RIP will use
the default values for subsequent restarts.
Are you sure you want to delete them (Yes or [No]):

Syntax: clear

Specify nothing to clear global counters, or 'Interface ip_addr' to clear interface counters, or 'Neighbor ip_addr' to clear neighbor counters.

Syntax: delete

accept-rip-route

interface

Example: delete accept-rip-route

Enter the address to be deleted [0.0.0.0]?128.185.227.10

Example: delete interface

Interface address [0.0.0.0]?128.185.227.16

Syntax: disable

interface

override default

override static routes

receiving dynamic

receiving rip

rip

sending

Example: disable interface

Interface address [0.0.0.0]? 128.185.220.45

Example: disable override default

Set for which interface address [0.0.0.0]?128.185.223.67

Example: disable override static-routes

Set for which interface address [0.0.0.0]?128.185.223.67

Example: disable receiving rip

Set for which interface address [0.0.0.0]?128.185.223.67

Syntax: receiving dynamic

all

hosts

nets

subnets

Set for which interface address [0.0.0.0]?128.185.220.64

rip

Example: disable rip

sending

Syntax: disable sending

all-routes

default-routes

host-routes

net-routes

poisoned-reverse-routes

subnet-routes

static-routes

Set for which interface address [0.0.0.0]?128.185.223.6

Note: You can turn off the net-routes, subnet-routes, and static-routes flags individually. If you specify a route by any of the enabled flags, OpenROUTE software advertises the route.

This command is available at the RIP> prompt for convenience. To display more information, enter this command at the IP Config> prompt. See Using IP.

Syntax: dump

Type   Dest net         Mask       Cost     Age   Next hop(s)

Sbnt   50.0.0.0         FF000000   1        0     None
 Dir*  50.10.1.0        FFFFFF00   1        0     Eth/0

Routing table size: 768 nets (64512 bytes), 2 nets known

Notes:

• An asterisk (*) after the route type indicates that the route has a static or directly connected backup. A percentage sign (%) after the route type indicates that the router always accepts RIP updates for this network or subnet.

• A number in parentheses at the end of the column indicates the number of equal-cost routes to the destination.

Syntax: enable

interface

override default

override static-routes

receiving dynamic

receiving rip

rip

sending

Note: When you enable RIP, in order to be compatible with previous releases, OpenROUTE software enables RIP on all IP interfaces by default.

Interface address [0.0.0.0]?128.185.225.63

Example: enable override default

Set for which interface address [0.0.0.0]?128.185.223.67

Example: enable override static-routes

Set for which interface address [0.0.0.0]?128.185.223.67

Example: enable receiving rip

Set for which interface address [0.0.0.0]?128.185.223.67

Syntax: enable receiving dynamic

all

hosts

nets

subnets

Set for which interface address [0.0.0.0]?128.185.227.23 

rip

Example: enable rip

Note: Use the enable sending or disable sending commands to configure the RIP routing update sending behavior. Use the enable receiving or disable receiving and the enable override or disable override commands to configure the RIP routing update receiving behavior.

Syntax: enable sending

all-routes

default-routes

host-routes

net-routes

poisoned-reverse-routes

subnet-routes

static-routes

Set for which interface address [0.0.0.0]?128.185.66.31 

Interface [M]

Syntax: interface

IP-Address       Intf   State   BadPkts  BadRtes  TrigUpdts  Nbrs (V1)

50.10.1.63       Eth/0  On      0        39663    13513      0     (0)

If you enter a specific interface address with the interface command, the software displays additional information on the designated interface.

Example: interface 50.10.1.65

IP-Address       Intf   State   BadPkts  BadRtes  TrigUpdts  Nbrs (V1)

50.10.1.6        Eth/0  On      0        39663    13513      0     (0)

Source Address:              50.10.1.65
Authentication Type:         None
Default cost:                0
Send option:                 V1&2
Receive option:              V1&2
Per-interface address flags: Send net and subnet routes
                             Receive No Dynamic host routes
Neighbors:                   None

Syntax: list

all

protocol

rip-routes-accept

Example: list all

RIP: enabled

Intf IP-address  Source-address   State  AuType  DefCost  Send    Recv

0    50.10.1.6   50.10.1.6        On     None    0        V1      V1

RIP default origination: disabled

Per-interface address flags:
  intf  0   50.10.1.6       Send net, subnet and host routes

Accept RIP updates always for:
  128.185.227.22    128.185.227.21

Note: When you run the list all and list protocol commands, the only
Per-interface address flags displayed are the enabled send flags and the disabled receive flags.

Example: list protocol

RIP: enabled

Intf IP-address  Source-address   State  AuType  DefCost  Send    Recv

0    50.10.1.65  50.10.1.65       On     None    0        V1      V1

RIP default origination: disabled

Per-interface address flags:
  intf  0   50.10.1.65       Send net, subnet and host routes 

rip-routes-accept

Example: list rip-routes-accept

Accept RIP updates always for:
  128.185.227.22    128.185.227.21

Syntax: neighbor

Neighbor-Addr        Phys    Vers  Age  BadPkts  BadRtes  RxSeq

128.185.223.1       PPP/0      V2  20   0        0        n/a
128.185.112.2       PPP/1      V2  10   0        0        n/a

Ping [M]

The ping process continues incrementing the ICMP sequence number with each additional packet. OpenROUTE software reports matching ICMP Echo responses received with their sequence number and the round-trip time. The process stops when you type a character. At that time, OpenROUTE displays a summary of packet loss, round-trip time, and the number of ICMP unreachable destinations. The round trip usually takes about 20 milliseconds (depending on the router platform).

When a destination has a multicast address, the software may display multiple responses for each packet sent, one for each member of the multicast group. Each response contains the source address of the responding system.

Note: The size of the ping (number of data bytes in the ICMP message, excluding the ICMP header) is 56 bytes, and the TTL is 60 seconds.

Syntax: ping interface-address

PING 128.185.142.11: 56 data bytes
64 bytes from 128.185.142.11: icmp_seq=0. time=0. ms
64 bytes from 128.185.142.11: icmp_seq=1. time=0. ms
64 bytes from 128.185.142.11: icmp_seq=2. time=0. ms
64 bytes from 128.185.142.11: icmp_seq=3. time=0. ms
64 bytes from 128.185.142.11: icmp_seq=4. time=0. ms
64 bytes from 128.185.142.11: icmp_seq=5. time=0. ms

----128.185.142.11 PING Statistics----
6 packets transmitted, 6 packets received, 0% packet loss
round-trip (ms)  min/avg/max = 0/0/0

This command is available at the RIP Config> prompt for convenience. To display more information, enter this command at the IP Config> prompt. See Using IP.

Syntax: route ip_destination_address

Destination:    50.10.1.0
Mask:           255.255.255.0
Route type:     Dir
Distance:       1
Age:            0
Next hop(s):    50.10.1.65        (Eth/0)
Tag:            0x00000000

Syntax: set

authentication

default-metric

max-retry

originate-rip-default

poll-timer

receive-option

reply-timer

send-option

source-address

Note: You should configure all routers on the same IP network with the same type of authentication.

none

simple-password

Interface address [0.0.0.0]?

Interface address [0.0.0.0]? 50.10.1.65
Authentication key? john
Enter Auth key again? john

default-metric

If you set the default metric to 0, OpenROUTE software uses the global default metric that you specified by the set-originate-rip-default command.

When you first define an interface, OpenROUTE software sets the default metric value for the interface to 0. If you specify the default metric, however, the defined metric takes precedence over the one you configured with the set originate-rip-default command. This applies for both RIPv1 and RIPv2.

Example: set default-metric

Interface address [0.0.0.0]? 50.10.1.65
Default metric (1-15), or 0 to use the global default [0]? 1

The range is 1-255. The default is 5.

Example: set max-retry

Interface address [0.0.0.0]? 50.10.1.65
Maximum number of retries (1-255) [36]? 5

This default route directs traffic bound for a non-RIP network to a boundary router that functions as a portal. Originating a single default route means that the boundary router does not have to distribute the other network's routing information to the other nodes on its network.

When you enter this command, the software prompts you to originate a RIP default route for the other routing protocols to which your network may be connected.

Note: The next hop field only exists in the RIPv2 packet format, not in RIPv1 packet format.

Example: set originate-rip-default

Always originate default route? [No]:
Originate default if EGP/BGP routes available? [No]:
Originate default if OSPF routes available? [No]:

Always originate default route? [No]: y
Cost [3]?
RIPv2 next hop [1.2.3.4]?

Always originate default route? [Yes]: n
Originate default if EGP/BGP routes available? [No]: y
   From AS number [0]?
   To network number [0.0.0.0]?
Originate default if OSPF routes available? [No]: y
Cost [3]?
RIPv2 next hop [1.2.3.4]?

The range is 1-3600 seconds. The default is 60 seconds.

Example: set poll-timer

Interface address [0.0.0.0]? 128.181.97.16
Poll Timer [30]?

Syntax: set receive-option

none

both

v1

v2

All interfaces (Yes or [No]):
Interface address [0.0.0.0]? 126.181.26.2

reply-timer

The range is 1-255 seconds. The default is 5 seconds.

Example: set reply-timer

Interface address [0.0.0.0]? 50.10.1.6
Reply Timer [5]?

Syntax: set send-option

none

both-v1v2

v1

v2

trigv1

trigv2

All interfaces (Yes or [No]):
Interface address [0.0.0.0]? 128.185.226.25

Note: Triggered RIP only runs on point-to-point interfaces. OpenROUTE software interprets Triggered RIPv1 and Triggered RIPv2 as RIPv1 and RIPv2 respectively on other interface types.

Note: The source address must be either one of the router's interface addresses or the router's internal IP address.

Example: set source-address

Interface address [0.0.0.0]? 50.10.1.6
Source address [0.0.0.0]? 128.180.22.13

Syntax: statistics

Originate default route:               No (0, 0.0.0.0)
RIP interfaces:                        1
Memory allocation failures:            0
I/O buffer allocation failures:        0
Responses sent to neighbors queries:   12
Changes made to the routing database:  10591

Traceroute [M]

A traceroute is complete when

• The destination is reached.

• An ICMP Destination Unreachable is received.

• The path length reaches 32 router hops.

This command is available at the RIP> prompt for convenience. For more information, enter this command at the IP> prompt. See Using IP.

Syntax: traceroute interface address

TRACEROUTE 128.185.124.110: 56 data bytes
 1 128.185.142.7 16 ms 0 ms 0 ms
 2 128.185.123.22 16 ms 0 ms 16 ms
 3 * * *
 4 * * *
 5 128.185.124.110 16 ms ! 0 ms ! 0 ms !