Configuring RIP Directory
Allow the mono-broadcasting updtaed and grouped by RIP Router
Use the Offsets on the Route metric
Appoint
the RIP Version Number
Prohibit the Authentication of Source IP Address
Activate or Prohibit the Horizontal Split
Monitoring and Maintainance of RIP
Example of the RIP Configuration
The chapter illustrates how to
configure the RIP. If you would like to have the detailed description on the RIP
commands in this section, you can refer to the Chapter of "RIP
Commands" in the "Reference for the Network Protocol Commands".
If you would like to search the document with other commands, you can use the
master index for commands and conduct inline search.
The Route Information Protocol
(RIP) is a relatively old but still commonly used Interior Gateway Protocol
(IGP), which is mainly used in the small-sized network of the same kind.. And
RIP is a traditional Distance Vector Routing Protocol, which occurs in the RFC
1058.
RIP exchanges Routing Information through broadcasting UDP Packets. In the Router, the update Route Information will be sent every 30 seconds. In case that no update information from the neighbor router has been received within 180 seconds, the Routes from that neighboring router in the Routing Table will then be labeled as "Unusable". And if there is still no updated information received in the next 120 seconds, these Routes will be deleted from the Routing Table.
The Hop Count is taken by the RIP as a metric to measure
different routes. And the Hop Count refers to the number of the passed routers
of packets from the Source to the destination. The metric of the Route that is
directly connected to the Network is "0", the metric of the Route
whose network is not able to reach is "16". As the Route metric used
by the RIP is in a relatively small range, it is not applicable to large-scale
network. .
If a router has a default route,
RIP then will advertises the route to the false Network of 0.0.0.0. In fact, the
0.0.0.0 network does not exist, which is only used for realizing the function of
default route in RIP.. If the RIP has learned a default route, or the default
gateway is configured in router and configured with default metric, the router
will then announce the default network.
The RIP will send the updates to
the interface of the appointed network. If the network of the very interface is
not appointed, the network then will not be announced in any RIP updating. .
The RIP-2 of our company's router supports Plaintext and MD5 Authentication, Route Summary, CIDR and VLSM.
If you would like to configure
the RIP, the following tasks are necessary. While you have to first activate the
RIP, the other tasks are optional.
Start the RIP
Enable Unicasting of RIP route update messages.
Apply the offset on the route metric
Regulate the Timer
Designate the RIP Version Number
Activate the RIP Authentication
Prohibit Route summary
Prohibit the Authentication on Source IP Address
Activate or Prohibit the split-horizon
Example of the RIP Configuration
Example of the split-horizon
To activate
the RIP, the following steps shall be carried out under the global configuration
mode:
Step |
Command |
Purpose |
1 |
router rip |
Activate the RIP Routing Process and enter the router configuration mode. |
2 |
network network-number <network-mask> |
Appoint the Network Number relevant to the RIP Routing Process |
Allow
the mono-broadcasting updtaed and grouped by RIP Router
The RIP is a broadcasting-Type Protocol. If you would like the updating of routes to to access to the non-broadcasting type network, the router shall be configured so as to enable information exchange. To this end , the following commands shall be used under router configuration mode:
Command |
Purpose |
neighbor ip-address |
Define a neighbor router to exchange with it the Routing Information. |
In addition, if you would like to control which interface(s) that can be used to exchange routing information, the command "ip rip passive" can be used to designate an interface or some interfaces prohibiting the sending of the update of routes. If necessary, please refer to the relevant discussion on the route filtration in the "Filtrating the Routing Information" in the Chapter of " Protocol-Independent Commands in Configuring IP Router”.
Use the Offsets on the Route metric
Offset List is taken to increase an
offset on the Input and Output Routes, which have been learned with the RIP. On
the other hand, you can use the Access List or the interface to limit the Offset
List. In order to increase the Route metric, the following commands should be
executed in the router configuration mode:
Command |
Purpose |
offset-list {[interface-type number]|* }{in|out} access-list-name offset |
Increase an offset on the route metric |
Routing protocols use several timers to determine the frequency for sending the updating of routes, how long the router will become invalid and other parameters. You can regulate these timers so as to make the performance of the Routing Protocols more suitable to the requirements of the network.
It is also possible to regulate the Route Protocol to accelerate the Convergence Time of all kinds of the IP Routing computation, to quickly backup to the redundant router so as to minimize the time of quick recovery. To regulate the Timer, the following commands should be used under router configuration model.
Command |
Purpose |
timers holddown value |
Regulating the time (Unit: Second) it take to delete certain route from the Routing Table |
timers expire value |
Regulating the time (Unit: Second) that the router is announced to be invalid. |
timers update value |
Regulating the frequency for sending the updating of the Router (the time interval between sedning of the updating of routing, (unit: Second) |
Appoint the RIP
Version Number
The RIP-2 of our company's router supports Authentication, Password Management, Route summary, CIDR and VLSM.
Under the default circumstance, the router can receive the updates of RIPv1 and RIPv2, while it can only send the updates of RIP-1. By configuration, the router can be set to receive and send the updates of RIPv1 only, or receive and send the updates of RIPv2 only. For this purpose, the following commands should be taken in the router configuration mode:
C |
Purpose |
version {1 | 2} |
Configure the router to send and receive the updates of RIPv1 or RIPv2 only. |
The above tasks are controlling the default behavior of the RIP. And you can also configure a certain interface to change this default behavior. In order to control the interface to send the RIP-1 updates or the RIP-2 updates, the following commands shall be used under interface configuration mode
Command |
Purpose |
ip rip send version 1 |
Configure the interface to send the updates of RIP-1 only. |
ip rip send version 2 |
Configure the interface to send the updates of RIP-2 only. |
ip rip send version compatibility |
Send by broadcasting t the Updating of RIP-2 message. |
At the
same time, to control the interface to receive the updates of RIP-1 and RIP-2,
the following commands shall be used under the interface configuration mode:
Command |
Purpose |
ip rip receive version 1 |
Configure the interface to receive the updates of RIP-1 only. |
ip rip receive version 2 |
Configure the interface to receive the updates of RIP-2 only. |
ip rip receive version 1 2 |
Configure the interface to receive the updates of RIP-1 and RIP-2 only. |
RIP-1 does not support
Authentication. If you would like to send and receive the updates of RIP-2, you
can activate the function of RIP Authentication on the interface.
On the activated interface of RIP, we support 2 kinds of Authentication Modes: Plaintext Authentication and MD5 Authentication. the Plaintext authentication is used in each subgroups of BIP-2 under default status.
Note:
Regarding the safety, please don’t use Plaintext Authentication in the groups
of RIP, because the unencrypted authentication key would be sent to each update
of the RIP-2. If the safety is not a big question, (in case that it is
guaranteed that the wrongly configured host can not take part in the route) the
Plaintext Authentication can be used.
To configure the RIP Plaintext
Authentication, the following steps should be taken under interface
configuration mode:
Step |
Command |
Purpose |
1 |
ip rip authentication simple |
Activate the RIP Authentication |
2 |
ip rip password [string] |
Configure the Plaintext Authentication key for the interface |
In order to configure the MD5 Authentication, the steps below should be taken under interface configuration mode:
Step |
Command |
Purpose |
1 |
ip rip authentication message-digest |
Activate the RIP MD5 Authentication |
2 |
ip rip message-digest-key [key-ID] md5 [key] |
Configure the MD5 Authentication key for the interface |
Under the default circumstance,
the RIP-2 supports the automatic route summary, summarizing the RIP-2 Routes
when crossing the boundary of the classified network. And the RIP-1 Automatic
Route Gathering Function is always activated.
If there is a separated Sub-net,
it is necessary to prohibit the Route summary to declare this Sub-net. If the
Route Gathering is prohibited, when crossing the boundary of the classified
network, the router will then send the route information of the sub-net and the
host. Under the router configuration mode, the following command should be taken
to prohibit the automatic gathering.
Command |
Purpose |
no auto-summary |
Prohibit the Automatic summary |
Prohibit the Authentication of Source IP Address
Under the default circumstance, the router will authenticate the Authenticable Source IP Address of the received route update. If this address is illegal, the router update will then be rejected.
If
you have a router in hope to receive the updating from it, but you have not
configured the corresponding "network" or "neighbor" on the
receiver, the function should be therefore prohibited. However in the common
practice, this command is not recommended to use. Under router configuration
mode, the following commands will prohibit the default function of
authenticating the source IP address in incoming route updates
Command |
Purpose |
no validate-update-source |
Prohibit to authenticate the Source IP Address of the incoming RIP Router Updating. |
Activate or Prohibit the Horizontal Split
Normally, the router, which is connected
with IP Network and using the Distance Vector Routing Protocol, takes
split-horizon to lower the possibility of route loops. The Split-Horizon
prevents the announcements of route
information to the receiving interface of this route information. In this way,
communication within several routers (especially when the loop breaks) will be
optimized. However, to Non-broadcasting Network (such as FR), things are not so
easy. And maybe you have to prohibit the Horizontal Split.
If an interface has been configured with a supplementary IP Address and he Horizontal Split has been activated, the update-Source IP Address of the route update may not include every secondary IP address. The Source IP Address of one Route Update can only include one Network Number (unless the split-horizon is Prohibited).
In order to activate or prohibit
the Horizontal Split, the following commands should be taken under interface
configuration mode:
Command |
Purpose |
ip rip split-horizon |
Activate the Split- Horizon |
no ip rip split-horizon |
Prohibit the Split- Horizon |
Under the default circumstance, for the
point to Point Interface, the Split-Horizon is activated; For Point-to multiple
point Interface, the Split-Horizon is prohibited.
Please refer to the specific example of using Split-Horizon in the "Examples of Split-Horizon" in Section of this Chapter.
Notice: Commonly, it is suggested that the default state remain unchanged unless you are sure that your application can't declare the route correctly until you change its state. Always remember: if the Split-Horizon is prohibited on a serial interface (and the interface is connected with a Packet-switched Network), you have to prohibit Split-Horizon to all routers in any relevant Multicast Group on that Network.
Monitoring and Maintainance of RIP
With the RIP monitored and maintained,
the Network Statistics can be displayed, such as: RIP protocol Parameter
Configuration, Network utilization, Real-time Tracing of Network Communication
and so on. Such information can help you judge the use of Network Resource and
further solve the network problems and know the reachability of network nodes .
the
following commands can be used to display the statistics information of all
kinds of routes under management statistics:
Command |
Purpose |
Show ip rip |
Display the present Status of RIP |
Show ip rip database |
Display all routes of RIP |
Show ip rip protocol | Display all the relevant information of RIP Protocol |
Under the management mode, the following commands shall be used to trace route protocol information.
Command |
Purpose |
debug ip rip database |
Trace the procedure information of RIP Routing such as Insertion into the Routing Table, Deletion from the Routing Table, Changes of Routes and so on. |
debug ip rip protocol |
Trace the RIP protocol messages. |
Example of the RIP
Configuration
Examples of the RIP Configuration is included in this section:
Basic Configuration of RIP
routerA
interface ethernet 1/1
ip address 192.168.20.81 255.255.255.0
!
interface loopback 0
ip address 10.1.1.1 255.0.0.0
!
router rip
network 192.168.20.0
network 10.0.0.0
!
routerB
interface ethernet 1/1
ip address 192.168.20.82 255.255.255.0
interface loopback 0
ip address 20.1.1.1 255.0.0.0
!
router rip
network 192.168.20.0
network 20.0.0.0
!