Routing Chapter Five Notes--- Rip

7/31/2019 Routing Chapter Five Notes--- Rip

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CHAPTER 5 NOTES RIP

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RIP CHARACTERISTICS

RIP is a distance vector protocol RIP uses hop count as its only metric for path selection Advertised routes with hops greater than 15 are unreachable Messages are broadcast every 30 seconds

NOTE: The data portion of a RIP message is encapsulated into a UDP segment with both the source port

and destination port set to 520. The IP header and data link header add broadcast destination addresses

before the message is sent out to all RIP configured interfaces.

RIPv1 HEADER

COMMAND: 1 for a request, 2 for a reply VERSION: 1 for RIPv1, 2 for RIPv2 MUST BE ZERO: This field is for future expansion of RIP

RIPv1 MESSAGE FORMAT

ADDRESS FAMILY IDENTIFIER: 2 for IP unless a Request for the full routing table in whichcase, set to 0

IP ADDRESS: The address of the destination route, which may be a network, a subnet, or a hostaddress

METRIC: Hop count between 1 and 16. Sending router increases metric before sending out themessage

NOTE: One RIP update can contain up to 25 route entries. The maximum datagram size is 504 bytes, not

including the IP or UDP headers.

NOTE: RIPv1 is a Classful routing protocol. It does not send subnet mask info.

Classful Routing

8 BITS 8 BITS 8 BITS 8 BITS

CLASS A Network Host Host Host CLASS A 1.0.0.0 THRU 126.255.255.255

255 . 0 . 0 . 0

CLASS B Network Network Host Host CLASS B 128.0.0.0 THRU 191.255.255.255

255 . 255 . 0 . 0

CLASS C Network Network Network Host CLASS C 192.0.0.0 THRU 223.255.255.255


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NOTE: Administrative Distance (AD) is the trustworthiness (or preference of a route). RIP has a

DEFULTAD of120. It is least preferred in IGP.

ENABLING RIP SYNTAX

Steps to enabling RIP {CHAPTER FIVE 5.2.2.1 and 5.2.3.1}o R1# config to R1(config)#router ? { this will list the routing protocols the IOS supports}o R1(config)# router ripo R1 (config-router)#network directly-connected-classful-address

NOTE: under the network command, enter classful address for each directly connected

network.

To Negate Ripo no router rip

THE NETWORK COMMAND

Puropse:

Enables the sending and receiving of RIP updates for interfaces that belong to thespecified network.

Advertises the specified network in RIP updatesSyntax:

Router (config-router)#network directly-connected-classful-addressVERIFYING RIP: show ip route

Powerful Troubleshooting Tools:

NOTE: Before you configure any routing, static or dynamic, use show ip interface briefto make

sure all necessary interfaces are up and up.

Troubleshoot in this order:

Command show ip route verifies that routes received by RIP neighbors are installed inthe routing table. Note: an R code indicates RIP

Command show ip protocols This output can be used to verify most RIP parameters toconfirm that :

RIP routing is configured


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The correct interfaces send and receive RIP updates The router advertise the correct networks RIP neighbors are sending updates

Note: This command also useful for verifying EIGRP and OSPF.

Command debug ip rip is used to find issues with RIP updates. Itdisplays RIP routingupdates as they are sent and received.Because updates are periodic, you need to Wait

for next round of updates to see any output.

NOTE: Most RIP configuration errors involve an incorrect network statement configuration, a

missing network statement configuration, or the configuration of discontiguous subnets in a

classful environment.

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Routing Chapter Five Notes--- Rip