Download - Extreme RIP

© 2008 Extreme Networks, Inc. All rights reserved. ExtremeXOS Operation and Configuration, Version 12.1. Part number DOC-00919.

Configuring RIP

ExtremeXOS™ Operation and Configuration, Version 12.1

Slide 2

Student Objectives

Upon completion of this module, you will be able to:

Describe the RIP routing protocol.

Identify the limitations of RIP version 1.

List the benefits of RIP version 2.

Interpret RIP routing table entries.

Describe the Split Horizon and Poison Reverse loop resolution protocols.

Describe the operation of triggered updates.

Configure the RIP routing protocol.

Verify the RIP configuration.

Test RIP operation.

Note: Depending on the needs of the students, the instructor may choose to reduce or eliminate the protocol overview portion of this module.

Slide 3

Limitations of Manual Configuration

What if you have 50 switches, 10 subnetworks, a meshed topology, and 500 devices, what now?

Slide 4

Routing Information Protocol

A distance-vector protocol used as an Interior Gateway Protocol.

First used in the Advanced Research Projects Agency Network (ARPAnet) as early as 1969.

It is primarily intended for use in homogeneous networks of moderate size (20-30 switches or less).

Relatively simple to understand and implement.

Each router creates its routing table based on route information exchanged between neighbors.

Supported by all Extreme Networks switches.

Distance-Vector

Distance - Hop Count

Vector - Next Hop Router

RIP Network

?

Slide 5

Routing Information Protocol (Continued…)

The router exchanges update messages with each neighbor every 30 seconds.

Stale routes are removed from the routing table.

There are two versions of RIP.

In RIP V1, 25 routes can be advertised in a single packet. This limits the maximum packet size to 512 octets.

Supports 2 types of loop resolution protocols.

• Split Horizon, Poison Reverse

Supports triggered updates.

RIP Network

Updates Every 30 Seconds

?

Slide 6

Limitations of RIP Version 1

Only understands class A, B, and C IP addresses.

Does not propagate subnetwork mask information in its updates.

Cannot support variable length subnetwork masks.

Uses broadcasts for update delivery.

It is an insecure routing protocol.

Updates:• Sent as broadcast• Networks only (no subnetwork

masks)

RIP Network

?

Slide 7

RIP Version 2

Fixes many of the limitations of RIP-1.

Is a classless routing protocol.

Supports variable length subnetwork masking.

Supports Classless Internet Domain Routing (CIDR).

Has features to make it backward compatible with RIP Version 1.

Supports authentication (not supported on Extreme Switches).

• Clear text password

• MD5 – checksum (RFC 2082)

Uses multicast for update delivery.

RIPv2 network

Network 129.128.128.0

Subnet 255.255.192.0

Network 129.128.128.0

Subnet 255.255.192.0Network 129.128.0.0

RIPv1 network

RIPv2 network

Slide 8

Routing Table and Route Advertisement

Contains an entry for every known destination network.

Contains the following information:

• Origin of the route.

• IP Address of destination network.

• IP address of the next router (gateway).

• Metric (hop count) to the destination network.

• Duration of time since the last entry update.

Route Advertisement of VLANs

• Only those VLANs configured with an IP address, configured to forward IP, and running RIP have their subnetworks advertised.

Ori Destination Gateway Mtr Flags VLAN Duration *r 10.10.11.0/24 10.10.99.121 2 UG-----um-- bbone 0d:0h:18m:36s *r 10.10.20.0/24 10.10.99.122 3 UG-----um-- bbone 0d:0h:09m:06s *r 10.10.33.0/24 10.10.99.124 2 UG-----um-- bbone 0d:0h:18m:53s *d 10.10.55.0/24 10.10.55.126 1 U------u--- white 0d:3h:21m:52s d 10.10.60.0/24 10.10.60.126 1 -------u--- brown 0d:3h:21m:00s *d 10.10.99.0/24 10.10.99.126 1 U------u--- bbone 0d:3h:21m:35s *d 127.0.0.1/8 127.0.0.1 0 U-H----um-- white 0d:3h:34m:16s

Route Table

Slide 9

Routing Loops

Router A advertises the route to the target network to Router B.

Router B advertises the route to the target network learned from A to C.

Router C advertises the route back to router B over the port that supplied the route.

Router B believes it has two routes to the target network when actually only one exists.

When the valid route becomes unavailable the router tries to use the alternate route.

Traffic is sent over the original route and looped back again.

Target Network

A

C

B

Problem!!

Target Network

Using A M=1

Target Network

Using B M= 2

Target Network

Using C M=3

B Routing Table

Target network using A M=1

Target network using C M=3

C Routing Table

Target network using B M=2

Slide 10

Counting to Infinity Problem

Complex networks can contain multiple routing loops.

Routers re-advertise routes out interfaces from which they were learned.

When the valid route becomes unavailable routers advertise routes with ever increasing hop count metrics.

Old route entries will be replaced by new route entries.

Behavior repeats until the max hop count reaches infinity (16 - unreachable).

Causes slow convergence.

Target Network

C

B

C Routing Table


B Routing Table


Target Network using C M=16

A

Slide 11

Split Horizon

Used to prevent routing loop.

Enabled by default on the switch.

Router does not advertise a route back out the port that the route was originally learned on.

The possibility of a loop has been eliminated using split horizon.

Split Horizon prevents route from being sent!!

Target Network

Target Network

Using C M=3

A

C

B

Target Network

Using A M=0

Target Network

Using B M= 1

C Routing Table


B Routing Table


Slide 12

Poison Reverse

Routers advertise routes with hop count of 16 (unreachable).

Faster convergence.

Poison Reverse takes precedence over split horizon when both are enabled to prevent loops.

Enabled by default.

Possible increased size of routing messages.

Target Network

Target Network

Using C M=16

A

C

BTarget Network using C M=16Target Network using A M=1

B Routing Table

Target Network using B M=2C Routing Table

Target Network

Using A M=0

Target Network

Using B M= 1Poison Reverse causes Router C to advertises route as unreachable.

Slide 13

Triggered Updates

Sent out whenever the metric for a route changes and the router is required to send an update immediately.

• Even if it is not yet time for a regular update message to be sent.

Generally result in faster convergence.

Results in more RIP-related traffic.

Target Network

BA Target = 0

Target = 1

Target = 2

Target = 4Target = 4

Target = 6



Target = 3



failed route

Slide 14

RIP Limitations

Limit of 15 hops between the source and the destination networks.

Bandwidth taken up by periodic broadcasts of entire routing table.

Slow convergence.

Routing decisions based on hop count.

Flat networks; no concept of areas or boundaries.

RIP Network

Slide 15

RIP Configuration Steps

Create and configure VLANs.

1. Configure the VLAN with an IP address.

2. Enable IP Forwarding.

3. Enable RIP on VLANs that do RIP routing.

4. Enable RIP globally on the switch.

5. Verify RIP configuration.

Slide 16

General IP Configuration Commands

Create and configure VLANs:

• create vlan <vlan name>

• configure vlan <vlan name> add ports <portlist>

Configure VLAN with an IP address:

• configure vlan <vlan name> ipaddress <ipaddr> {<netmask> | <mask length>}

Enable IP forwarding:

• enable ipforwarding

Slide 17

RIP Specific Configuration Commands

Enable RIP on VLANs that do RIP routing:

• configure rip add vlan [<vlan name> | all]

Enable RIP globally on the switch:

• enable rip

Disable RIP on VLANs:

• configure rip delete vlan [<vlan name> | all]

Disable RIP globally on the switch:

• disable rip

When RIP is disabled on the interface, the parameters are not reset to their defaults.

Slide 18

RIP Configuration Example

Configuration for R1:

create vlan vlan1ripconfigure vlan1rip add ports 1configure vlan1rip ipaddress 10.1.0.1/24

create vlan vlan0ripconfigure vlan0rip add ports 2,3configure vlan0rip ipaddress 10.0.0.1/24

enable ipforwardingconfigure rip add vlan vlan0rip configure rip add vlan vlan1rip enable rip

Similar configurations for R2 and R3

.1

10.0.0.0 / 24VLAN0rip

.2

.1

.3

.2

10.2.0.0 / 24VLAN2rip

.3

10.3.0.0 / 24VLAN3rip

R2 R3

R1

10.1.0.0 / 24

VLAN1rip

RIP Network

Slide 19

RIP Timer and Cost Configuration Commands

Configure RIP update timer:

• configure rip updatetime {<seconds>}

Configure RIP route timeout:

• configure rip routetimeout {<seconds>}

Configure RIP garbage time:

• configure rip garbagetime {<seconds>}

Configure RIP VLAN cost:

• configure rip vlan [<vlan name> | all] cost <cost>

Slide 20

Additional RIP Configuration Commands

Configure RIP receive version:

• configure rip rxmode vlan [vlan name | all][none | v1only | v2only | any]

Configure RIP transmit version:

• configure rip txmode vlan [vlan name | all] [none | v1only | v2only | any]

Enable or disable specific RIP features:

• [enable | disable] rip [aggregation | export | |originate-default | poisonreverse | splithorizon | triggerupdates | use-ip-router-alert]

Unconfigure RIP:

• unconfigure rip {vlan <vlan name>}

Slide 21

Verifying RIP Configuration

Timers

RIP, Split Horizon, Triggered Updates, Poison Reverse Status

Slide 22

Verifying RIP Interfaces and Routes

Slide 23

Verifying IP Forwarding and VLAN Interface

VLAN name and IP address

Slide 24

Verifying the Route Source

Preferred route flag

Origin of route is RIP

Slide 25

Summary

You should now be able to:

Describe the RIP routing protocol.

Identify the limitations of RIP version 1.

List the benefits of RIP version 2.

Interpret RIP routing table entries.

Describe the Split Horizon and Poison Reverse loop resolution protocols.

Describe the operation of triggered updates.

Configure the RIP routing protocol.

Verify the RIP configuration.

Test RIP operation.

Slide 26

Lab

Turn to the Routing Information Protocol (RIP) Lab in the ExtremeXOS™ Operations and Configuration - Lab Guide Rev. 12.1

and complete the hands-on portion of this module.


Review Questions


This presentation contains forward-looking statements that involve risks and uncertainties, including statements regarding our expectations as to products, trends and our performance. There can be no assurances that any forward-looking statements will be achieved, and actual results could differ materially from forecasts and estimates. For factors that may affect our business and financial results please refer to our filings with the Securities and Exchange Commission, including, without limitation, under the captions: “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” and “Risk Factors,” which is on file with the Securities and Exchange Commission (http://www.sec.gov). We undertake no obligation to update the forward-looking information in this release.


The End

© 2008 Extreme Networks, Inc. All rights reserved. ExtremeXOS Operation and Configuration, Version 12.1. Part number DOC-00919.© 2008 Extreme Networks, Inc. All rights reserved. ExtremeXOS Operation and Configuration, Version 12.1. Part number DOC-00919.