CCENT in training: need RIP understanding please

Answered Question
Dec 7th, 2009

I am currently attending a local community college and studying

Cisco via a networking degree program. I am going to take the CCENT tomorrow and felt pretty confident until I just took our practice final and a practice CCENT test. I did pretty well but I only received 1 out of 3 for a lab sim that showed up on both. I got credit for repairing a problem but got 0 for configuring RIP properly?!

Two routers, each had two subnets.

enable

config term

router rip

version 2

network ***

network ***

(saved after updating all)

I thought that should take of it. I am unclear of where my problem was? I was able to ping across networks and across subnets, and did check to see that RIP was in config with networks.

My guesses are the following;

a) Should have used all show commands because Cisco recommends to verify this way

b) Should have not added serial link (between routers) network to RIP config

c) Should have done something additional due to the class B networks that were subnetted on a /24 off each router

Please help, I am so unsure of what I am doing wrong.

Thanks,

Jason

I have this problem too.
0 votes
Correct Answer by Conor Cunningham about 7 years 1 month ago

Jason,

You are more than welcome, and, a big congratulations!

Good luck with ICND2 - if anything, I thought ICND1 was a little harder than ICND2, but that's not to say you still don't have to put in a fair amount of work to pass first time. ICND2 is a bit more fun, too.

I'm studying for my CCNA Security at the moment and BSCI for my CCNP - it's never ending!

Again, best of luck and if you have any questions, don't be afraid to ask!

Cheers,

Conor

Correct Answer by Conor Cunningham about 7 years 1 month ago

I think you're problem was to do with auto summary.

Since you had 4 172.16.0.0/16 networks, 2 on each router and separed by a discontiguous network (10.0.0.0) you must do 'no auto-summary' in the router rip config.

i.e.

router rip

version 2

no auto-summary

Without no auto-summary, rip will summarise all 172.16.0.0.

That means that on router 1 it will have a route like 172.16.0.0/16 via fastethernet x

If you use no auto-summary you would see (for example on R1)

172.16.1.0/24 via fa1

172.16.2.0/24 via fa2

172.16.3.0/24 via serial x

172.16.4.0/24 via serial x

Also, don't forget that when enabling a rip network, remember to keep the networks classful, i.e, class A, class B, class C, e.g.

router rip

network 10.0.0.0 (not 10.1.1.0 - class A) or network 172.16.0.0 (not 172.16.3.0 - class B)

This doesn't impact a real router as the IOS will fix it for you, but it will be considered an error on the exam, or so I am led to believe.

Does this help?

Cheers,

Conor

Correct Answer by Conor Cunningham about 7 years 1 month ago

Jason,

First of all could you see that a neighbour relationship had formed?

If not, check that the interface which you were advertising from wasn't in passive mode.

If you can provide us more detail as to what the networks were and what connections were  between them, that would help alot.

Also, debug ip rip events and show ip rip database are very useful commands.

Cheers,

Conor

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Correct Answer
Conor Cunningham Mon, 12/07/2009 - 08:07

Jason,

First of all could you see that a neighbour relationship had formed?

If not, check that the interface which you were advertising from wasn't in passive mode.

If you can provide us more detail as to what the networks were and what connections were  between them, that would help alot.

Also, debug ip rip events and show ip rip database are very useful commands.

Cheers,

Conor

jarowland Mon, 12/07/2009 - 08:36

They were 172.16.1.0/24 and 172.16.2.0/24 on R1

172.16.3.0/24 and 172.16.4.0/24 on R2

R1 and R2 connected on a 10.0.0.0 (cant remember the subnet)

Each subnet had only one device and were using the fa ports (172.16. subnets)

The 10.0.0.0 were using the serial ports.

Hope that helps to clarify.

Correct Answer
Conor Cunningham Mon, 12/07/2009 - 08:52

I think you're problem was to do with auto summary.

Since you had 4 172.16.0.0/16 networks, 2 on each router and separed by a discontiguous network (10.0.0.0) you must do 'no auto-summary' in the router rip config.

i.e.

router rip

version 2

no auto-summary

Without no auto-summary, rip will summarise all 172.16.0.0.

That means that on router 1 it will have a route like 172.16.0.0/16 via fastethernet x

If you use no auto-summary you would see (for example on R1)

172.16.1.0/24 via fa1

172.16.2.0/24 via fa2

172.16.3.0/24 via serial x

172.16.4.0/24 via serial x

Also, don't forget that when enabling a rip network, remember to keep the networks classful, i.e, class A, class B, class C, e.g.

router rip

network 10.0.0.0 (not 10.1.1.0 - class A) or network 172.16.0.0 (not 172.16.3.0 - class B)

This doesn't impact a real router as the IOS will fix it for you, but it will be considered an error on the exam, or so I am led to believe.

Does this help?

Cheers,

Conor

jarowland Mon, 12/07/2009 - 09:09

Ok, I had to pull out the ICND2 book. I am going to study the autosummarization portion and then set up a packet tracer sim to get a better understanding and feel for this new concept. I recall the sim question did point out and state something like "be sure to make any adjustments for subnet issues".

I just find it odd that the ICND1 book makes only a small mention of it yet it is included on the CCENT? Well, I guess the more knowledge the better prepared I will be.

Thanks for your help it is greatly appreciated,

Jason

jarowland Tue, 12/08/2009 - 07:52

Connor,

Thank you for pointing me in the right direction! I can't thank you enough. I was able to pass my CCENT this morning, first try, but I couldn't have done it without you helping me further my RIPv2 knowledge!

Again many thanks!

Jason

Correct Answer
Conor Cunningham Tue, 12/08/2009 - 08:01

Jason,

You are more than welcome, and, a big congratulations!

Good luck with ICND2 - if anything, I thought ICND1 was a little harder than ICND2, but that's not to say you still don't have to put in a fair amount of work to pass first time. ICND2 is a bit more fun, too.

I'm studying for my CCNA Security at the moment and BSCI for my CCNP - it's never ending!

Again, best of luck and if you have any questions, don't be afraid to ask!

Cheers,

Conor

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