Enabling RIP clarification... CCENT

anthonyg2879

Configuring RIP

When configuring the networks on RIP do i input the networks in their classful version only....? i know RIPv1 is classless and RIP v2 is classful but do u always input the network in its classful state with RIP...

not sure if auto-summary is something that we really need to know about with this certification .. ICND1

ex:

if i have a router going to another router or an ISP with a network address of 68.110.171.98/27

how would i configure RIP on that router:

network: 68.0.0.0 -> the classful way ... being that it is a class A

or find the network address from subnet /27

network: 68.110.171.96

Which one would be the correct way?

In the real world .. the router would prob take both ways but i am looking for the correct way to add in for the test so they dont deduct points...

if i have auto-summary enabled ... then it will auto-config the classless network into a classful one when i type in show run-config... correct?

and if i place "no auto-summary" it wont change to a classful address ... am i understanding this correctly....

AD227529

I think you've got it backwards. Everything I've studied about them says RIPv1 is classful and RIPv2 is classless. RIPv1 does not support VLSM, but RIPv2 does. You configure them on the classful boundary, regardless of version. For example, you would configure 68.110.171.98 as network 68.0.0.0 since it's a Class A network and the network portion is the first octet. You are correct in that in the real world you can configure it the classless way and the router should auto-correct it, but I think on the Cisco exam you have to configure it on the classful boundary in order for it to count. I'm taking the CCENT exam Wednesday and I've always entered RIP configurations on the classful boundary on the sims and it always worked. Good luck with your exams!

surfthegecko

everything I have read so far tells me its just a case of 'network 68.0.0.0'

No more too it as far as I can tell for the ICND1 course (CCENT Qualification).

Also I confirm with AD as I understand it:
Classless routing protocols are: RIPv2, EIGRP, OSPF & IS-IS
Classful routing protocols are: RIPv1 & IGRP

Neeko

The RIP network command is classful no matter which version of the protocol you are using. So in your example you would always enter 'network 68.0.0.0'.

I think you may need to clear up what the command actually does, which is two things. All interfaces that are part of the classful boundary of the specified network will be enabled for RIP updates. So if you have two interfaces on /26 networks e.g 192.168.10.65 and 192.168.10.129, when you enter 'network 192.168.10.0' you will enable both of these interfaces to send and receive RIP updates. Similarly, the command determines which networks configured on the router will be added to the RIP updates, which of course will just be the networks that each interface is part of.

Just because the network command is classful doesn't mean the local routing table will not contain any subnetted information, using the show ip route command will verify that so check it out.

Auto-summarization does not impact what is configured with the network command. Well, it does but no in the way you are thinking. Auto-summarizing is determined by each interface that is sending RIP updates, on a per entry basis. The network command will specify what interfaces will send and receive updates, and which local networks will be advertised, not whether routes will be summarized. Once you have all your selected interfaces enabled for RIP and the networks they are on ready to send as updates, each interface then checks the networks against certain parameters and decides whether they should be summarized or not.

For details on this, read this Cisco page: http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a0080093fd8.shtml#nd