Cannot Ping RIP Routed IP

Answered Question
Nov 21st, 2007
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Hi All,


I have 3 routers within Boson Sim. PIR1, PIR2 and PIR3. Serial 0/0 on PIR1 has an IP 195.10.1.2/30 and PIR2 serial 0/0 195.10.1.3/30. PIR2 also has an IP 195.10.1.5/25 on the fastethernet 0/0 and PIR3 has an IP 195.10.1.6/25. All have been configured for RIP ver2. I added network 195.10.1.0 on all 3. The only connection that won't ping is between PIR1 and PIR2. What have I missed? Cheers.


coolboarderguy

Correct Answer by nikhil.engineer about 9 years 5 months ago

Th ip add scheme you were using were overlapping each other.If your using /25 then the range is from 195.10.1.0-195.10.1.127. So, the other serial wont take the same interface.

Plan your ip add acheme in follg way:-

PIR1-195.10.1.129/30

PIR2-195.10.1.130/30

PIR2-195.10.1.1/25

PIR3-195.10.1.2/25


HTH.


Cheers,

Nikhil E.

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Edison Ortiz Wed, 11/21/2007 - 18:02
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195.10.1.3/30 is the broadcast address for subnet 195.10.1.0/30.


The allowed host addresses for that subnet are 195.10.1.1/30 and 195.10.1.2/30

coolboarderguy Wed, 11/21/2007 - 18:11
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DOH!! Ok, when setting serial 0/0 on PIR2 to 195.10.1.2/30 it says it overlaps with fastethernet 0/0 195.10.1.0. Cheers.


coolboarderguy

coolboarderguy Wed, 11/21/2007 - 19:20
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Hi All,


obviously I'm doing something fundamentally wrong here? Cheers.



Gateway of last resort is not set


195.10.1.0/25 is subnetted, 1 subnets

C 195.10.1.0 is directly connected, FastEthernet0/0


coolboarerguy

Richard Burts Wed, 11/21/2007 - 19:48
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Yes something is fundamentally wrong here. A basic concept of IP addressing and subnetting is that the same subnet should not exist in more than 1 place in the network. But you have taken the same /24 (class C) network and created serial link (/30) subnets and LAN (/25) subnets.

"PIR2 also has an IP 195.10.1.5/25 on the fastethernet 0/0 and PIR3 has an IP 195.10.1.6/25"

This puts the same /25 subnet on 2 different routers and the LAN subnet is using the same address space as the serial links.


My suggestion is to start over and plan a more effective addressing scheme.


HTH


Rick

Correct Answer
nikhil.engineer Wed, 11/21/2007 - 20:19
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Th ip add scheme you were using were overlapping each other.If your using /25 then the range is from 195.10.1.0-195.10.1.127. So, the other serial wont take the same interface.

Plan your ip add acheme in follg way:-

PIR1-195.10.1.129/30

PIR2-195.10.1.130/30

PIR2-195.10.1.1/25

PIR3-195.10.1.2/25


HTH.


Cheers,

Nikhil E.

coolboarderguy Wed, 11/21/2007 - 21:13
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Hi All,


ok, what's being said here, is, you can define larger subnet ranges and then break it down into smaller ones, IP/25 and then IP/30, but not IP/30 and then IP/25, yes? Cheers.


coolboardeguy

nikhil.engineer Wed, 11/21/2007 - 21:36
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Yes your absolutely right. Always go from high to low i.e. high no of users to low.This the best practice.

HTH.


Cheers,

Nikhil

Richard Burts Thu, 11/22/2007 - 09:58
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Nikhil


There is a serious problem in your suggestion. You suggest this:

PIR2-195.10.1.1/25

PIR3-195.10.1.2/25

but this means that the same subnet will exist in 2 different places. Both of those addresses describe a subnet which starts at 195.10.1.1 and goes through 195.10.1.127. It is a problem if you try to put the same subnet on 2 different routers. If you want at least 2 LAN subnets and some serial subnets to all come out of a /24 (class C) address space then the LAN subnets can not be larger than /26 (instead of /25). With /25 there are only 2 subnets in the address space. With /26 you can have 4 subnets.


HTH


Rick

nikhil.engineer Thu, 11/22/2007 - 10:15
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Rick,


I think u hv taken me in wrong way.I'll elaborate it for you.


PIR1-195.10.1.0/25-PIR2-195.10.1.128/30-PIR3


Cheers,

Nikhil E.

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