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Losing Packets with EIGRP and Some PCs are Unreachable

ashfar68737
Beginner
Beginner

Hello,

 

I'm implementing EIGRP on a network using Packet Tracer and when I try to ping some PCs, either some packets are lost or it replies with destination host unreachable. I've made sure gateways are correct. Looked through the routing tables and neighbor addresses, but I'm unable to identify the problem. There are some PCs that ping successfully to most PCs and others that don't ping at all, like PC 1. Routers ping successfully to each other and PCs to their routers as well. though.

I've tried to reconfigure EIGRP numerous times, but it's not working. I'm not sure if the gateways are the problem or the EIGRP configuration itself.

 

Many thanks in advance

 

1 Accepted Solution

Accepted Solutions

 

i see file, thanks, I think EIGRP auto-summary is the issue here;  you should disabled auto summary with command no auto-summary under EIGRP process for all routers.  You should not use auto-summary if you do subnetting. 

this is what I see  on SA-Riyadh to PC2 route is to Null, which means drop packets, AD is 5

SA-Riyadh#sh ip ro 197.155.1.135

Routing entry for 197.155.1.0/24

Known via "eigrp 1", distance 5, metric 28160, type internal

Redistributing via eigrp 1

Last update from 0.0.0.0 on Null0, 00:08:53 ago

Routing Descriptor Blocks:

* 0.0.0.0, from 0.0.0.0, 00:08:53 ago, via Null0

 

 

Regards, ML
**Please Rate All Helpful Responses **

View solution in original post

9 Replies 9

Martin L
VIP Advisor VIP Advisor
VIP Advisor


You can attach PT file here for us to see; file must be in a zip form, so zip it and attach.

 

Regards, ML
**Please Rate All Helpful Responses **

file zipped and attached

 

i see file, thanks, I think EIGRP auto-summary is the issue here;  you should disabled auto summary with command no auto-summary under EIGRP process for all routers.  You should not use auto-summary if you do subnetting. 

this is what I see  on SA-Riyadh to PC2 route is to Null, which means drop packets, AD is 5

SA-Riyadh#sh ip ro 197.155.1.135

Routing entry for 197.155.1.0/24

Known via "eigrp 1", distance 5, metric 28160, type internal

Redistributing via eigrp 1

Last update from 0.0.0.0 on Null0, 00:08:53 ago

Routing Descriptor Blocks:

* 0.0.0.0, from 0.0.0.0, 00:08:53 ago, via Null0

 

 

Regards, ML
**Please Rate All Helpful Responses **


In IOS 15, this EIGRP no auto-summary commands is there by default, so might be invisible. in other words, Cisco made it default EIGRP comes with summary disabled.
you are using IOS 12 .x routers; not sure if that on purpose or accidentally. CCNA exam is based on IOS 15 but , on the other hand, is good to know iOS 12.x for TS purpose.

I had no idea about the difference between IOS 12 and 15. Thank you. Perhaps that's why no auto-summary wasn't mentioned in the lab. We've been told that so far the type of router doesn't matter.


if no auto-summary wasn't mentioned in the lab, they must have assumed you will use IOS 15.

I did no auto-summary. That totally solved the problem! Thank you so so much!

 

Do you have an idea why would the 1st reply times out? The rest three replies do come through. It's only happening with PC1.

 

EDIT: Alright, I just saw the null remark. Now it works perfectly

Georg Pauwen
VIP Master VIP Master
VIP Master

Hello,

 

I think you have dual paths that cause packets to be load balanced. If you don't want that, you can increase the delay. I have increased the delay to 1000 on the serial 0/0/0 interfaces...

 

 

Thank you so much for editing the topology itself!
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