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Webcast-Catalyst9k
New Member

eigrp question

<p>Hi,</p>

<p>I have a question about eigrp routing:</p>

<p>the Vlan interfaces 12 ( Network 192.168.12.0/24)  and VLAN Interface 16 (Network 192.168.16.0/24 ) are configured on the same switch. If  I set the command "sh ip route" from a other switch in the network I see different  hops count ( to the network 192.168.16.0 only 2 hops  but the Network 192.168.12.0 a higher hop 7) .  Please Help.</p>

<p>msfc1#sh ip route 192.168.12.0<br />

Routing entry for 192.168.12.0/24<br />

  Known via "eigrp 1", distance 90, metric 4608, type internal<br />

  Redistributing via eigrp 123<br />

  Last update from 192.168.22.150 on Vlan4002, 00:35:48 ago<br />

  Routing Descriptor Blocks:<br />

    192.168.22.149, from 192.168.22.149, 00:35:48 ago, via Vlan4002<br />

      Route metric is 4608, traffic share count is 1<br />

      Total delay is 80 microseconds, minimum bandwidth is 1000000 Kbit<br />

      Reliability 255/255, minimum MTU 1500 bytes<br />

      Loading 1/255, Hops 7<br />

  * 192.168.22.150, from 192.168.22.150, 00:35:48 ago, via Vlan4002<br />

      Route metric is 4608, traffic share count is 1<br />

      Total delay is 80 microseconds, minimum bandwidth is 1000000 Kbit<br />

      Reliability 255/255, minimum MTU 1500 bytes<br />

      Loading 1/255, Hops 7</p>

<p>msfc1#sh ip route 192.168.16.0<br />

Routing entry for 192.168.16.0/24<br />

  Known via "eigrp 1", distance 90, metric 3328, type internal<br />

  Redistributing via eigrp 123<br />

  Last update from 192.168.22.137 on Vlan4001, 00:36:45 ago<br />

  Routing Descriptor Blocks:<br />

    192.168.22.138, from 192.168.22.138, 00:36:45 ago, via Vlan4001<br />

      Route metric is 3328, traffic share count is 1<br />

      Total delay is 30 microseconds, minimum bandwidth is 1000000 Kbit<br />

      Reliability 255/255, minimum MTU 1500 bytes<br />

      Loading 1/255, Hops 2<br />

  * 192.168.22.137, from 192.168.22.137, 00:36:45 ago, via Vlan4001<br />

      Route metric is 3328, traffic share count is 1<br />

      Total delay is 30 microseconds, minimum bandwidth is 1000000 Kbit<br />

      Reliability 255/255, minimum MTU 1500 bytes<br />

      Loading 1/255, Hops 2</p>

<p>Thanks,</p>

<p>Nouri</p>

5 REPLIES

Re: eigrp question

Not enough information but according to your output, 192.168.22.149 is where you learned that route.  How is 192.168.22.149 learning the route to 192.168.12.0. 

New Member

Re: eigrp question

Hi,

I paste a Network draft, maybe is simple to understanding.

Regards

Hall of Fame Super Silver

Re: eigrp question

Hello Noureddine,

your architecture is a ring topology.

From your outputs in first post:

one subnet is learned via vlan 4001 that is the shortest path to core L3 switch.

the other subnet is instead learned via Vlan 4002 and makes all the trip around the ring towards the core switch thorough all the other L3 switches.

For this reason its metric is higher and also its hop count: if you look at the picture 7 hops are required going via vlan 4002 to reach core switch.

To understand why this happens you need to examine EIGRP configuration of core router and of router (L3 switch) between the device in blue and the core switch.

Check to see if there are distribute-list applied inside the

router eigrp process

on core or on device with next hop in vlan 4001:

or core is not advertising the prefix to device with next hop in vlan 4001 or it is the second device to have a filter.

Another possibility is the usage of

offset-list again check the configuration of eigrp processes on

core and device with next-hop in vlan 4001.

if you like you can post the configuration of eigrp processes on the three devices.

Hope to help

Giuseppe

New Member

Re: eigrp question

Hi,

thank you for your help. I think I found the mistake

the Core switch don't annouce the network 192.168.12.0 as direct connected.

A nother switch core2 annouce the network 192.168.12.0 an direct connected

msfccore1#sh ip eigrp topology 192.168.12.0

IP-EIGRP topology entry for 192.168.12.0/24

State is Passive, Query origin flag is 1, 0 Successor(s), FD is 4294967295

Routing Descriptor Blocks:

msfccore2#sh ip eigrp topology 192.168.12.0

IP-EIGRP topology entry for 192.168.12.0/24

State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2816

Routing Descriptor Blocks:

0.0.0.0 (Vlan12), from Connected, Send flag is 0x0

Composite metric is (2816/0), Route is Internal

Vector metric:

Minimum bandwidth is 1000000 Kbit

Total delay is 10 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 0

Hall of Fame Super Silver

Re: eigrp question

Hello Noureddine,

yes there was a missing network command under router eigrp in mdfccore1.

Good news you have solved your issue

Best Regards

Giuseppe

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